A:
which would be the command for inventory (uid) of tag, using mlx90121 and tag by texas?
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Q:
The Anticollision sequence is not controlled by the chip itself but inside the microcontroller and the Inventory command needs to be implemented according to the protocol used.
Texas provides transponders working with the standard ISO15693 and/or a dedicated protocol called TAG-IT (only the request from the transceiver changes, the modulation from the transponder is the same for both ISO15693 and TAG-IT).
For more information about the Inventory command, please refer to the documentation of these two protocols.
For easy development and understanding of the protocol, Melexis provides a development kit called DVK90121 which includes the complete software for ISO15693 and ISO14443 communication.
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Q:
it is not this, it would like to know the commands, bytes or simbols to send to transciever its very dificil...
I' dont making siency, work school or another similar thing. I am developing with commercial porposite to make and to produce in wide scale. I am thinking seriously about using to transciever of another manufacturer.
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A:
Sorry but to help you I need to have more details about your problem. The difficulties come from the Interface between the MLX90121 and the microcontroller or from the understanding of the ISO15693 standard?
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Q:
I'm currently working on a reader based from the MLX90121 transceiver and I'm new to designing antenna. Can you shed some light on how you come up with the design of the antenna of the evaluation board of the MLX90121. If possible can you provide me the circuit of the antenna that you used for the evaluation board so that I'll have a referenced circuit.
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A:
Please send your details for delivery of the reference circuit. The design will be sent
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A:
Thanks sharing to me the antenna design. I just like ask some questions regarding the design. Not all the values of components are given, does this mean that I have to assume values for the unknowns until I achieve the value of 50 ohms and Q factor of 14? Are capacitors for this antenna serve as coupling or what? I'm also wondering if the thickness of the antenna trace would have a significant effect in the antenna system? Please enlighten me on this matters.
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Q:
Only the components with values given are mounted on the antenna. This means: C1 with 5-50pF, C2,4,7,9 with 1nF, R9 with 1k8 ohms and L1 with a Shortcut.
All these components form the matching network and adapt the antenna on a resistive 50 ohms @ 13.56MHz with a quality factor Q of about 14. This adaptation can be re-adjusted (small shift due to the tolerance of all components) with the tuned capacitor CV1.
The thickness of the antenna trace will impact the losses resistor of the antenna and then the quality factor Q. In our 12x12 cm antenna, the losses resistor is about 140mohms, which is small value in comparison to the equivalent series resistor of few ohms used to adjust the quality factor to about 14 for ISO standard communication. Then, the thickness of the antenna trace will not have a significant effect with antennas with a small quality factor.
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Q:
I am using the DVK90121 with the Firmwareversion 2007/02/02. in this version the iso 14443-b functions do not work correctly. the card does not answer... with the old version REQB and WUPB works fine...
are there any updates available?
another question according to 14443B... How I have to parse some Higherlayer instructions to the OS on the Card?
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Q:
some Problems are solved.... the REQB failure was just a timing problem. I change one constant and it worked find.
But the other one is still present. regarding to the block transmission protocol or the iso 7816 i am not able to parse some higherlayer instructions.
i think it is an timing problem, too. because i found something about FWI and FWT:
The maximum value of TR0 is 256/fs for ATQB only and (256/fs)*2^FWI for all other frames. i did not found it in a ISO but this document combines many information from the ISO standards.
Here fs = fc/16 = 13.56MHz/16!
The card sends a FWI in ATRQ of 11! Means 302us*2^11. pretty much longer then the TR0 for ATRQ.
i played arround with some constants which sets the Timer to look whether the DOUT is stable... but there is always NoTagResp.
am I right here? is it timing problem?
The card is in the active state. ready to accept higher layer instructions, but i think the firmware interrupts polling earlier, before the card has the chance to answer.
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A:
The times TR0 and TR1 are defined in the documents ISO14443-2 and ISO14443-3 of the standard.
TR1 can be from 18.88us (minimum value defined in the ATTRIB command) to 236us.
TR0 can be from 0 (ISO14443-3 AMD1) up to 4949ms.
Therefore, the time TR0 can be quite big and the reader (PCD) has to wait for a reply until the end of this specified TR0. Fortunately, the ISO14443B includes a TR1 including a sub-carrier modulation for the synchronization.
It is possible that the current firmware doesn't wait for such a long time. Therefore, you will have to modify it to be compliant with the transponder that you are using.
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Q:
Thanks for the reply, i will try it this way!
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Q:
i have implemented a 16 bit timer for polling the DOUT pin of 90121...
now i can cover the maximum FWT (about 5sec).
But my card doesnt answer...
Do you have some hints, regarding the half duplex transmission protocol in ISO 14443 part 4 clause 7...
My Card answer with a protocol info part in ATQB with 0x3381B1:
means:
3rd Byte:
FWI = B = 11
ADC = 0 = Application is proprietary
FO = 1 = CID is supported
2nd Byte:
256 Byte Framesize
ISO compliant
1st Byte:
How i have to interpret the two "3".
Does the Card support two Bitrateoptions? with 212 and 424kBit/s...
Where is the subcarrier frequency defined in the firmware?
Hope for some hints...
Just an answer to a Deselecting Block (iso 14443 - 4 claus 8; an SBlock with a deselect) will be a step forward!
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A:
The first byte of the ATQB defines the data rate supported by the transponder. For that, please refer to the table 19, page 33 of the ISO14443-4. This transponder supports 106kbps (mandatory to initiate the communication), 212kbps and 424kbps, uplink (Reader to TAG) and downlink (TAG to Reader).
The sub-carrier frequency will not be defined in the firmware as it will be removed by the digital decoder of the MLX90121. Please note that the MLX90121 only supports data rates up to 106kbps.
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Q:
thanks again. it works fine!!!
the datarate was wrong.
"Please note that the MLX90121 only supports data rates up to 106kbps." was the important hint. i just changed this Parameter 2 in ATTRIB and the card answered...
Thank you for ypur replies and time.
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Q:
I need technical information in configuring MLX90121 for Direct Tx/Rx. My application requires communication between the RFID transceivers. Based on the datasheet, I understand that MLX90121 supports direct tx/rx. I purchased four dev kits and I modified the firmware to configure the MLX90121 for direct Tx/Rx.
From my spectrum analyzer, I could see that MLX90121 is able to TX at 13.56 MHz. However, the other MLX90121 unit is not receiving any signal at the DOUT pin. I would greatly appreciate if anyone could help me with relevant documents or registter settings for properly configuring MLX90121 for direct TX/RX setup.
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A:
The configuration of the MLX90121 will depend to the type of communication used (data-rate, sub-carrier, ...). For more information, please refer to the application note "Support of different modulation modes" in the cookbook of the MLX90121 on available on our web site.
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Q:
Is it possible to communicate between two MLX90121 bases RFID readers using Direct TX/RX?
I have configured the MLX90121 which acts as the transmitter as follows
AnalogConfig - 0x63
DigitalConfig - 0x04
To send binary 1, I set DIN at 423KHz and to send binary 0,I am setting DIN at 484Khz.
For the MLX90121 configured as a FSK receiver, I would like to shut down the transmission section alone while the receiver is still active. So that I could receive the binary signals. Is this possible with MLX90121?
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A:
The MLX90121 is not intended to be used for peer to peer communication. In normal operation mode, the analog chain cannot be supplied with the PA OFF and therefore, cannot be used to receive information from another reader.
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Q:
i am using mlx90121 for development ISO Standard reader for Melexis antenna 12cm.x12cm. how many range for read/write Mifare ISO14443A?
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A:
Mifare transponders comply with the standard ISO14443-A level 1, 2 and 3 (Initialization and anti-collision). These transponders can be inventoried using the DVK90121 up to 9cm (this distance will be reduced according to the number of TAGs in the field).
Read/Write operations with Mifare are encrypted (doesn't comply with ISO14443 level 4 : smart card protocol) and therefore cannot be covered by the DVK90121.
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Q:
I am writing to acquire information about MLX 90121.
We are using the DVK 90121 for ISO 15693 RFID and We want to receive another reader's signal.
According to Application Note "MLX 90121 : Support of different modulation modes", MLX 90121 can support baseband communication
We are testing MLX 90121 using Base band communication ( 3.1.1 configuration and 3.1.2 configuration) but can't receive proper singal
so we have some question.
1. Can MLX 90121 receive ISO 15693 Reader's Signal ?
2. If it is possible, Which value is saved in configuration register ?
3. How should we use ck signal ?
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A:
The MLX90121 is compliant with the standard ISO15693 using a sub-carrier of 423.75kHz. For the register's configuration, please refer to the datasheet of the MLX90121 page 22.
Moreover, by applying a specific register's configuration, the MLX90121 can also be used to receive a base-band modulation. Please note that the output signal on DOUT results in short pulses to each edge of modulation. Therefore, it will not be possible to decode the NRZ (none return to zero) modulation as you don't have any information on the modulation level.
About how using the CK signal, please refer to the application note "MLX90121: Communication with ISO standards" available on our WEB-site.
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Q:
Dear denis
I have seen data sheet of the MLX 90121 and "MLX90121: Communication with ISO standards"
but, we want to operate MLX 90121 as RFID Tag of ISO 15693
In this case, another reader sends signal using base band communication so MLX 90121 must be configured for base band communication.
but, We are testing MLX 90121 using Base band communication ( 3.1.1 configuration and 3.1.2 configuration of "MLX 90121 : Support of different modulation modes") but can't receive proper singal
Best regards
Gwon Ho Ryu
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A:
Dear,
The MLX90121 must be configured according to the base band communication with low data rate (less than 40kbit/s). The majority voting is not used and CK pin must be set to zero (The MVEn bit in set to '1' or '0').
As a result, short pulses will be seen on DOUT at every rising and falling edge. This can be used to decode the position of the modulate pulse sent by an RFID reader and then to decode the corresponding information.
Best regards
denis
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Q:
Page 11 of the datasheet shows pin 2 (GND) connected to CPU output to control MODU. Is this correct? or should pin 2 be connected to GND?
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A:
The pin 2 of the MLX90109 has to be connected to the ground and not to the microcontroller. The schematic page 11 is correct only if the microcontroller output stays to ground. We will update the datasheet soon.
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Q:
I have two questions:
1.Witch one of MLX90109 & MLX90121 I have chouse for about 15 – 20 cm reading distance and minimum current needed by reader working with 3.3 v battery?
I prefer to use external coil antenna 70 - 80mm diameter on both reader and transponder side.
2.
Why in web store in don’t see EVB90109 & EVB90121 , MLX90109, MLX90121?
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A:
1.The MLX90121 (13.56MHz transceiver) will be a good choice for your application. 15-20 cm of operating distance can be achieved with ISO15693 smart card transponders and a 12x12cm square transceiver's antenna.
2.At that time the webstore has been discontinued please see our distributor's websites, digikey and future electronics for availability or contact your neares sales representative.
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Q:
What do you mean "At that time, we only promote our development kits DVK90109 and DVK90121"?
Can I buy MLX90109, MLX90121 chips without DVK in case everything OK and I need to build 100 reader's?
One more question. Can I buy one of DVK that include evaluation board for example DVK90109 and only evaluation board for second frequency?
As I understand development kits are the same and evaluations boards only a difference.
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A:
As explained, we prefer when customers start working with the DVKs, even if it is possible to buy from us the EVBs and even samples.
From our experience, DVKs greatly speed up the development cylce at the customer place.
