ST25 NFC/RFID tags and readers

Hi,We have a project with ST25R3916B to read a NFC-B T4T card. This driver works fine.In the same state machine I am adding support for reading a NFC-A card. The `rfalNfcGetActiveDevice` correctly returns RFAL_NFC_LISTEN_TYPE_NFCA and rfalNfcaPollerCheckPresence returns RFAL_ERR_NONE, however rfalNfcaPollerFullCollisionResolution() function is returning a RFAL_ERR_TIMEOUT The Type 4B reader loop has the equivalent functions calls as the Type 4A reader and works fine, but Type 4A is having the abovementioned timeout issues with collision resolution.I am having some issues with attaching a .c file, so I will post the whole function in a comment after the question is published

Dear ST Support Team / Community Engineers,I am currently integrating the ST25DV04KC into my design. The VCC and LPD pins are connected to an MCU, which controls the transition between normal operation and ultra-low power mode.During testing, I observed an abnormal voltage behavior on the LPD pin:System Voltage: 3.1V Pull-up Resistor: 4.7kΩ (External) Issue: During the level switching transition, the LPD pin voltage stalls at an intermediate level of approximately 2.1V, instead of rising cleanly to VCC. This intermediate voltage persists long enough to potentially cause logic uncertainty for the MCU.Troubleshooting Steps Taken:Reduced Pull-up Resistance: I replaced the 4.7kΩ resistor with a 1.2kΩ resistor. This change successfully eliminated the intermediate voltage plateau, and the signal now transitions correctly. VCC Disconnection Test: I also noticed that disconnecting the VCC supply seems to eliminate this phenomenon as well.My Questions:What is the physical mechanism causing this

I am currently working with an ST25R300 reader IC and would like to increase the available RF power at the antenna in order to achieve a higher field strength/read range.I only need ISO/IEC 15693 modulation.I need about 5-8 watts of output power.Is it possible to drive a H bridge driver IC with the push pull output of the ST25R300? And what about deadtime etc.Are there any reference designs or application notes from ST showing an ST25R device combined with an external PA? Thank you in advance!

Hi, We are using PCB coil antenna. We need your support to tune the filter circuit.Thanks,Sankar.K

Hello, I have a problem after updating the system to Android 16. Before, everything was great. I have a custom application to work with ST25DV04KC. Now, the NFC service crashes before connection, and the system app opens NDEEF. Only on the first "tap," after turning NFC on/off, the connection is correct. Is there any workaround before they change it in Android? Thanks for any help.

Hi again,Since the new version of ST Community I can't find my previous post, so I'm creating a new topic to follow up on the old one. The replies from @AScha.3 and @Brian TIDAL on that thread helped me a lot before it disappeared.As I mentioned, I'm a beginner in this field. The full context is in my earlier post:I have just one more question. You mentioned that building an external antenna is easy, but is it really doable for a beginner? I'd like to know whether I can realistically do it myself if I buy the right equipment to measure inductance, or whether I need an expert to guide me.Also, in addition to AN6065, I found AN2866, which is more readable in my opinion and provides a step-by-step procedure. I don't understand everything yet, but I'll work through it.Thanks!

So our System works fine most of the time but sometimes the Reader does not detect the tag and we observe that rfalNfcState are just keep fluctuating between RFAL_NFC_STATE_POLL_TECHDETECT and  RFAL_NFC_STATE_LISTEN_TECHDETECT  same as when no tag present in the field of Reader and it is not able to satisfy this if condition.“if( rfalNfcIsDevActivated( rfalNfcGetState() ) ) // this if condition”We observed that even if we do controller reset it doesn’t fix the issue only when we power cycle the reader{st25r3911b} it start working again normally.I’m attaching the code with this i want your team to review it to let us know what exactly we are doing wrong which leading to this state where our rfal state machine not switching properly, With Restart_flag we are doing reinitialization i want you to review that whatever sequence we are following is correct or not  Main.c  {Rfid Reinitialization sequence}Please help us fix this issue and could you provide or help us that through software funct

Hi ,We observed the timing details for each state during card detection. These measurements were captured while running the demo cycle continuously in a while loop for card detection on bare metal. We are using the NFC Reader stack on an AUTOSAR platform and executing the NFC task every 1 ms. During testing with NFC-A and Proprietary technologies, we observed that the card detection and validation process takes approximately 300 ms.Could you help us understand how these timing values are expected to be observed and interpreted?We observed that the PollTechDetectCnt reached 1162 during testing. Could you please confirm the expected number of iterations for each state in the polling and card detection sequence? Initialization for discovery parameters -   discParam.compMode = RFAL_COMPLIANCE_MODE_NFC;  discParam.devLimit = 1U;  discParam.nfcfBR = RFAL_BR_212;  discParam.maxBR = RFAL_BR_KEEP;  discParam.p2pNfcaPrio = false;  discParam.wakeupEnabled = false;  discParam.wakeupConfigDefault =

