MLX90121 Frequently asked Questions

RFID

Question
Hello sir, I am working on 13.56 Mhz RFID (MLX90121) project. I am little bit confuse on using symbol transmission method. T CK and Din lines are used to transmit the symbols, but I still not clear about the following: 1. Is that the width of the CK pulse be concerned? 2. Does the microcontroller need to provide the addresses of the symbols to be transmitted ? 3. Does the microcontroller send any neccessary signal through Din line during the transmission time(request)? 4. To transmit sym0, does the microcontroller need to send any pulse clock? 5. According to the MLX90121 data sheet(Mar/04), page 13 of 25, the three start bits are used to transmit sym0 to sym6. I really confuse because sym1, sym2 and sym4 all have one CK pulse what make the hardware encode the right symbol to transmit? is that the address involved to encode this symbols?

Question
I am recently using the 13.56 MHs RFID Transceiver, MLX90121 for my project. I went through the datasheet but did not see the internal SPI port. Is that ok if I interface with the SPI of the microcontroller? Please ive me an advice what how can interface with the AVR microcontroller !

Answer
The MLX90121 doesn't feature a SPI port. The interface is proprietary in order to allow for real time data transfer. In principle, this interface is clearly described in the datahseet. It has a 3 wire interface than can be hooked at any of the I/O ports of an ATMEL.

RFID project help

Answer
I will try to answer to all yours questions: Melexis has two RFID transceiver ICs available: the MLX90109 (125kHz) and the MLX90121 (13.56MHz). The selection between the two depends on your system requirements (reading distance, size of the antennae, ...) Both of them can be driven by the 68HC12. Please note also that Melexis doesn't offer standard transponder ICs any longer. This is why you couldn't find on our WEB site obsolete references such as MLX90108, MLX90110 and MLX90111. Our DVK boards are built according to the system you described TAG <-> Reader (beased on either 90109 or 90121) <-> PC. So, it shouldn't be any problem to develop the application you described. Please note that the reading distance of the MLX90109 will not exceed a couple of centimers, unless you use very large antennae.

Tags for MLX90121

Answer
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.

Question
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.

Multiple Tags

Answer
Anti-colllision has to do with the protocol. It should be implemented inside the microcontroller which controls the MLX90121 transceiver.

mlx90121 - config register

Answer
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.

Answer
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

Question
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 ?

Antenna for MLX90121

Question
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.

Reading range for MLX90121

Answer
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

MLX90121 antenna circuit example needed

Question
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?

Help about MLX90121

Question
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

frequency range for MLX90121

Answer
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.

90121 inv

Answer
which would be the command for inventory (uid) of tag, using mlx90121 and tag by texas?

Answer
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?

Firmware ATMega128 in DVK90121

Question
We have been working with RFID at 13.56Mhz for 3 years and we think MLX90121 is a very interesting product. We are now starting a new electronic RFID reader development probably with your chip. We are getting samples and DVK90121 but in order to simplify the development we would like to know if it is possible to get the firmware of the ATMega128 microcontroller of DVK90121 board. We use usually this microcontroller and your help would be grateful for our purposes.

MLX90121 - ultra low power application

Answer
The feature you are looking for is called "tag detection". We had some idea to implement it with the MLX90121.

EVB90109 & EVB90121 boards

Answer
Maybe the registers settings of the MLX90121 is not correct. Can you please send me the registers configuration that you have for every modes (ISO15693 ASK and FSK, ISO14443 A and B)? You will see the registers settings if you click on the "R" button on the top of the UT121 software (this is explain in the DVK90121 user manual).

MLX90121 Reading Configuration Registers

Question
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?

Answer
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.

MLX90121 Ultra Low Power

Answer
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.

ISO14443A Read /Write Range

Question
i am using mlx90121 for development ISO Standard reader for Melexis antenna 12cm.x12cm. how many range for read/write Mifare ISO14443A?

c210 tags w/mlx90121

Question
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?

ISO15693 reader using MLX90121

Question
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).

Answer
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).

MLX90109 & MLX90121 Choose

Question
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?

Answer
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.

Question
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.

Reception with MLX90121

Question
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?

Answer
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.

Question
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.

Answer
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.

Answer
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.

Answer
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.

MLX90121 collision detection

Question
How does the MLX901212 detect a collision?

Answer
The MLX90121 is unable to detect a collision y itself. The anticollision procedure has to be handled by the software.

MLX90121 input capacitance

Question
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?

About MLX90121 questions

Question
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?

Answer
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.