DVKs are not generic: If you buy a DVK90121 and an EVB90109, you will need anyway to change the software of the DVK to turn it into a DVK90109.
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Q:
Does this chip support ISO14443 A/B with upto 848kbps baud rate?
I am looking for a reader chip that supports both Type A and B, upto 848 kbps baudrate,.
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Q:
Our chip is currenly limited to 212kbps. We are working on a new revision of the chip which will support (at least) 848kbps. Please keep in touch for release date of new chip.
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Q:
Can you share some details about the size/turns of the antenna you used for the 30cm read range?
The design guidelines you give on the antenna design, apart from the coupling issue do not contain information on the selection of antenna configuration for a desired read range. Are there any more references you could direct me to?
In addition, in the same application note, you mention RF overpower zener diodes used to lower the Q of the tag antenna. Is it possible for you to give more information?
Thank you beforehand,
Dimitris
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Q:
One more question on the chip:
In an application note (1W 5V power booster) you bypass the internal transmitter chain using the RES output pin in order to use an external amplifier.
Is it possible to bypass the internal receiver chain likewise? Does another RES pin serve for the same purpose?
Could you provide some more technical details on the receiver chain (I am especially interested in the AM branch). What are the specs for the bandpass filter and the receiver amplifier?
Thank you in advance
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Q:
I'm trying to write the microcontroller routines to control the MLX90121, according to the manual. However, it is not clear to me how reception actually takes place. The confusing part in the manual are the timing diagrams you include for MV reception. Do the two ISO15693 examples present a signal sequence that the microcontroller take into account, or is it an explanation of the internal workings of the 90121? I.e. does the microcontroller have to wait for DOUT to go HIGH to start polling? Is there any signal notifying of an incoming message, or should the microcontroller start polling for a response, immediately after sending a complete request?
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Q:
Im wondering if it is possible to achieve a range of 4m from MlX90121
with a 1 watt 5 volt power booster
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A:
The maximum we have achieved in our lab is 30cm, but this doesn't mean that it is the absolute maximum.
It mainly depends on the size of the antenna. So, the application mainly depends on your applcation.
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Q:
The distance uve achieved is that achieved with the help of a power booster or is that the standalone reader distance without the booster?
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A:
Yes indeed, the 30cm was acheived with the power booster.
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Q:
Can you share some details about the size/turns of the antenna you used for the 30cm read range?
The design guidelines you give on the antenna design, apart from the coupling issue do not contain information on the selection of antenna configuration for a desired read range. Are there any more references you could direct me to?
In addition, in the same application note, you mention RF overpower zener diodes used to lower the Q of the tag antenna. Is it possible for you to give more information?
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A:
The antenna we use is the one which comes with our EVB90121. The dimentions are 12 x 12 cm, one turn, Q factor of 14 and adapted on 50 ohm at 13,56MHz.
For further information on antenna design, you can refer to books such as "RFID Handbook".
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Q:
Does this chip support ISO14443 A/B with upto 848kbps baud rate?
I am looking for a reader chip that supports both Type A and B, upto 848 kbps baudrate,.
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Q:
i was just wondering did you buy the evaluation kit for the mlx90121 or you used their sample application circuit diagram to build the reader
i need some help as im planning to build the reader based on the circuit diagram provided
i would even like to know if the serial communication in the chip is sync/async
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A:
All the data I reported on the previous posts were achieved/measured on our evaluation kit. The schematic provided on the datasheet is basically the one used to develop the board.
Lastly, the serial interface works real-time and is therefore asynchronous.
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Q:
could you please advise me of the microcontrollers that can be used with this chip im planning to use a PIC 12 series microcontroller
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A:
We are using Atmel ATMEGA128 on our development kit. As far as I know PIC12 is less powerful. But again, the choice of the micro is highly dependent on your application.
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Q:
In an application note (1W 5V power booster) you bypass the internal transmitter chain using the RES output pin in order to use an external amplifier.
Is it possible to bypass the internal receiver chain likewise? Does another RES pin serve for the same purpose?
Could you provide some more technical details on the receiver chain (I am especially interested in the AM branch). What are the specs for the bandpass filter and the receiver amplifier?
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A:
Please find hereunder the answers to your questions;
1. In the "1W 5V power booster" application note, the transmitter chain is built externally. To generate the oscillation and then create the RF field, the output of the MLX90121 XBUF (digital signal at 13.56MHz) is used.
To achieve a 100% modulation depth, an internal signal, which corresponds to the modulation signal of the MLX90121, is routed out to RES2 (pin 18). To use the system with a modulation depth of 10%, the RES2 pin should be high impedance and the output carrier is modulated using the MOD output pin (pin 3) of the chip. This application requires a specific registers configuration of the MLX90121. (We will contact you for more information).
2. It is possible to bypass some blocks of the receiver chain, but it is used for test purpose only.
3. Concerning the ASK receiver chain, please refer to the datasheet of the MLX90121, page 7, "ASK Recovery" section. As far as the specifi
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Q:
how to decode the MLX90121 answer?
This is what I mean: when I do an inventory with ISO15693, I receive answers that are not identical. Example, in hex format:
Answer 1: 40 ED 55 55 55 54 B2...
Answer 2: 00 76 AA AA AA AA 59...
Apparently there are similarities and shifting the answer(s) give the "same" answer.
Here is the 1st answer shifted right by one bit:
1: 20 76 AA AA AA AA 59...
2: 00 76 AA AA AA AA 59...(unmodified)
And here's the 2nd answer shifted left by one bit:
1: 40 ED 55 55 55 54 B2...(unmodified)
2: 00 ED 55 55 55 54 B2...
Questions: which one, if either, is right? Is there any reference sources (C) for decoding the answers (ISO tags)? Acquiring the incoming bit stream is not a problem, but I don't have a clue how the UID (or any other data) is decoded from those answers. Just a simple spec what the chip sends would be help
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A:
The MLX90121 transceiver removes the carrier of 13.56MHz and the sub-carrier which composed the data (according to ISO15693 Single sub-carrier of 423.75kHz and dual sub-carriers of 423.75 and 484.28 kHz). Then on the Dout digital output of the chip the data will still be Manchester encoded and the decoding has to be handled by the microcontroller.
Following the Inventory request sent by the MLX90121, the reply of the transponder should contains 12 bytes (excepted SOF and EOF) as follow:
SOF + 1byte of Flags + 1byte of DSFID + 8bytes of UID + 2bytes CRC + EOF. All bytes are sent LSB first.
It seems that there is a problem inside your program, because the first byte (Flags) must always be to 00. Take care to correctly decode the SOF of the reply before trying to decode the rest of the data (synchronization), it is possible that a shift occurs here. To cont
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Q:
Thank you, everything seems to be in order now. One more thing: is there some sort of pre-amble in the received data, i.e. can I count on that there always is certain number of DSYNC high-low taransitions to be ignored when the receiving starts or do I have to calculate the ignored transistions? Currently on ISO15693 receiving I'm discarding first 6 high-low DSYNC transitions and after that I'm receiving the data.
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A:
The DSYNC output signal is available when the Majority Voting is started. This is done by the user (microcontroller) by setting high the CK line (please refer to the page 17 of the datasheet of the MLX90121). The response from the transponder appears 312us +/- 2us after the request of the reader and always starts with a SOF sequence. As the SOF sequence always starts with a long transition to zero followed by a long transition to one it's possible to synchronized your microcontroller on the first rising edge of SOF which appears on the Dout line. Then to decode the response, please follow this procedure:
. Send request
. Configure the MLX90121 in ISO15693 SS or DS reception (Majority Voting, DecTimeRef = 18.88us of hlaf bit ) according to the datasheet of the chip.
. Wait for 310us.
. Wake-up and poll to see the first rising edge on Dout line (means beginning of the SOF).
. Start the Majority Voting by setting high CK.
. Wait for 5 hi
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Q:
I'm having some problems communicating with the MLX90121, and maybe you can help me to locate the problem.
I would like to know, what the default power-on state is for the MLX90121. According to the datasheet, the XBUF pin should give out a 6.78MHz signal, as soon as the chip is correctly powered (and the crystal is in place).
My problem is that in 2 cases, where I soldered the chip on an experimental board, none was giving out this signal. When trying to program the chip, I eventually managed to get an output, by configuring the powerstate register to Transmitter On mode and the analogconfig register with the byte 0xA7. The latter should lead to a 13.56 MHz signal out of the XBUF.
My questions are:
1. What should I read out of the XBUF pin, upon power-up (without programming)
2. What is the recommended sequence, if any, of correctly configuring the chip?
3. Do you think the chip is faulty? I have carefully checked the connections on the
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A:
The XBUF output can be used to clock another device (e.g micocontroller) and should be active when the chip is powered ON (6.78MHz). If your application doesn't use this features, it is preferable to disable this output to avoid parasitic oscillations.
It seems that the chip is not correctly powered ON. Can you please control the following points when you turn ON the power supply?
1) The power supply is from 2.7 to 5.5 Volts
2) Every pins VDD (1: VDD1, 12: VDD2, 17:VDD3) are correctly supplied.
2) A 13.56MHz crystal is connected to the chip and a 13.56MHz signal is present on the XOUT pin.
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Q:
I do want to use the XBUF output in my application. However, on power on the following measurements have been made:
1) power supply (on all 3 pins) is 5.12V (I even experimented with slightly lower values).
2) the crystal is connected to the chip and on the XOUT pin, there is a 13.56 MHz signal of 3.52V peak to peak.
when I attempt to set the analogconfig register, XBUF goes HIGH. If I try to turn the state to PowerOn, I can monitor some 13.56 MHz noise on the power supply, due to internal switching (I would suppose). This noise is of minimal magnitude and the voltage supply stays always within limits, because decoupling capacitors have been used: a 100nf, a 10 uF (tantalum) and a 22 uF (electrolytic).
If all these ring any bells, please let me know what the problem could be. Otherwise, I'll assume that the IC is faulty or damaged and I'll try to replace it.
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A:
I think that something is wrong with the chip or with the board that you use. As measured, the VDD and Crystal signals are correct and the chip should provide a 6.28MHz oscillation on the XBUF pin after the power ON.
It seems that the XBUF output pin is broken and the chip needs to be changed. Before doing that, can you please can you check the following points?
Care should be taken that the maximum drive current on the XBUF should not exceeded 4mA. Can you check if the device connected on this pin drive too much current?
Please, also check the XBUF connection on your board, maybe it is shorcutted.
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Q:
thanks for the reply. I also thought so and I replaced the chip. The new one works perfectly.
|
Q:
I'm trying to implement the 5V power booster circuit described in your application note. I have a small question on this. The power supply of the MOSFETS is the same as the digital part of the design?
Isn't the large current consumption affecting both circuits? Would the performance be improved if there was some kind of isolation between the two parts?
How did you deal with this problem, if it was a problem at all?
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A:
Hello,
In the application note, the power supply of the MOSFETs is the same as the digital part. The 1Watt 5volts power booster works in this configuration (care should be taken to weel adjust the duty cycle of the circuit to avoid extra consumption), but it should be better to add multi-layer suppressors (MLP1206-601a) to isolate the supply of the digital and the chip to the supply of the MOSFETs.
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Q:
one more question on the power booster. I can configure the MLX90121 (via a microcontroller) according to the Application Note, to get 100% modulation (data out via RES2). However, modulation only happens if I use direct transmission mode. Using hardware encoders, the RES2 output is kept at HIGH level steadily.