This account only shares restored community content posted by members between May 22 and June 9, 2026, who did not register for the new community.Hello, i need help for an issue with HLTA command.I'm working with ST25R100 and I'm writing code direclty in uP without RFAL library. I finished writing anticollision routine and it works fine, but when I try to put PICC in HALT mode it continues to respond to REQA command.Because PICC comes from SELECT command, I think that registers settings are ok for HLTA command and I need to do no change about them. I take care not to turn off RF field so selected PICC does not return to IDLE state....Also, if I send a READ command to PICC instead of HLTA I can read all data without any problem. Any suggestion? Thank you

This account only shares restored community content posted by members between May 22 and June 9, 2026, who did not register for the new community.antenna tuning section pinout is correct or not  capacitor section im facing issue for developing A SMART RFID reader using ST25R3912-AQWT this chip as per the application circuit it was mentioned RFO1 AND RFO2 are trasmitter pins but what about the TO1 AND TO2 pins can you guide me for this  also keeping components inside the antenna is permitted or should i avoid it...?  

Hello ST Team,Could you please review the attached ST25DV60KC NFC antenna design and provide any recommendations regarding the antenna design, schematic, and PCB layout?Any comments or best practices before PCB release would be greatly appreciated.Thank you for your support.

Hi everyone,I’m currently working with the CR95HF evaluation kit and looking into using the provided DLL (CR95HF.dll) for PC-side communication for a legacy projectHowever, the DLL seems to be compatible with 32-bit systems and I am looking for the 64-bit compatible version. As clarified in other discussions, the DLL needs to be recompiled for x64 compatibility. (CR95HF DLL x64 compatibility – is a 64-bit version available? | Community)So my questions are:Is there now an official x64-compatible version of the CR95HF DLL available? Or is the recommended approach still to request/use the source code and rebuild the DLL for x64 systems?Regards,Aman

Help Needed: ST25R500 Antenna Matching and Unexpected Reading Distance ResultsHello everyone,Thank you for taking the time to read my post.I am currently using the ST25R500 and designing a reader with the goal of achieving the maximum possible reading distance. I have been working on the antenna design, impedance matching, and the internal transmitter impedance settings of the ST25R500, but I have encountered some confusing results and would really appreciate your advice.My antenna is a 2-turn enamelled-wire coil. For the impedance matching, I am using the impedance matching software officially recommended by ST.Based on the recommendations in the datasheet, I set my target impedance to:10 Ω − j4 ΩAs far as I understand, this target impedance should be within the recommended range.I entered my antenna parameters into the official matching software and used its built-in simulator. I then adjusted the values of the matching components, as shown in Figures 1 and 2.However, after actually

Setup Board: X-NUCLEO-NFC09A1 (ST25R100), brand new, unmodified, no jumpers/solder bridges changed Host: STM32, custom C++17 driver (register-level, not RFAL) SPI: confirmed working — bring-up sequence completes, all register reads/writes verified against DS14139 Rev 4 SymptomThe autonomous wake-up measurement cycle (triggered internally by the WUT every wut period) never emits any RF onto RFO1/RFO2, confirmed directly on an oscilloscope. However, the CALIBRATE_WU_MEASUREMENT direct command (0x74), issued manually once during bring-up, reliably emits a real RF burst every time (5 sub-pulses of ~26 µs each, ~130 µs total).This has been reproduced consistently across many test runs, with the following independently confirmed facts: wu_en is set and read back correctly (OPERATION = 0x01). The WU timer itself is confirmed running: with wuti (WU_CONTROL_1 bit 3) set, I_wut fires reliably in IRQ_STATUS_3 on schedule, tested at both wut = 77.3 ms and wut = 9.7 ms. IRQ_MASK_3 correctly

Hi, I have designed a board with a total antenna width of 10 mm and 7 turns, and a rectangular antenna.But it doesn’t read by smartphone (NFC-enabled) or Readers. Can you please help me with the problems? 

 Hello ST Team,I am currently working on a project using the ST25R3916B NFC reader, and I would like to study and reference the PCB design shown in Figure 6, “Device used for single ended antenna with cable,” of application note AN5592.Could you please provide the editable PCB project files for this reference design, such as the Altium schematic and PCB layout files?I have checked the application note and the ST website, but I could not find the corresponding PCB source files.Application note reference:https://www.st.com/resource/en/application_note/an5592-st25r-single-ended-antenna-matching-stmicroelectronics.pdfThank you very much for your support!

This is not a real question, this is just knowledge sharing… For the context, I would read first. At this point I had x86 NFC Tag Programming application, I have been waiting for the STM to release x64-bit version of the DLLs so I could update my application to x64.I have been lurking around the community and finally found but this did not help as with the release of v3.0.0, it did came with x64 bit of DLLs but I had real hard time integrating them into my project!! Quite disappointing, eh?!! I gave up the idea of updating my application to x64 until very recently I stumble upon another question based on the question title, I clicked on it with a lot of hope and what I found was quite disappointing. Basically I felt I was in a ditch where I could not update my application to x64 even though I have x64 bit DLLs!