13.56MHz RFID system

Answer
The MLX90121 is designed to provide 250mWatt to a 50-ohms load. This is less than the maximum magnetic field of 7.5 A/m specified by the ISO standard. A power booster version with an external transistor can be implemented. The MLX90121 is independant to the type of modulation used (Manchester, Biphase, NRZ). The external microcontroller will do the decoding. The ISO standards ISO14443 and ISO15693 use a sub-carrier encoded in ASK, FSK or PSK. The data stream level can be encoded in Manchester (ISO15693 and ISO14443 A) or NRZ (ISO14443B). For more information, please refer to the related documentation of these standards.

increasing the range of the reader

Question
we are using the MLX90121 chip for the rf section in our reader and we have also implemented the amplifier ckt using IRFD110, but as mention in the document of that amplifier it just gives the output power of 1 WATT, but we required the output power of 4 WATT, so please can you suggest us any changes for increasing the output power.

Answer
you should try to use an external detector. there are some app. notes from st micro. by the way we have just done a design with the MLX90121 it works fine

Question
I have searched with the st. micro. but was not able find any optimize solution, actually we wnted to run a antenna of 1M by 1M giving the range of the of one metre. we have designed a reader with MLX90121 but its output power is not sufficient to run such antenna so then we have designed the amplifier which is capable to giving power to some extend, but the main problen is with the return path. so can i get any of the link supporting such problems or any optimize solution for the return path.

DVK90121 NFC

Answer
The DVK90121 allows you communicate with a transponder using basic ISO commands (ISO15693 and ISO14443). The NFC protocol at 212kbit/s as presented in the corresponding application note is not supported by the development kit. For that, you will need to write the firmware by yourself. Please note that only the NFC at 212kbit/s (Felica protocol) is supported by the MLX90121. The others modes (106kbit/s, 424kbit/s and 848kbit/s) will not be able to implemented with this device.

amplifier circuit for 2Watt

Question
We have implemented the amplifier circuit given in your application note “A Power Booster for the MLX90121” (Page no 1 of 9).We have implemented the whole circuit with the RF chip and microcontroller which gets the supply from the USB. With the source of IRFD110 connected to the mod pin (pin 3 of RF chip),we performed different testing, but the required output is not achieved and faced the loading problem. Case 1: We have taken 12 volt supply from the regulated dc power supply and 5 volt internally from the board means from USB itself. Since the ground of both the different supply is same, We faced the loading problem, which means we were not able to give the supply voltage upto 12 volt, but could only reach upto 7 volt…hence the output voltages are not to the mark. Case 2: We have taken 12 volt supply from the regulated dc power supply and 5 volt externally from the 7805. but as soon as we connect the 5 volt supply point of the amplifier to the 7805, the voltages at that pin are reduced to 2 volt dc with some ac voltage…hence the output voltages are very less.

Answer
To avoid this problem, a solution should be to use the +12Volts power supply which, is already needed for the power booster, to generate the +5Volts required by the MLX90121. Then both supplies will have the same reference. If the circuit really needs to be supplied from the USB, a solution should be to use another power booster which required only one supply voltage (+5Volts). For this, please refer to our application note "A +5Volts power booster for the MLX90121" available on our WEB site.

MLX90121 parameter

Question
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 ?

Answer
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.

MLX 90121 - Base band communication

Answer
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.

Question
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

Answer
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

power amplifier and modulation

Question
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.

MLX90121 Registers configuration

Question
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.

MLX90121 - Inductors and capacitors

Question
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)?

MLX90121 - Direct Modulation

Question
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?

Answer
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).

MLX-90121 - Control lines from microcontroller

Question
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.

Answer
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.

MLX90121 - Operating temperature range of application circuit plus power amp

Question
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.

Answer
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.

MLX90121 Entering PowerState Down

Answer
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.

MLX90121 - Different voltages?

Question
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

Answer
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

Maximum output with MLX90121

Details MLX90121 output stage for Pspice

Question
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.

Answer
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.

optimize solution for the long range

Question
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.............

Question
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.

i need source code for DVK90121

Answer
The firmware of our development kit DVK90121 can be delivered on demand using the user interface software UT121. Please note that this firmware is delivered as an example only and therefore, we will not provide any support on it. Moreover, we cannot guarantee that this software will fit in your application and will be plug and play. You will need to write the firmware of the MLX90121 according to your application. Please contact us through your local sales representative.

Question
I recently purchased four DVK90121 and I can see the source code using the UT121 software that came with the CD. But, I cannot copy the code to my workspace. I want to test some features especially the "Direct Transmission/Reception" by modifying the MLX90121 registers. Please let me know how I can get access to the C language code. I have the necessary JTAG and other dev platform for Atmega 128.