Does the "special" PowerState value affect this functionality? Am I only to use the power booster in direct transmission mode?
Is there possible to use Vdd1 5V for high TX output power and Vdd2&Vdd3 3V for 3V digital interface with lowpower CPU?
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A:
In the +5Volts power booster application the internal signal MOD routed out to the pin RES2 corresponds to the modulation signal independently if you are using the MLX90121 in direct mode or with the internal symbol encoder.
To routed out the MOD signal, the following register configuration should be programmed: PowerState[6:3] = "1110".
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A:
It is not recommended to use several power supplies for the MLX90121. This may disrupt the internal digital communication and the functionnality of the device will not be guaranteed.
|
Q:
What is the advantage of the MLX90121 over
- TI S6700
- EM 4094
- Philips CL RC632
or any other reader chip?
|
A:
- Compared to the TI S6700, the MLX90121 supports ISO14443B in addition,
- Compared to the EM4094, the MLX90121 offers data pre-decoding (FSK / PSK for example) in addition. The EM4094 therefore requires a more powerful MCU to decode data,
- Compared to the CRL632, the MLX90121 offers more flexibility as the CRL632 treats all the protocol in hardware. In addition, the CRL632 is much more expensive then the MLX90121.
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Q:
Is there any power differences among the chips that you know of? Which will give the longest battery life?
|
A:
As far I am aware of the Philips is definiely power angry, the TI and Melexis are very similar and I don't know if the EM device implements efficent low power modes.
But what I know is that our device MLX90121 is been successfully implemented into battery operated systems (e.g door lock applications).
|
Q:
My company is interested in building a prototype RFID reader based on ISO 15693 protocol. Are any detailed datasheets avilable?
|
A:
The MLX90121 support ISO15693. Please have a look to the datasheet on http://www.melexis.com
|
Q:
I have already gone throu the document above mentioned. It would be quite helpful if any document showing examples of the commands from thr MCU to the reader IC were available for ISO 15693.
Along with the above enquiry I would also like know if manchester encoded signal sent by the tag is decoded by the reader hardware or is there a need to implement a decoder
|
Q:
1)There is no manchester decoder block in the MLX90121. Does the MCU needs to decode it?
2)What is the read range expected from the antenna circuit given in the data sheet? My requirement is 1meter please advice how to achieve it?
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A:
Whenever you buy the DVK90121, you get access to the drivers of the MLX9121 (but they are MCU dependant). It is also possible to get access to the ISO protocol source code.
On your last topic, the manchester decoding has to be done by the MCU.
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A:
The manchester decoding has to be handled by the MCU.
What we have experimented in our lab, for the ISO15693 protocol, is a reading distance > 20cm. With the external power booster, one can reach > 30cm.
More than this seems difficult as a first glance unless you use an external power booster associated with a - very - large antenna.
|
Q:
In case of 15693 protocol, when Symbol transmission, what is the condition to generated DSYNC signal.
In my case, after assert MODE high and RTB low, transmit SOF with CK
However I don’t see the DSYNC signal
I want to the condition that DSYNC signal is generated in Symbol transmission and MV reception
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A:
DSYNC is a synchronization signal generated when the MV is enabled. The MV will be enabled by asserting the CK line to high at the beginning of the transponder's reply.
For ISO15693, this can be done quite easily because the transponder always replies with a fixed time of 312us +/- 2us. Consequently, the external microcontroller exactly knows where the answer of the transponder is and can assert the CK line directly after the first rising edge detected on DOUT.
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Q:
I want to know the state of each pins in case of Symbol transmission and MV recepion.
|
A:
For the symbol transmission, please refer to the page 14 of the MLX90121 datasheet. Pins CK and DIN are used to transmit symbol and output DSYNC will provided by the MLX90121 to inform that the corresponding symbol has been sent (modulate on the transceiver's antenna). Please keep in mind that three CK pulses are needed to start the transmission.
For the reception with MV, please refer to the page 15-16 and 17 of the MLX90121 datasheet. As the MV is time realted, it must be synchronized on the incoming stream by rising up the CK line. Therefore, the external microcontroller needs to pool DOUT after sending the request to find the beggining of the transponder's reply and rises CK.
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Q:
But I have one more question.
I wonder why the state of DOUT PIN is high always in case of incorrect reader module.
For the correct reader module, the state of DOUT PIN is low in receiving process.
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A:
Can you give me more details about the problem? What do you mean with "incorrect reader module" and "correct reader module"?
|
Q:
All Applications about MLX90121
|
A:
All potential applications using the MLX90121 are listed on the datasheet.
|
Q:
After reading the documentation given by DVK90121, are there any more in depth information that I can refer to? For example, the Op code and parameters section, Where can I get the full list of commands? I cant design my things with just the few examples given in the documentation.
How do I input information into the TAG?
|
A:
The full list of command is related to the tag you are using. Please refer to the documentation of the tag to get relevent informations to address it. In case the tag you are using are compliant with a communication standard (ISO14443 or ISO15693) you could also refer to the related technical documentation.
|
A:
Dear Tushar Phadke
Could you precise which demo board you are talking about ?
(Please give the reference : Demo90121_LR, Demo90121_DA.. )
Sincerely
Julien
|
Q:
We are using the MLX90121 ic for reading HF tags but some tags simply doesn't respond while others work whithout problems. According to me, it can't be that they use another protocol because the tags are send to us as a ribbon of tags stitched to each other. First we thaught that there might be anticollision problems but we've cutted them apart from each other and still some tags doesn't respond.
Is it possible that we made a mistake with the CRC? You'll find a piece of our C-code on http://users.telenet.be/kennyvdn/melexis/code.txt
Kind regards
Kenny
|
A:
Dear Kenny,
The first thing to confirm is if the TAG replies to your command. This can be easily check by sampling the field of the RFID reader (with the TAG close to the reader's antenna) or with a small loop put on the TAG itself.
By observing or not the back modulation of the TAG, you know if the problem is in the command sent by the reader or in the answer of the TAG. Then, further investigations can be made accordingly.
Best Regards
Denis
|
Q:
Problem solved, it had something to do with the mask value in the inventory request
thanks anyway
Kenny
|
Q:
It seems that MLX90121 RFID Transceiver IC is no where to found in the website page. I would like to buy the mentioned transceiver IC? Can anyone give me the link in order for me to buy the MLX90121? Also, do you ship in the Philippines? Or are there any sales distributors in the Philippines or internationally? I really need this.
|
A:
You can contact our local distributor in Singapore who is also responsible for the Philippines:
EMEC Electronics Pte Ltd
3, Ubi Avenue 3, #03-02, Crocodile House
408857 Singapore
Phone +65 6744 8100
Fax +65 6744 2468
E-mail wendykoh@emecsin.com
Web www.emecsin.com
|
Q:
What is the cost and procurement procedure of MLX90121 IC. What support and information do you provide along with it?
|
A:
Thanks for you interest in our products. The best route to buy the MX90121 is to contact our sales channel: http://www.melexis.com/contact.asp.
To design the MLX0121, these are several options. Either:
- You buy samples and build directly your own system,
- You buy our DVK90121 to start with and have an example of implementation,
- You require additional support (training, consultancy, source code, ...), then contact your local representative or disti.
|
Q:
I need to design my card to link to a database..how can i do it?
I read the documentation given by DVK90121. Are there any more in depth information that I can refer to? For eg, the Op code and parameters section, Where can I get the full list of commands? I cant design my things with just the few examples given in the documentations.. Any kind soul please help me..
How do I input information into the TAG? Im really new in this field.. Please help
|
A:
Commands depend of the ISO standard used to communicate with your card (ISO14443A/B ISO15693... )(In the case you use a standardised protocol).
Standards are available from the standardisation organization of your country.
You will find in the standard all the information you need to communicate with you card.
|
Q:
Where am I going to get the full list of commands for communicating with the tag?
|
A:
the full list of command is related to the tag you are using. Please refer to the documentation of the tag to get relevent informations to address it. In case the tag you are using are compliant with a communication standard (ISO14443 or ISO15693) you could also refer to the related technical documentation.
|
Q:
Can any one help me with MLX90121 demo board. What are the possible passive R/W tags that can be interfaced with this demo board?
I am talking of Demo90121_DA
|
A:
the DEMO90121DA is intended to be used with ISO14443A compliant tag.
|
Q:
I have questions about MLX90121:
1)It is stated in the datasheet(page 8) that "For the signal that go to- and from the microcontroller: one should take care to keep them as far as
possible from the analog parts and the quartz oscillator", why is this so?
2)When in configuration mode and during symbol transmission, DIN is sampled on every rising edge of CK, what's the minimum time of sampling before DIN recognizes that it's 1 or 0? Also, can I just continue on transmitting symbols and ignore the output from DSYNC(every rising edge)?
|
A:
HEre are the answeres to your questions:
1) It is difficult to explain... It is a source of noise. When microcontroller or any other device switches any line, the noise is produced. If there is capacitive or inductive coupling, this swithing will influence the analog part and/or oscillator.
You can imagine that load modulation has a very small index. Reader makes a field and TAG modulates this field. If TAG is far away from the coil, the modulation will be very weak. Reader needs to recognize and decode this returned modulation. If we add any noise from around, the non-easy task of reader will be ever more difficult.
2) The width of CK must be a little bit less than 500ns. Let's say 500ns to be sure.
Also, can I just continue on transmitting symbols and ignore the output from DSYNC(every rising edge)?
No. Device doesn't have internal buffer. The new symbol will be lost or cause resynchronizatio
|
Q:
I'm trying to write the microcontroller routines to control the MLX90121, according to the manual. However, it is not clear to me how reception actually takes place. The confusing part in the manual are the timing diagrams you include for MV reception. Do the two ISO15693 examples present a signal sequence that the microcontroller take into account, or is it an explanation of the internal workings of the 90121? I.e. does the microcontroller have to wait for DOUT to go HIGH to start polling? Is there any signal notifying of an incoming message, or should the microcontroller start polling for a response, immediately after sending a complete request?
|
A:
The microcontroller controls the communication and must enable the MLX90121 for the reception. This is done by setting CK line HIGH at the beginning of the response (Majority Voting enables).
The microcontroller needs to poll DOUT and start MV (CK HIGH) when the first rising edge is detected (SOF is transmitted by the TAG). Once the MV is started, the data information from a TAG is ready on the line DOUT at every falling edge of the signal DSYNC (this signal can be used to synchronize the microcontroller).
In ISO15693 (Single or Dual sub-carrier), the transponder replies 312us after the request of the reader. Then, the microcontroller can wait about 310us before polling DOUT to detect the first rising edge.
|
A:
1) how tag-it (tansponder) used with mlx9012. its possible use the tag texas instruments?
2) the inventory (request cad uid function 01h) in the texas is
01h - sof
09 and 00 - length os string msb and lsb
10 - family id or device id
83 and 01 - command
9a and 65 - lrc msb and lsb
and how is command with mlx90121, ist´s possible to send example of command.
|
A:
Hi,
(1) Yes it is possible to read out tag-it transponders. The transmission protocol will be as follow:
Transmission = Pulse width modulation (Tp 11us).
The best way is to use the MLX90121 in direct mode. Then the PWM modulation signal can be sent by the microcontroller on the digital pin DIN. Microcontroller takes the control
Reception = ISO15693 Dual Sub-carrier 26kbit/s.
Please follow the register's configuration describes in the datasheet of the MLX90121.
(2) The MLX90121 13.56MHz transceiver is used to demodulate data information from the carrier and sub-carrier. The encoding (Manchester, Biphase, NRZ) and protocol level (meaning of the request/response) should be managed by the microcontroller.
Patrick Albert and his team
|
Q:
the config register need to make allways to play de circuit? or the mlx90121 guard the config to itself.
another question. the byte to send to lmx90121 is msb first or lsb? ex. (876543210) send first bit 0 or bit 8 ?
|
A:
Registers configurations doesn't need to be refreshed once programmed.
Data to be sent to the registers should indeed be programmed MSB first.
|
Q:
Can you tell me what port on the ATMega128 the MLX90121 is hooked up to in the DVK, and if this port has any special configuration? I would be able to tell from the schematic of the DVK, but I could not find it online. We want to use a CC2430 microcontroller instead.
|
A:
In the DVK90121, the MLX90121 is controlled using the portA of the ATmega128 microcontroller. The digital lines don't required a specific configuration and are toggeled according to the MLX90121 datasheet.
Therefore, all digital outputs of microcontroller can be used to control the MLX90121 transceiver.
|
Q:
Is it possible to use different voltages on VDD1 (the transmitter power supply) and VDD2 (the digital section power supply)? I ask because our microcontroller requires 3V, but we still want to get 250mW of power out of the TX. This would save having to put a level-shifter between our microcontroller and the MLX90121. We aren't using the receive circuitry at all.
Thanks!
Ben
|
A:
The transmission part of the MLX90121 is supplied independently and should be able to support a power supply of 5Volts. The only problem that I can see is on the internal logic to provide the 13.56MHz command to the driver which is connected on both supplies (Transmission: VDD1 and digital: VDD2) and may not work properly. The best think is to try if this works.
Best regards
denis
|
Q:
We want to use MLX90121 as a simple 13.56MHz transmitter (no receiving). We will use a microcontroller to turn the 13.56MHz signal on and off: when DIN is high, there should be an unmodulated 13.56MHz signal at TX, when DIN is low, there should be no signal at TX. Do you see any problem using the chip in this way?
|
A:
Your application should not be a problem. The MLX90121 will be configured in direct transmission with a modulation depth of 100%. Therefore, the corresponding value on DIN will directly modulate the RF field (high = no modulation, low = modulation).
|
Q:
Due to a quite wide range of tag-loads the RFID-antenna shows impedances that vary from 50 Ohms; therefore I cannot guarantee the RX-input-limits. I tried to use the envelope detector given in your MLX90121-cookbook, but it didn´t work. First I can see that the DC-input ist much higher than that 2-3 V so I increased R3 (RX-VDD-connection) to appr. 70kOhms which lowers the DC-voltage at the RX-pin to about 2.5V.
Even though the subcarrier-voltage has a peak-level of more than 1 V within the RF-signal the DOUT-pin is constant HIGH.
Now I use simple resistor network given in the cookbook but with 340Ohms instead of 680Ohms to get useful signals.
Any ideas?
|
A:
Increasing the resistor R3 of the external detector will reduce the DC level but will also increase the time constant of C3 and R3. This is not be suitable for a correct reception (the the stabilization time may be too big).
Anyhow, it seems that in you application, the RFID reader has to receive a quite large back modulation from the TAG (sub-carrier of about 1V peak). I am afraid that with such a big modulation, the MLX90121 enters in saturation, even if the external an external diode detector is used. The only solution is to use an attenuation cirucit like you did.
|
Q:
For details about my still existing problems I posted a few oscilloscope-pictures on my webspace. Pls. go to http://www.wissenwasser.at/mlx90121
First a few more details about my system: It has a power-consumption of nearly 40mW (yes, milli-watts). The reader- and tag-antenna have a diameter of appr. 16mm and work within a distance of 3-4mm with a coupling-factor >60%. The communication is only one-way from tag to reader. Because the tag has an µC with its own 1MHz-Oscillator I am not able to use ISO-conform subcarrier-frequencies but f_sc=250kHz.
As you may now guess it is a completely selfmade-tag with a few functions (tag.tif).
Something on your posting:
First I have to say that the R3-C3-time constant shouldn´t make problems due to the fact that communication only starts when the system is in some kind of a "static" state (appr. 300ms after Power-On).
External Envelope detector
==========================
There is one important question about the external envelope-detector: If I am right the current source at the RX-input has appr. 37uA. Therefore a 27kOhm-resistor causes an effective DC-level of appr. 4V. Isn´t that too high? The datasheet tells me an RX-VSS-voltage of max. 3V. Or is that only the AC-part? I tried to use this but in that case the DOUT-pin is permanently HIGH.
Then a question about R2-C2: The time constant will be appr. 100pF*(22kOhm||27kOhm)~1.2us. Isn´t that too slow? Even with a 212kHz-subcarrier the envelope-signal can´t relax enough. I would say that the time constant should be about the 3rd to 5th part of the half sub-carrier-period (i.e. 800ns for f_sc=212kHz - I know, that´s only 10x more than the 13.56MHz-period)
Majority Voting
===============
Furthermore I found out that using the Majority voting seems to have an influence on the data quality: Without MV activated all data can be well detected (shown on the oscilloscope; see PRINT_03.TIF). But if MV is active nearly the half of all data that should be interpreted as LOW is returned as HIGH (no picture available).
Please take a look to Picture PRINT_02.TIF. It has been taken using the resistor-network for RX given in the cookbook but with 340Ohms instead of 680Ohms.
Because the received signal quality is sometimes really bad I used 68us-syncronisation bits followed by 36us space and then 36us for each data bit. The upper part shows DOUT without MV. Btw. the lower signal is the ANT-pin with nearly 1V peak. As you said the receiver is in saturation in that case. Is that right?
PRINT_03.TIF shows one sync-bit. The CK-pin is LOW until my reader-uC detects HIGH at DOUT for at least 68us.
If you are still with me I would like to know your opinion about the schematic (schematic.tif) of a possible solution for both AC-levels (regular signal and subcarrier-signal):
As I wrote the tag-reader-coil-distance is within 3-4 mm variing about 1mm which causes big differences in the signal strength. Therefore I was thinking about a possibility for a signal levelling.
The first and last part of the schematic are like your external envelope detector given in the MLX90121-cookbook. In the middle there is a Schmitt-Trigger. The AC-input is raised to the half supply-voltage by R9 and R10. The low-pass filter R2-C2 has a big time constant so that the input signal is damped. The Schmitt-Trigger-levels are set to +/-25mV of the AC-input. At the output the rectangular signal is reduced to appr. 100mV peak-level and AC-coupled to the RX-pin.
I know that´s a little bit extreme but it should solve the problem with the input-signal-saturation.
But at least the most important things compressed:
*) DC-input range of RX-pin?
*) AC-input range of RX-pin for 13.56MHz and the subcarrier?
*) What about the problems found with Majority voting?
|
A:
As I can see, the MLX90121 plays its role by integrating the sub-carrier frequency to provide the base band signal on DOUT (the data rate is a multiple of the sub-carrier frequency).
If the communication is made without any sub-carrier frequency (data rate at 250kbps), I would suggest you having a look to the MLX90121 cookbook (available on our web-site) to the chapter "Support of different modulation modes". A specific register’s configuration must be programmed for such specific communications.
I guess the problem with the majority voting (MV) is also linked to the register's setting. The MV is time related and therefore must be started by rising-up the CK pin at the beginning of the reception (synchronization). Moreover, the time DecTimeRef must be programmed according to the data rate to receive.
|
Q:
We are designing a MLX90121-based board that uses the "power booster for MLX90121" circuit to transmit 1.6W. I am having trouble deciding which specific inductors and high voltage capacitors to use. Can you indicate which components for this circuit you have had success with (manufacturer/part number)?
|
A:
Please find below some examples of the type of components used:
INDUCTANCES EPCOS FARNELL: 512370
CAPACITORS 50V NPO FARNELL: 718506
CAPACITORS 100V X7R FARNELL: 7568649
|
Q:
The operating temperature range of the MLX90121 IC is specified in the datasheet, but do you know the same for the IC plus application circuit plus 5V/12V power amplifier (from "A Power Booster for the MLX90121")? Even a best guess would be useful.
|
A:
We only provide specifications on our product ICs with several application notes which develop some specific solutions. But, the module provider must take care about the specification of the module combining the MLX90121, the antenna and all the components around the device.
As I know, most of the product now supports a temperature range from -55 to 125 degrees. But, I never checked if the components of the 5V/12V power amplifier can support it.
|
Q:
I am using a custom made RFID-circuit based on the EVB90121 (resp. the circuit given in the MLX90121-datasheet).
Even though I already replaced the SMD-inductors (too high ohmic resistance; >1 Ohm) I cannot get the ouput power of 250mW.
For testing the ouput I use a 51 Ohm-Resistor directly at the ouput. Tuning the circuit to get a nice sine-wave works very well, but the peak-peak-voltage ist only 7.4 V which means a power of 136mW.
What could be the reason for that?
By the way: Also VK200 and tantalum-caps (with X7R-caps in parallel) in use. Ripple voltage < 500mVpp.
|
A:
Most of the time, the inductors which composed the matching network is the reason of a power reduction.
Please be sure that the inductors your are using don't have a too poor quality factor (below 45-50) resulting in a quite high serial resistor which will dissipate some extra power.
Moreover, the position on your board of these inductors have to be verified to avoid to have two parallel inductors close together. Otherwise, the matching may not be correct due to extra coupling between these inductors.
|
Q:
First of all: Coupling was not the problem but a too low quality factor.
I replaced one coil with one directly from the EVB90121 and it worked.
Furthermore it seems that using 4.7uH instead of 5.6uH leads to a better signal.
But one question: I took a look to different distributors and found that in the best case a quality factor of 60 is available.
My first coils should have had a value of 50 but that seemded to be wrong.
Could you tell me who is the producer of the coils (1.2uH, 4.7uH, 5.6uH) in the EVB90121?
|
A:
Please find below the Farnell reference for the coils used in our evaluation board EVB90121:
1.2uH : 508561 (Q = 55 @ 7.96MHz)
4.7uH : 608464 (Q = 60 @ 7.96MHz)
5.6uH : 509929 (Q = 60 @ 7.96MHz)
|
Q:
is possible to supply the MLX90121 VDD inputs from a different voltages? Typically, VDD1 (and VDD3) from 5 volts to achieving higher output power, and VDD2 from 3 volts to matching digital I/O lines to 3 V microcontroller enviroment? Are there any internal couplings betveen VDD pins? I haven't found this information from datasheet.
|
A:
It is not recommended to supply the MLX90121 with different power supply values. This to avoid extra currents in the substrate which will degrades the performances of the device. Therefore, 3Volts or 5Volts should be used to supply Vdd1 & Vdd2 & Vdd3.
|
Q:
we're currently re-designing a battery powered hotel door lock system based on iButton and contact smartcard keys. In order to achieve a reasonable battery lifetime the Ptot limit for this (contact) version is below 10 micro W. Having read the 90121 datasheet I'm looking for a way to use a one antenna design to power up/down the device upon "seeing" a 13,56 MHz tag(antenna).