Response from sample cards in not consistant(mlx90121)

Answer
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.

MLX90121 13.56MHz RFID Transceiver

Question
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?

Answer
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.

Question
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?

Answer
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.

EVB90121 - wrong signals on Dout

Question
I´ve got the Evaluation Board for the MLX90121(EVB90121) and use it to send power to my custom-built sensor-tag circuit and to recieve the data. The senor-tag modulates the field by ASK with a subcarrier (423kHz). I run the EVB in direct reception mode. Now the problem... On the Dout line are some "peaks" appearing without having any modulation on the 13,56MHz field. And the sensor-tag is out of range. The "peaks" are comming more or less periodical. I´ve tried to shield the antenna. Without any result. Disconnecting the antenna doesn´t show any effect either.

1W RFID power booster

Answer
The role of the three resistors attenuator is to reduce the amplitude of the 13.56MHz carrier at the input of the MLX90121 to be correctly decoded. But, as a side effect, it also reduces the amplitude of the transponder's load modulation. Therefore, better results will be achieved with an external diode detector as implemented in the corresponding application note. You should not get 10Vpp Vpp of useful signal (load modulation + rest of 13.56MHz) at the output of the external detector. The spikes of the command sent by the reader can be quite high but it is not important as it will not be decoded anymore. I already made the test with 26Vpp of 13.56MHz carrier and I get 2.2-2.4Vpp of useful signal with correct decoding. Can you check the implementation of the external detector? Do you correctly adjust R2 and C2 (22k, 100pF) which fix the time constant of the decoder? Do you place the resistor R3 which insure a correct biasing of the MLX90121? What is the register’s configuration used?

Answer
Dear, As the command is sent using 100% of modulation depth, I think the response is compliant with the protocol ISO14443-A. 1: Yes, red arrow is not at the correct place. 2: 2.2-2.4Volts is the useful signal, corresponding to the residual 13.56MHz with the load modulation. The DC level at the Rx pin is set by the pull-up resistor R3 which is connected on the +5Volts power supply. 3: C3 cuts the high DC level due to the big amplitude of the 13.56MHz (about 10V) while R3 insures a correct biasing of the MLX90121 and therefore adjust the DC level at the Rx pin. Its value has been set to 27Kohm and must not be changed. 4: Not needed. 5: The command is ignored by the firmware which knows when it sends command to the transponder.After sending information, the firmware has to synchronize the MLX90121 on the transponder's response (asserting CK high at the beginning of the transponder's response). For more information, please refer to the application note "MLX90121: Communication with ISO standards" available on our WEB-site.

build 2007/02/02

Answer
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.

Question
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.

MLX90121 power booster

Question
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?

read MLX90121 registers

Question
Is it possible to read the registers of the MLX90121 in order to verify that the write succeeded?

Answer
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.

MLX90121 TEST_ANA pin

Question
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.

Answer
there is no documentation on the pin 18 (RES3). For proper function of the MLX90121, this pin should remain unconnected in the application.

MLX90121 @ 250 kHz Subcarrier?

Question
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)?

Answer
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).

Spikes on DOUT

Answer
This problem depends on the protocol used. ISO15693 single subcarrier: DOUT must be stable and should not switch. If it does, you should try to modify the level of the comparator. If it doesn't help, contact us. ISO14443A: DOUT must be stable and should not switch. If it does, you should try to modify the level of the comparator. If it doesn't help, contact us. ISO14443B: For this protocol, MLX90121 require the use of a different internal decoder. In this case, SW filtering is necessary. In order to help you, a software library is available in our development kit DVK90121. You will find example of implementation for all previously mentioned protocol. You will find more information on the document FW90121: "firmware for MLX90121 based reader" The DVK90121 is available through our sales channel: www.melexis.com/contact.asp

MLX90121 NFC

Question
Is there any reference design of letting 2 MLX90121 talk to each other?

Answer
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.

General quesions for DVK90121

Question
Can you advise me on how to start using the development kit DVK90121? How does this development kit actually function? Is it to configure the MLX90121?

Answer
DVK90121 is a kit which allows you to test the entire features of the MLX90121 and start to design your own application. Through the user interface UT121 you can configure the MLX90121 and communicate with your tag by sending command. The provided RFID library (C code) allows you to have your own application running together with the microcontroller.

MLX90121 configuration

Question
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?

MLX90121

Question
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?

Question
Im wondering if it is possible to achieve a range of 4m from MlX90121 with a 1 watt 5 volt power booster

Question
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

Answer
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

Question
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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