Thomas
|
A:
The feature you are looking for is called "tag detection". We had some idea to implement it with the MLX90121.
|
A:
thanks for your quick response ! At the moment I'm playing around with a FET oscillator and a MAXIM nanowatt OpAmp but I doubt very much that this circuit will work when connected to the _same_ antenna as
your 90121
|
Q:
Is it possible to use the MLX90121 with a subcarrier frequency of 250 kHz? I know this is not ISO-compliant but it should within the detector´s possibility. Furthermore the bit-time is 20us. What is the necessary analog configuration for that case (AM)?
|
A:
The high flexibility of the MLX90121 allows to use none standard sub-carrier frequency.
For more information, please refer to the cookbook of the MLX90121 on page 19 (Support of different modulation modes).
|
Q:
With an antenna size of 9cm x 6cm and a round 24mm transponder, what would be the read distance using your MLX90121 with or without the 1w boost?
|
Q:
I need a distance of around 10 inches. Is this ppossible?
|
A:
As an example, with a 1Watt MLX90121 reader, a 12x12cm antenna and a credit card size transponder, we are achieving about 15-17 Inches.
The area of you transponder is 4 times smaller. As a first approximation, the operating distance will be 4 times smaller to about 4-5 Inches.
Therefore, I am afraid it will not be possible to achieve 10 Inches with a so small transponder size, even if you are using the 1Watt power booster.
|
Q:
In your cookbook for the MLX90121 you have a 1 watt 5v power booster circuit. Could you tell me the manufacturer part number for the C1 that goes with the L1 132-11SM?
Does this circuit come with any of your development kits?
|
A:
You can find Mica capacitors from Farnell (www.farnell.com). The part number is the following 1264890.
The 1Watt power booster versions of the MLX90121 are not provided as an evaluation board. Application notes must be followed to build the 1watt solution.
|
Q:
I cannot find any real world example of the antenna circuit for the MLX90121 in the data sheet or AN, there are only theoretical articles. I need a quick initial start from where I can work on.
Could you therefore please send me the circuit diagram of your EVB and the PCB-antenna that you used in the DVK90121? That should be a good basis to start from.
I need to design a small PCB-antenna as well.
What is the output impedance of the RX ?
What needs to be done to keep the spurs within legal limits? How much does the TX generate?
|
A:
The schematics of the EVB can be found in the associated documentation which can be downloaded from the MLX WEB.
We don't provide the schematics of the antenna on line, as we had the belief that it was too applicaion specific.
However, as we indeed have more and more requests for assistance in this area, we decided a couple of weeks ago to include the schematics of the antenna, as par of a general upgrade of our documentation.
As far as FCC/EN compliance, we have nothing that could be made publicly available. But again, if the market calls for it ...
|
Q:
I need to design a board directly into our system. So getting a EVB does not help me a lot, it would just take me longer to get the task done. Couldn't you just put the diagram of the antenna section online? That would speed up things a lot.
Concerning EN & FCC, I know it's my duty. But as an example, your colleagues at Philips recommended in an AN an antenna circuit for their IC, so that we could easily pick up from there and knew what to do to make it complient. After all the information is available in your company, so why not communicate it to your users?
Convinced ? :-)
|
A:
You are correct. What Melexis provides are only examples of antenna and matching networks. It is usually sufficient for our customers to start with.
My advise is for you to purchase the EVB90121. the circuitry comes with the documentation. Please contact your nearest MLX distributor.
As far as meeting the FCC or EN requirements, this is application specific and therefore remains under the responsibility of our customers.
|
Q:
How can I some data on how to design the loop antenna ?
|
A:
You can find some useful information in the application note "13.56MHz RFID systems and antenna design guide" available on our WEB-site.
|
Q:
Where to buy?
|
A:
You can check with our disti's Digikey or Future or contact you nearest local representative, www.melexis.com/contact.aspx
|
Q:
i wonder if c210 rfid tags from Tagsys can work with reader built with mlx90121? b/c i am not quit sure c210 meets iso15693. does anyone have experience with this sort of tags?
|
A:
The C210 from Tagsys is a one time programmable OTP transponder which doesn't complies with the standard ISO15693 ("TAG talk first" transponder). The transponder will reply with its identification number when putting in the RF field.
I have no more information concerning the sub-carrier and the protocol used.
|
Q:
How does the MLX901212 detect a collision?
|
A:
The MLX90121 is unable to detect a collision y itself. The anticollision procedure has to be handled by the software.
|
Q:
I'm using MLX90121 to build a vicinity reader for ISO15693 tags.
I've been trying to configure the MLX90121 but still it's not responding.
What i tried was to set the XBUFSel bit in the AnalogConfig register and see whether the the XBUF output becomes 13.56MHz. here is the code segment i used.
void initial_settings(){
int initial[12];
initial[0] = 0x0101; // power mode 0000 0001 0000 0001
initial[1] = 0x0047; // analog config 1000 0111 XBUF enabled, MOd index 100%,450K sub carrier, bypass all
initial[2] = 0x0301; // digitalconfig 0000 0001 MV disabled, AM no sub carrier, hardware encoder enable
initial[3] = 0x04BF; //encodersym 0
initial[4] = 0x05EF; //encodersym 1
initial[5] = 0x06FB; //encodersym 2
initial[6] = 0x07FE; //encodersym 3
initial[7] = 0x087B; //encodersym 4
initial[8] = 0x09DF; //encodersym 5
initial[9] = 0x0A1F; //encoder time ref 0001 1111
initial[10] = 0x0B7F; //decoder time ref 0111 1111 not needed cause MV is not used
initial[11] = 0x0C3F; //LTC 0011 1111 LTC enabled
write_config(initial,12);
}
void write_config(int *config, int length){
int i;
for (i=0;i> (length-i));
CK = 1;
delay_us(5);
CK = 0;
}
But still the XBUF output is 6.78MHZ.
Is there something wrong with the code?
|
A:
sorry abt the clarity of the above mail. this is my code segment.
void initial_settings(){
int initial[12];
initial[0] = 0x0101; // power mode
initial[1] = 0x00C7; // analog config 1000 0111 XBUF enabled, MOd index 1
initial[2] = 0x0301; //digital config
initial[3] = 0x04BF; //encodersym 0
initial[4] = 0x05EF; //encodersym 1
initial[5] = 0x06FB; //encodersym 2
initial[6] = 0x07FE; //encodersym 3
initial[7] = 0x087B; //encodersym 4
initial[8] = 0x09DF; //encodersym 5
initial[9] = 0x0A1F; //encoder time ref 0001 1111
initial[10] = 0x0B7F; //decoder time ref 0
initial[11] = 0x0C3F; //LTC 0011 1111 LTC enabled
write_config(initial,12);
}
void write_config(int *config, int length){
int i;
for (i=0;i<length;i++){
MODE = 0; //config mode
CK = 0;
RTB = 0;
delay_ms(1);
write_single(config,12);
config++ ;
}
void write_single(int *pbuf, int length){
int i;
for (i=1;i<=length;i++){
DIN = (*pbuf >> (length-i));
CK = 1;
delay_us(5);
CK = 0;
}
|
Q:
I need to design a reader which works in a range of about 1m using ISO16593 tags and this reader will need to work in a conveyer belt. This implies that i would need to design a power booster and a custom antenna. Can you please give me the necessory resources needed for this application. Thnx
|
A:
You could refer to our last demonstrator called DEMO90121LR:
http://www.melexis.com/General/General/DEMO90121LR_662.aspx
This kit is an example of a 1W power booster implementation. It achieve reading of ISO15693 cards up to 30cm with 12cm*12cm antenna.
You will find lots of information in the related User Manual.
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Q:
I am trying to communicate between two MLX90121 using Direct Tx/Rx. The following is the initial configuration
Analog Config(0) = 0x87
Power State (1) = 0x1
After this I am sending the data by setting the DIN pin. On my spectrum analyser, I could see the Tx signal from the first MLX90121 but the Dout pin on the MLX90121 that is configured as the receiver is not responding properly. I have some spurious signal always present in that pin. Any help with setting up the MLX90121 for direct tx/rx will be greatly appreciated.
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A:
The configuration of the MLX90121 will depend to the type of communication used (data-rate, sub-carrier, ...). For more information, please refer to the application note "Support of different modulation modes" in the cookbook of the MLX90121 on available on our web site.
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Q:
I started using my 90121 DVK alongwith Eval baord
I encountered following issues
1. On my software interface, it does not show any Tab for Description in the portion next to "Command" and "Comment" Tabs as it has been mentioned in user guide
2. It does not show "Command Editor" panel either so that I can edit or write own commands.
3. there is not the drop down menu to select the Tag type but i beleive same function can be achieved by selecting the command list ( in my software i have list of different commands sets : for example, ISO14443A, 14443B , single carrier, double carrier ASK etc.
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A:
We indeed upgraded recently our software to make it more user friendly and allow automatic upgrades from our WEB servers.
I seems that our shipment to you was just in the middle of the transition period. You received the new software and the old documentation. Sorry about that.
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Q:
it seems that writing the registry for entering the PowerState Down is only working if writing the registry first with Idle Mode and then Down mode. Writing the Down Mode only doesn't work. Is there an explanation about this ?
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A:
There is no specific procedure to go in power down mode with the MLX90121. This mode can be accessed either in Transmitter On or Low Power modes.
Please note that in Low Power mode, the analog circuitry is set off but, the 13.56 MHz oscillator is still running.
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Q:
Thanks for your two answers. It doesn't help us a lot nervetheless, as all this is clearly described in the datasheet. We verified this several times and for the Power Down Mode, going from Transmitter ON to Power Down directly is working randomly. The digital lines are as needed and checked with a logic analyzer. Any idea ? Chip waking up directly for some reason ? These are just registers to be written too so I don't understand how we can experience these problems. We have the problem on two different pcb's, so it doesn't seem to be related to glitches or bad transmission lines.
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A:
It seems that the transceiver is waked-up by parasitic pulses on the CK line. So please keep the line DIN high (firmware) during all the power down time. And be sure that the line CK and DIN are stable during this time.denis
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Q:
Hi everyone there. I'm looking for a ASK, PSK & FSK transceiver which can operate from 100MHZ to 500MHZ. I saw this IC can only support to 13.56MHZ. is there any idea to increace the frequency range for this IC up to 500MHZ. thanks for help in advance :)
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A:
Ths is a very interesting question. We indeed have more and more requests from customers to modulate directly the 13.56MHz carrier frequency of the MLX90121.
All these people forget too easily that the MLX90121 has been desgined for RFID applications, as the name tells in the datasheet.
The MLX90121 RFID transceiver is built to send/receive Amplitude Modulated informations to/from the transponder. This Amplitude Modulated signal compose a digital sub modulation at 847kHz or 424kHz or 484 kHz according to the ISO standard used.
But in any cases, during the RFID communication, the carrier frequency is fixed at 13.56MHz and by no means the MLX90121 is able to change this frequency.
I hope this clarify the situation.
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Q:
i used a external uC to drive the evb90121. the configuration is iso 15693 fsk, 10%modulation as page 23 of MLX90121. i used symbol 1 out of 4 and send a request:
SOF-00001001(sym1-sym2-sym0-sym0)...EOF(lsb first)
wait about 300us
set CK high about 2ms
but no response in dout
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A:
It seems that you didn't send a comprehensible command to the transponder and it doesn't reply. In ISO15693 protocol, commands always start with SOF + 1byte of Flag + 1byte of command (opcode) + some parameters according to the request sent + 2bytes of CRC end EOF.
For easy development and understanding of the protocol, you can buy our development kit DVK90121 which includes the complete software for ISO15693 and ISO14443 communication.
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Q:
i have bought EVB90121, i want to study about it and have severe question:
EVB90121 make Send Request or by microcontroller ?
and if uP make send request, struct of send request?
(for iso 14443A,B; 15693)
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A:
You will need an external uC to drive the EVB and send the request.
Protocol software comes with our DVK90121. Maybe it is best if you buy the DVK.
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Q:
What is the input capacitance of the XIN and XOUT pins of the MLX90121?
....... Can I use a crystal with a specified load capacitance of 8 pf if I use 15 pf caps to ground rather than the 22 pf caps that are shown in the reference design?
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A:
We just measured the the values on our bench:
- Capacitance on Xout vs. Vss_tx: 2.37pF
- Capacitance on Xin vs. Vss_tx: 2.16pF
Ps. Why don't you simply use the values we recommend ?
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Q:
As far as I can tell, all of your reference designs use 22 pf caps to ground on either side of the crystal. I cannot find a recommended load capacitance rating for the crystal in any documentation. What is the value of load capacitance for the cystal that you recommend? =============================================
My motivation for using different values of capacitance was so I could use a very small crystal that has a load capacitance spec of 8 pf.
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A:
Usually, it is the manufacturer of crystal who recommends the capacitance. So, if the manufacturer of your quartz advises to use another capacitor, you should use it.
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A:
from where i could buy dvk90121???
please i need your help
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A:
our IC's and tools are available through our worldwide distributors, Digikey or Future Electronics or contact your local representative via the website, www.melexis.com/contact.aspx
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Q:
I am trying to develop a ISO 15693 reader.First I am
sending data to the 13 configuration registers of the
MLX90121 for ISO 15693 standard(FSK, High Baud rate &
10 % modulation). Thereafter I send the 6 symbols for
1 out of 4 mode, in the same order described in the
datasheet. That is, Sym0,Sym1,Sym2,Sym3,Sym4,SOF & EOF,
with their 3 bit address.Is that right?
OK, Now, what do I have to do to send a ISO 15693
command to the tag from the reader? ( I know the ISO
15693-3 protocol formats but don't know to implement
them using MLX90121).
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A:
The registers configuration, as shown on the page 22 of the datasheet, already contains the six symbols of the programmable encoder EncoderSym0 to EncoderSym5 as well as the symbol length EncTimeRef as defined in the page 11 of the datasheet.
The corresponding symbol with will be sent to the power amplifier of the MLX90121 (modulation) by following the procedure describes in the datasheet of the MLX90121 (please refer to the chapter 11.3.1.c Hardware Encoding Transmission). The micro-controller needs to manage this procedure.
The symbol will be sent successively according to the command, example : SOF (Sym4) + Data (...) + EOF (Sym5). A detailed explanation of the 1 out of 4 communication can be found in the standard ISO15693 level 2 page 6 (7.2.2 Data Coding mode : 1 out of 4).
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Q:
We are designing the reader for ISO15693 protocol with the IC MLX90121 and we required a range of 1 meter. So i wanted to ask that is this possible to get the range of 1 meter. We have got success in achieving the range of 25 cm but this range is with out external amplifier, only with 200mWatt. When we are using the external amplifier (as mentioned in your document) we are getting the out put power of 1 WATT but the return path is not working properly. Now we are not able to increase the range. so please sir if there is any optimize solution for this return path than reply to us. I also wanted to know that what is the maximun range we get with the 1 watt power, and with which antenna(size specification), can we drive an antenna of the 1meter by 1meter size as per our applications.
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A:
With a 1Watt power booster and a rectangular antenna of 30x15cm we got about 45cm of reading distance using the ISO15693 FSK standard.
Getting up to 1meter will be very hard and a very large antenna as well as a bigger output power must be used. Unfortunately, we don't have such a specification to provide to you at that time.
About the return path of the 1Watt power booster, we would need more information to answer this appropriately.
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Q:
Is there any reference design of letting 2 MLX90121 talk to each other?
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A:
No, we do not have such reference design because the MLX90121 is not capable of peer to peer communication as defined by the NFC-Forum.
The MLX90121 is able to support communication with tags compliant with ISO14443A and B and ISO15693 standard protocol and some propriaitary protocol.
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Q:
We would like to use Pspice to simulate the output stage of the MLX90121, so as to work on amplifier designs. Can you provide any additional details about the output stage of the MLX90121? We know from the Cookbook that there are two MOSFETs - perhaps just knowing which discrete type they are similar to would be enough.
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A:
The output driver of the MLX90121 is a Class-E Power Amplifier (transistor switched On/Off at 13.56MHz). For your P-Spice simulation, you can use an ideal switch with a serial resistor of 5-ohm as specified in the datasheet of the MLX90121. A small capacitor of about 15pF can be added in parallel to the switch.
For the 100% of modulation depth, the ideal switch is set OFF while, for the 10% of modulation depth, an additional resistor of about 10-ohm (RMOD) will be added in series to the 5-ohms.
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Q:
My question is about the MLX90121 configured for the ISO 14443-B standard.
What is the minimum required transition time between transmission mode e reception mode ?
Being more specific, first it's assumed the IC is in the transmission mode. The IC is receiving the symbols by the Din pin (triggered by CK). So soon it has been send the last symbol for transmission (EOF) the IC must be switched immediately to reception mode. My question is: how long after the pins MODE e RTB were switched from transmission mode to reception mode will be the IC able to decode the information send back by transponder ?
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A:
After sending the corresponding command, the analog chain of the MLX90121 will required few times to be completely stabilized.
This stabilization time is less than the typical 75us of FDT required by the standard ISO14443B.
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Q:
I am building the 1W 12-15V power booster from the MLX90121 Cookbook, and I have three questions:
1. How much power is dissipated in the resistors? (Standard 0805 resistors are 1/8W);also applies to the external detector in the reciever part.
2. How can i find the EMC radiation limits?
3. For a Q-factor of 5.7, I have calculated the component values: 3.3uH, 5.6uH and 63pF (variable). Is this correct?
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A:
With an output power of 1Watt (20Vpp on a 50-ohm load), standard resistors 0805 can be used for the transmission and the reception parts of the power booster.
If you plan to use higher output power, it you should increase the power dissipation of the resistor RMODE up to 200mWatt. You can keep standard one for all others.
Please don’t forget that the resistor of the antenna, which fixes the quality factor, should be able to dissipate ALL the power transmitted. Therefore, for 1watt you have to use at least a 1watt resistor.
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Q:
I have two questions about MLX90121:
1. According to P22 of MLX90121's datasheet after set up (15693 ASK 6Kbit/s 100% is modulated), D-OUT foot will output the pulse signal without law , Could you tell me whether it is problematic or not?
2. How is the flow chart of the received signal?
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A:
The MLX90121 provides the data bit level to the external microcontroller. Therefore, in case of ISO15693, the external microcontroller is in charge to decode the Manchester and to treat the protocol level as describes in the documentation ISO15693-3 (Read Single Block, Read AFI ...).
For the ISO15693 ASK, the transponder replies using a sub-carrier of 423,75kHz encoded in Manchester with a data rate of 6.62kbit/s. Therefore, the half part of the bit will modulated with the sub-carrier (32 period) while, the other part of the bit is not modulated. For the byte configuration, please refer to the documentation ISO15693-3.
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Q:
I have a working circuit based on the MLX90121 and ISO15693 and the demoboard DEMO90121LR.
1. How can I estimate the range I should expect? Is there a relationship between antenna size and range that could be used to compare our performance relative to the demo board?
2. Any suggestions for determining the limiting factor in the detection range? Currently I can see the tag responding (on a spectrum analyzer) further away than the tag is being detected, so does this imply the VICC to VCD communication is the limit?
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A:
With the power booster configuration, the operating distance you can expect should be between 25 and 27cm (with the DEMO90121-LR). Of course this operating distance may depends on the antenna dimensions and the TAG's properties.
As an example, with a bigger antenna (15x30cm), up to 40cm of distance could be reached.
At very long distance, the answer from the TAG starts to be distorted(due to very small power supply). When the distortion is too big, the reader cannot recover the correct information. That's why you can see a small hysteresis where the TAG still replies but with a "wrong" information.
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Q:
In my case the antenna must be smaller (roughly 3.2cm by 3.6cm). Is there any way to estimate the range I can expect from this size of an antenna, assuming a similar construction to the DEMO90121-LR?
Was the antenna for the DEMO90121-LR board made on a low loss substrate, or just standard FR4?
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Q:
I'm new to RFID tag readers so I hope the following isn't too naive. Can you tell me if I am on the right track?
Since the tag is magnetically coupled to the antenna it seems that the range will be determined by the magnetic field strength. Magnetic field strength for a small loop antenna is –B^2 * S * I * e^(-j*B*r) / (4*pi*r), where B is the plane constant, S is the loop area, I is the loop current, j is sqrt(-1), and r is the radius/distance. If my reasoning is correct then the magnetic field strength is proportional to loop area, and I should be able to plot |e^{-j*B*r)/ (4*pi*r) | to compute how much the radius must be adjusted to compensate for changes in loop area.
What do you think?
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Q:
I recently ordered the EVB90121 evaluation board containing the MLX90121 RFID transceiver, and during development and testing, I realized that the MLX90121 datasheet makes no reference toward how one can read the IC's configuration registers. Waveforms show how to write to these registers, but not how to read from them. Is it even possible to read these configuration registers? If so, would it be possible to get sample waveforms showing how to perform these reads. If it is not possible to read from the configuration registers, is there another way to make sure what is being written to the registers is in fact being written properly?
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A:
It is not possible to read the registers of the MLX90121. If the microcontroller follows the time specifications describe in the datasheet, this write operation will not be a problem.
A solution to control that the communication between the microcontroller and the device is not broken should be to sense the RF field or another output (Xbuf for example) to see the effect when you write the corresponding register.
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Q:
1. With the 1W Power Booster, what is the reading range with 45X45mm tag?
2. What brand of tag give the longest read range?
3. What is the antenna size for that reading range?
4. With 1W of Power what is the maximum size of Reader antenna?
5. What antenna material give the best reading range?
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A:
1: With the 1W Power Booster, what is the reading range with 45X45mm tag?
A reading distance of 26 cm (using communication protocol ISO15693 dual sub-carrier) has been measured with the MLX90121 1watt power booster schematic and a 120x120 mm antenna (Q=14). The transponder used has been built with an antenna of 45x45 mm and 10 turns.
2. What brand of tag give the longest read range?
The read range depends on several parameters such as the size and the form of the antenna (area, number of turn), the quality factor Q, the way of data communication (sub-carrier, modulation type). For standard communication at 13.56MHz, the best read range has been archieved with a credit card transponder which communicates in ISO15693 protocol.
3. What is the antenna size for that reading range?
A really large antenna such as door antennas can be implemented to achieve up
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Q:
4. More question on this topic.
Do you have application note on how to match a single/multiple turn copper wire antenna to 50 ohm?
What matching method do you use to match the 120X120mm antenna to 50 ohm impedance? Capacitive matching? transformer matching?
How do you measure that the output impedance of the evaluation board is 50 Ohm?
Is the output impedance of the evaluation board purely resistive? No capacitive or inductive element in it?
Do you have to build the external diode detector for the RF receive part?
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Q:
Some more information on your questions:
Do you have application note on how to match a single/multiple turn copper wire antenna to 50 ohm?
--> We have no application note about the matching of our antenna available.
What matching method do you use to match the 120X120mm antenna to 50 ohm impedance? Capacitive matching? transformer matching?
--> For the 12x12 cm antenna we use a differential capacitive matching network to get real 50 ohms load.
How do you measure that the output impedance of the evaluation board is 50 Ohm?
--> We measure the antenna in reflection using a coupler and a network analyzer.
Is the output impedance of the evaluation board purely resistive? No capacitive or inductive element in it?
--> This is the target to get a resistive 50ohms load at 13.56MHz to avoid parasitic reflections into the cable. Of course, the tolerance of all components which c
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Q:
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Q:
What is the recommended voltage at the RX pin of the MLX90121
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A:
In order to avoid the saturation of the internal diode detector, a peak to peak voltage of maximum 3 volts should be applied on the Rx pin of the MLX90121. This voltage is fine adjusted with a serial resistor between the antenna and the Rx pin. On the Melexis evaluation board EVB90121, this resistor is currently set to 4k7ohm.
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Q:
Please help me with decoding the data from the MLX90121. I am trying to read the UID from a ISO14443A card. I have set the chip up for ISO14443A as per your datasheet and majority voting. When I send the REQA command I am getting a response from the MLX90121 but I am not certain how to process the DSYNC and DOUT signals.
Have you any information on how to decode the data?
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A:
did you had a look at the App note named "Communication with ISO standard"? You will find a precise description on synchronizing and decoding the signals from the MLX90121. There is an example with ISO14443A which could interest you. Tell us if it does not answer your concern.
The link to the app note:
http://www.melexis.com/prodfiles/0005103_AN90121_10.pdf
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Q:
Yes, I have read the App note named "Communication with ISO standard" and it has been very usefull. The part I am not certain about, is how to process the DSYNC and DOUT data. How do I decode the SOF, one's and zero's and EOF from the DSYNC and DOUT.
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A:
The first thing you have to do is to synchronize the MLX90121 on the received data. This can be done by polling the signal on DOUT and rising the CK pin when the first rising edge is detected.
Then, according to the register setting, The majority voting block is started and provides you with the decoded and filtered data on the pin DOUT as well as a synchronization signal on the pin DSYNC.
The MLX90121 doesn't include a frame decoding machine. Therefore, the external microcontroller must decode the incoming data according to the type of communication used. The symbols (SOF, EOF, CRC) and parity check are defined in the corresponding ISO standards (14443, 15693).
As an example, the page 7 of the application note"communication with ISO standards" shows the SOF in ISO15693 Single and Dual sub-carrier with the decoded data on DOUT.
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Q:
I have inherited a circuit with an MLX90121 and a 1.5W power stage that follows the Melexis application note.
The transmission stages seem to work fine; I checked the signal with a scope, and with an improvised antenna (scope probe loop). I can generate pparently good 1-out-of-4 Inventory requests.
My current problems are with reception. The reception pin RX is connected via a wire and a 4K7 resistor to the antenna input that carries the signal.
Now, whatever configuration I try, I see a noisy signal on the reception signal pin (scattered 1s, each for a short time). This is independent of presence or absence of tags in the vicinity of the antenna! Needless to say, it doesn't resemble the pattern generated for a tag response, that should be 0 and 1 in equal amounts.
Am I right in supposing that there should be silence if there is no tag? Or are there known sources of interference (like a computer monitor)?
How can I figure out if the Melexis reception stages are working correctly?
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A:
It seems that you have a 1.5W power booster. In this case it is not enough to connect the antenna output to the RX pin via 4.7k resistor. The amplitude is so big that can ever damage the mlx90121. Try to use external detector solution (described in page 8) for better results.
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Q:
I fitted in the 'easy' attenuator circuit with the 3 resistors. My scope says there is a 13.56MHz signal on the input to RX, which oscillates between -0.5 and +1.5V.
The digital output is still the same: seemingly random 0s and 1s, irrespective of the presence of an RFID tag. So, alas, no progress.
Would it help if I try to fit in the external detector described on page 8? Or should I conclude that my MLX90121 is damaged (always keeping in
mind the possibility that I misconfigured, even for 'direct reception',
of course).
Correction: the signal oscillates between -0.5 and
+1.0V. It is not a good sine shape, either.
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A:
The external detector works better than a 3-resistor solution. Though a 3-resistor attenuator should also work (hopefully), you will have better performance with an external detector anyway.
Without the register information it is difficult to say anything.
For now, I can tell that it seems that system just oscillates. In this case you can have a strange signal on DOUT which changes like crazy.
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A:
I developed a reader circuit similar to that of the circuit in the data sheet of MLX90121 with a loop antenna for near field communication. I'm using a DS89C420 uC to control the communication. This will be used to implement the Tag-it protocol for TI tag and extract the SID number. Now, please fill me in if there's something lacking in what I did or correct me if there's something wrong.. At first I verified if I can configure the chip by enabling and producing an output on the XBUF pin be it a 6.78MHz or 13.56MHz. To make it really convincing I configured the DecTimeRef also and verified all of it in a oscilloscope.. In transmission, I configure the chip to 100% and I would suppose it is in ASK for direct mode. Then do a field activation(carrier freq presence) for 1ms and transmit the request using pulse width modulation as stated in the protocol. By the way, the request that I used is the example stated in the documentation of the Tag-it protocol for SID poll request. I verified my all timing and all are fine.. One thing that I noticed is that I can see 13.56MHz carrier in the TX pin as well as in the spectrum analyzer by coupling the my loop antenna with another antenna connected in the spectrum analyzer.. From what I saw there is no ASK modulation taking place. I tried to simulate a 13.56MHz, ASK, 100% using a signal generator, the waveform is different from that of my reader. Next while transmitting, I can see that there were signal output from DOUT pin, is this really something to expect during transmission. When I combined reception, which requires to wait 311us for the tag response and using dual subcarrier, I could still see the same signal from the DOUT pin regardless of the presence of the tag and I don't think it's the expected response from the tag. I also used majority voting reception but still same scenario except that DOUT signal changed to the timing of DecTimeRef.
I would like to ask what's the proper sequence for configuring and setting up the chip for direct transmission and reception? What's the best method to use during reception? My reception is my biggest problem.
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A:
Answer to the person who uses DS89C420
First of all some questions.
Do you use the programmable encoder of the mlx90121 or you use it in direct mode?
Can you send me register configuration?
In some cases the signal output on DOUT during transmission is normal. This is because the receiver part is still working and output what you are sending.
There is nothing special in configuring chip except what was described in the datasheet.
For the reception it is better to use the internal decoder (for transmission - internal encoder), it will save a lot of microcontroller load.
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Q:
I'm now able to see the modulation in the scope during transmission.. I tuned the antenna loop and configure the chip for direct mode both transmission (pulse width modulation) and reception (FM - just like what it says in the protocol). During reception, the spectrum analyzer tells me that the two subcarriers shift with the presence of the tag and when I remove the tag, it goes back to normal. In the DOUT, I can see square wave output of approximately 0.6V with ripples. Here, I would assume that the tag is now giving out a response.. As you said direct mode gives more load to the uC and I'm thinking that it will also give me a hard time designing the code for decoding the response.
Will it be easy in the design of the code if I use majority voting in junction with the internal decoder, since it uses DSYNC for synchronization. In using the majority voting w/ internal decoder or just internal decoder, are the output from DOUT manchester encoded (1to0 and 0to1) or are they immediate data bit (1 or 0). The other thing is that the patterns of the SOF and EOF of the Tag-it protocol are different from the ISO15693.
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A:
Using internal decoder (means majority voting MV) will provide you a synchronization signal DSYNC to easily get the filtered data from the MLX90121. Consequently, the load of your microcontroller will be reduced.
Nevertheless, the MV needs to be started by the microcontroller by rising the CK signal at the beginning of the TAG reply. Then, the microcontroller needs to poll DOUT line to "find" the beginning of the TAG reply.
The decoding of the data from a TAG (manchester, NRZ, ...) needs to be done by the microcontroller as well as the protocol level (SOF, EOF, start bit, stop bit, CRC, ...). As the microcontroller controls the protocol level, it can easily recognize from SOF of ISO15693 and TAG-it protocols.
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Q:
Is it possible to read the registers of the MLX90121 in order to verify that the write succeeded?
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A:
The registers of the MLX90121 cannot be read back.
The fastest way to verify the write operation is to check the RF field which should be set ON after programming or to check the XBUF output if disabled in the registers settings.
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Q:
We recently acquired the MLX90121 chip. At the moment, the chip is interconnected with an MSP430 microcontroller. We are trying to send register data following the datasheet diagram. Nevertheless, even if the timing diagram seems respected, the registry settings are not always working. For Power-up, we respect a delay of 5ms, allowing the oscillator to be operational before trying to send data. Do you have an idea of what good be wrong ? Do you have any microcontroller program examples for programming these registries.
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A:
Please verify that all digital lines are set to the correct level (MODE = 0, RTB = 0). Please refer to the datasheet page 10. Please verify if the CK pulses (up and down) are of at least 500ns.
A firmware example is provided with the DVK90121.
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A:
The read range of the MLX90121 is much shorter than 1 meter. Even using the 1 watt power booster (see application note on melexis.com) the read range of over 1 meter cannot be obtained.
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Q:
Can anyone recommend to me a tag that can be used for MLX90121 that can be read at range greater than 1 meter. Please also advise to me where can I buy such tag.
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Q:
Is there any documentation on the TEST_ANA pin (pin 18) of the MLX90121? Is there any way to use it as an Received Signal Strength Indicator (RSSI)? Couterintuitively, it appears to follow DSYNC during Majority Voiting with ISO15693-Dual Sub-carrier. Note that while pin 18 is "RES3" on the MLX90121 datasheet, it is "TEST_ANA" on the EVB90121 schematic.
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A:
there is no documentation on the pin 18 (RES3). For proper function of the MLX90121, this pin should remain unconnected in the application.
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Q:
we want to use the 90121 in a data logger application, where the logger comunicates over RFID with a PC.
The data logger consists of a microcontroller a temperature sensor and an EEPROM where the measured data will be stored. The logger is battery driven and should run from a battery at least two years. When put into an interface, the content of the EEPROM should be transferred to a PC over RFID by using two 90121 (one in the logger and one in the PC-interface) The distence between the two antennas can be very short (< 1cm). Due to the fact that the logger is battery driven and the antenna distenca is very short, the power consumption of the 90121 in the logger should be as low as possible (<2mA).
Is there a way to achieve such low current consumption when transmitting data with the 90121?
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A:
The power consumption of the MLX90121 in the logger represents the average consumption according to the following points:
1) Power consumption of the RFID communication.
2) Power consumption of the RFID reception.
3) Power consumption in power down mode (no communication).
To reduce this average consumption, I only see to solutions.
The first one consists in reducing the emitted power during the communication. This is feasible because the reading distance should not be an issue. For that, please refer to the following application note available on our WEB-site "a low power reader based on the MLX90121".
The second one consists, if it is possible, in increasing the time between two RFID communications.
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Q:
I noticed that the reading distance tests were done using an ISO 15693 FSK / double sub carrier tag. Would this power reduction scheme work with an ISO 14443A tag?
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A:
It will until there is no power drop or turn offs inside a sequence. I will give an example.
If you power the system, then make the complete inventory anticollision sequence for all transponders, there should be no problem. But if you start inventory anticollision sequence and then turn field OFF, you will not be able to continue THIS sequence and will need to RESTART everything from the beginning.
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Q:
It is obvious from the Power Efficiency numbers in Table 1 that an appreciable amount of power is being lost in the series pass element Q1. Wouldn’t it be more efficient to simply power the RF output transistor with a lower voltage from a switching regulator? What is the lower limit of the voltage on the TX pin?
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A:
2) It will be more efficient, of course, but more complex.
In power-sensitive systems you can improve the performance better not by reducing or limiting current/voltage on the antenna, but by keeping power in the antenna OFF all the time and to only turn it ON when you need to perform an operation. Then to turn it OFF again. This can be done by the SW.
In fact it is not so easy to estimate the voltage limit on TX pin. This can be different depending on antenna and matching you use. This will also influence the reception part. If in your case it is sufficient to make a transponder operation in a short time and keep field OFF all other time, this way will be more preferable. Just try to make SW as fast as possible.
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A:
I am looking for the datasheet for the MLX90127.
Also I need to purchase the following part number for my sample design.
MLX90109 - I can buy this online
MLX90124 - I can not buy this online
MLX90125 - I can buy this online,
I noted that the MLX90124 is the transponder, which I need to make it work with MLX90109 & MLX 90125.
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A:
Thanks for your interest in our products. The MLX90124 and the MLX90127 were both discontinued last year..
You can indeed buy on line both the MLX90109 and the MLX90125. But I would recommend you buy the development kit DVK90109 which comes which suitable tags for the MLX90109.
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Q:
Dear Patrick,
Thanks for the respond.
my current task is to make, RFID Reader, for which I need to supply with tag, I need the following inventory:-
50 x Base Station, MLX90109+MLX90125
100 x Read Only Tag - MLX90??? (factory programed ID)
I am planing to purchase the DVK90109 kit, BUT before that I need to make sure I can get the tag's for Melexis of any other supplier.
In this matter, I hope you can recomandand sutiable Read Only Tag for my project.
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A:
For the sourcing of the 50 MLX90109+MLX90125, there is no problem. You can order them at Melexis.
For the tags, they can be sourced at companies like Sokymat (www.sokymat.com). We can help to establish the communication if needed.
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A:
From Sokymat, you can buy tags which support one of the following standards : Unique ID, Hitag 1, 2 and S. They will work with the MLX90109.
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A:
Mr.Ting, have updated me on this too. I will arrange to get 50 unit of the MLX90109+MLX90125 for melexis,
as for the tag, I visited the www.sokymat.com, they have various type of the tag, could you please advice me which tag(s) will work with 90109+90125
I also will arrange the DVK90109, to speed-up my development.
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A:
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Q:
We want to detect different RFID tags at different locations
using multiple antennas serially multiplexed to an m90121
reader IC. We currently using special 4066 analog switches
with an "low on" resistance and adjust the performance
using serially capacitors 47-222pF. It works, but the
"Performance" is in the most cases only medium.
We will also evaluate pico-gates
with an even lower resistance in the future. Is there an
another cheap way/idea to multiplex different antennas
to one m90121 reader IC? Or have you some suggestions
to improve our current solution.
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A:
we never try such a an antenna switching system like you describe. For me, it could be interesting to understand what is the cause of the performance loss. May be a first step will be to disconnect all antenna's but one, and short circuit the switch. If performances are not good at this stage, you should check the matching network. If performances are good, then you could remove the short circuit and check one antenna plus swicth. If performances are poor, this would mean that the switch you choose is not suitable. Otherwise, you could add the antenna plus switch one by one. Then you could understand better where to invest to get better performances.
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Q:
We are designing the reader for ISO15693 protocol with the IC MLX90121 and we required a range of 1 meter. So i wanted to ask that is this possible to get the range of 1 meter. We have got success in achieving the range of 25 cm but this range is with out external amplifier, only with 200mWatt. When we are using the external amplifier (as mentioned in your document) we are getting the out put power of 1 WATT but the return path is not working properly. Now we are not able to increase the range. so please sir if there is any optimize solution for this return path than reply to us. I also wanted to know that what is the maximun range we get with the 1 watt power, and with which antenna(size specification), can we drive an antenna of the 1meter by 1meter size as per our applications. Please reply us as soon as possible.............
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A:
With a 1Watt power booster and a rectangular antenna of 30x15cm we got about 45cm of reading distance using the ISO15693 FSK standard.
Getting up to 1meter will be very hard and a very large antenna as well as a bigger output power must be used. Unfortunately, we don't have such a specification to provide to you at that time.
About the return path of the 1Watt power booster, can you send me more information about the problem that you encountered?
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Q:
When we have tested the amplifier & return path we have faced the following problem.
1) As the voltage levels mentioned in your cookbook at tp2 and tp3 are 60 and 70 Vp-p,but we are getting 55 and 64 Vp-p respectively in the amplifier section.
2) There are two return path ckt. in your cookbook, one is of the simple resister network & other is the a diode detector. We have tried with both the ckt., with the first one (resistive network) we got the range of only 10 cm. Now without external amplifier we are able to get the range of 20 cm and with amplifier and return path we are getting the arang of 10 cm then what is use of using amplifier and return path. Whwn we have tried with second return path (diode detector) we were not able to detect the tag at any point, the tag was just not replying or may be its reply wuold not be detected. so this was the problem with return path.
3) If we are able to design an amplifier of 4 watt then can we use MLX90121 to drive a large antenna (size 145 cm x 75 cm), and what will be the better option for return path resistive network or diode detector.
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A:
1) The power loss on TP2 and TP3 can be due to the inductances L3, L4 and L5 used. Some SMD components have relatively small quality factor (about 20 @ 7MHz) which will reduce the power efficiency of the 1Watt booster. The best will be to use the through hole types from Farnell .
2) The small operating distance can be due to the power loss. Please first try to do the improvement as mentioned above.
3) At that time, we are only able to provide a solution for a 1Watt power booster.
The first method of return path using a resistive network will not provide the best improvements as it reduces the incoming RF field and also the back-modulation from the transponder. The best way will to use the external diode detector as implemented in the application note.
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Q:
We are testing the power amplifier circuit given in your application notes named as ”A power booster for the MLX90121”(Figure1).We have faced the problem in connection of source of IRFD110 to the mod (pin3) of RF chip.
As soon as we make this connection the current drawn is very high and the RF chip gets damaged. We wanted to understand the significance of connecting the source to the RFchip to the MOD along with RMOD resistor.
The document says that the MOD pin is used to judge the modulation depth but without connecting the MOD pin to the source of FET we are getting good modulation but the current is blocking our way to move further with the project.
Even if we considered the high current, the voltages at the output are not perfect(only 5 volts at the antenna{150cm X 75cm}) and at the TP3, voltages are upto the mark(65 volts).
Request for assistance in understanding the above situation.
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A:
The MOD connection is used to manage the 10% of modulation depth (external resistor Rmod). In this mode, the internal transistor will be set ON/OFF and modulate the RF field.
The low output power seems to be a matching problem. You can connect to the power booster output a 50-ohms load and tune the matching circuit (C4) to get the maximum output power. Then connect you antenna to verify that it is correctly adjusted.
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Q:
We are having the requirement of implementing 18000-3 mode 2 protocol. So if any of your product is supporting this protocol than please inform us. Also tell us if you are planning to launch a product in future supporting this protocol, if you are not having such product than please suggest us any other vendor
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Q:
we are working on the Universal Development board DVKRFID and with Evaluation board EVB90121
i am not getting consistent response for any of the sample cards. Is the chip compatible with ATMEL Crypto RF cards.The cards(14443 A/B, 15693) respond once after many consecutive requests(REQA,REQB and Inventory)
pls let me know the reason.
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A:
The DVK90121 provides a set of commands compliant with the standards ISO15693 and ISO14443. The crypto level is not supported by the DVK90121.
The communication with the computer seems to be good as the samples reply once after many consecutive requests.
Please verify the SMA connection.
Do you try to adjust the capacitor CV1? Please be sure that you get the maximum voltage amplitude on ANT (about 10Vpp).
Please insure that the RFID antenna is not close to a metallic object. The metallic environment must be avoided to get maximal performances.
Please try to change the two power supplies with ones from laboratory (7.5V DC). To verify if the power supplies provided with the kit disturb the EVB90121.
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Q:
we have tuned the CV1 Capacitor.but still we are not getting the consistent response.i am sending you the sample output.but factory setting will be giving somewhat good result.
<- TAG Resp 50920005F700000000007171854C 0000000000000000000000000000 CRC OK
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG Resp 50920005F700000000007171854C 0000000000000000000000000000 CRC OK
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG Resp 50920005F700000000007171854C 0000000000000000000000000000 CRC OK
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
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A:
Please verify if the register's settings in ISO14443B is according to the following:
7301000F00FF00000000033F00.
If not, please re-configure the MLX90121 registers accordingly and try if it works better.
Please verify if the power supply switch (J3) is on 3 or 5Volts. Please put it on 5V and try if it works better.
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Q:
we have tested with Power supply 5 volts only. and register set is same as u told.but still we are not getting the consistent result.
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Q:
this is the sample response .
<- TAG NoResp
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG Resp 50920005F700000000007171854C 0000000000000000000000000000 CRC OK
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG Resp 50920005F700000000007171854C 0000000000000000000000000000 CRC OK
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
Iso14b 050002 crc ->
<- OK - Command has been sent
<- TAG NoResp
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A:
We think your kit may not be functioning properly. A new kit has been sent to you for replacement.
Sorry for the inconvenience.
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Q:
We have suceeded in making an amplifier giving a output power of 1 Watt from your document ckt(12 volts).But the return given in the same documents is not working properly.So,can you suggest anyother return path circuit for getting the better range at 1.5 Watt and even at higher watts than that(5 to 8 Watts).
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A:
The time constant of the external detector can be a bit reduced by changing the resistor R2 from 22k to 12k.
At that time, we never implemented a power booster higher than 1.6Watt as describes in the power booster application note and we don’t have a complete solution to provide to you. But, the main problem with higher power is the saturation of the diode detector due to the high carrier amplitude and the relatively small amplitude of the back modulated signal. Therefore, a simple solution should be to add several diodes in series before D1, to reduce the carrier amplitude and to avoid the saturation of the diode detector.
Moreover, using several diodes will not reduce the back modulated signal and the ration data/carrier will increase.
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Q:
I am using the Iso14BSend function to send a command to the inside card which works with the ISO14443B-2. Should it work, or this command is only for ISO14443B-3?
I can see that there is one reply, but I cannot read it.
I need to buy smartcards of the ISO 14443B that works with the DVK90121, can I get from Melexis?
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A:
The function "Iso14BSend" provided with our example libraries can be used for ISO14443B communication -3 and -4. It encodes the Data to be sent according to the framing defined by the protocol (SOF, EOF, Start bits, Stop bits and CRC). The Data to be sent have to be specified by the user according to the protocol.
Best Regards
Denis
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Q:
is it possible to get an example of reading the UID of a VICC?
I am trying to read the UID with an MLX90121 and a Pic-Microcontroller.
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A:
You can get UID of a VICC by sending the ISO15693 inventory command.
Source code (in C language) for ISO15693 inventory are available in the development kit of the MLX90121 (DVK90121).Sources are for Atmega microcontroller but can easily modify them to use with a PIC
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