Hello,I am designing an NFC reader based on the ST25R300, using the STEVAL-D25R300A schematic as a reference for the antenna matching network. My board uses the same component values on each side of the differential output:L1/L2 = 120 nH (EMC filter series)C11/C8 = 390 pF (EMC filter shunt)C1/C12 = 82 pF each, in parallel (series matching)C14 = 120 pF (shunt)C67 = 39 pF (shunt)C59 = 10 pF, C16 = 150 pF (RFI divider)R3/R4 = 2.2 ohmI could not find the antenna coil parameters in the user manual or the design files. Could you please provide the following for the antenna used on STEVAL-D25R300A?1. Coil inductance at 13.56 MHz2. Coil AC resistance (or Q) at 13.56 MHz3. Whether the antenna is a PCB trace coil or a discrete component, and if it is a PCB trace, the outer dimensions and number of turns4. The target differential impedance the matching network above was designed for Thank you.

Dear ST Support Team,We are currently developing a board based on the ST25DV04K and would appreciate your guidance regarding the antenna interface.In our schematic, we have placed a π coupling filter (series inductors and shunt capacitors) between the AC0/AC1 pins and the antenna matching circuit, upstream of the latter, for coupling at 13.56 MHz, as shown in the attached schematic.Could you please clarify whether the use of this π coupling filter, positioned before the matching circuit, is recommended by ST, or whether it is not necessary in this configuration?Thank you in advance for your support — we look forward to your recommendations.Best regards, 

Hi team,I am working on a firmware upgrade implementation using the ST25DV04KC NFC tag in FTM (Fast Transfer Mode).I have successfully ported the ST25FTM library to my target microcontroller. Basic commands and demos—such as checking the board version and sending passwords—work consistently.However, I am experiencing a severe reliability issue with the actual Firmware Upgrade process. The upgrade fails roughly 90% of the time. It only succeeds occasionally (~10% success rate). The target 8 Bit PIC18 microcontroller.I have attached the console log of a failed session below for reference. Could you please help me identify what might be causing these frequent failures, or let me know if you need any additional logs or hardware details from my side? Thanks.Console Logs:Jul 09, 2026 8:49:50 AM com.st.st25sdk.STLog i INFO: mState = PREPARE_PACKET Jul 09, 2026 8:49:50 AM com.st.st25sdk.STLog i INFO: sendNextPacket Jul 09, 2026 8:49:50 AM com.st.st25sdk.STLog i INFO: preparePacket Jul 09, 2026

Hi,We are using the ST25R3920B NFC reader IC along with the NXP S32K312 MCU running an AUTOSAR OS for NFC card detection.We have observed that, after the NFC wake-up event, the NFC initialization and polling sequence takes approximately 300 ms before a card is detected. This startup time is longer than expected and is impacting our application requirements.Could you please suggest any configuration changes, RFAL optimizations, or best practices to reduce the NFC initialization and polling time? If there are any recommended settings for use with an AUTOSAR-based system or the ST25R3920B that can help improve startup performance, we would greatly appreciate your guidance.Thanks,Anitha

Hello Team,I am facing RF read and write issues with the M24LR16E‑R EEPROM.The exact problem is as follows:When I take a new EEPROM and write data to it using an RF NFC reader for the first time, the operation is successful. However, during subsequent attempts to read and write: In some EEPROMs, RF read works but write fails but I2C read/Write working. In some devices, both read and write operations fail but I2C read/Write working. A few EEPROMs work correctly without any issues. In our application, we are using Sector 2 and Sector 3 for user data storage.When I read data from the problematic EEPROMs through St25 mobile application, I observe the following:Sector 0 and Sector 1 Security Status is 0x00. And the data read and write is working in these 2 sectors. Sector 2 to Sector 15 Security status: Current Security Status: 0x09 New Security Status: 0x09 Additionally, I receive the warning:“Sector locked. Security Status can only be changed through I2C.”I am not sure why the security

Hello, I currently using the STM32F401RCT and the ST25R100-CMET.Its a battery powered device and want to put the ST25 chip in sleep. in rfal_nfc.c I found rfalNfcDeactivate for disabling, but I don’t get it enabled.//Power saving functionsvoid NFC_Enable(void){ printf("Enabling NFC chip\r\n"); rfalNfcInitialize(); rfalNfcDiscover(&discParamNfc);}void NFC_Disable(void){ printf("Disabling NFC chip\r\n"); rfalNfcDeactivate(RFAL_NFC_DEACTIVATE_IDLE);}Right now when I enable the chip it doesn’t detect tags. It does work and detect tags without the power saving functions.I have been reading through this file: RF/NFC abstraction layer (RFAL) - User manual But haven’t found a solution.Have I missed anything?Kind regards, William  

I’m designing a tag coil for the ST25DV-04k. I am planning to use the ST25 to harvest NFC energy from a phone tap for a bioimpedance sensor (MAX30002). The ST25DV will then relay the sensor measurement to the phone via NFC again. I used an online calculator to design the tag coil, and these were the parameters I chose. Parameters for tag coilHowever, I am unsure if my quality factor is too high. “59.77” is before coupling, and I assume it will be lower after that. I understand that a high Q is great for energy harvesting, but it can limit the bandwidth and garble communication between the tag and the reader.Is my Q too high right now? If so, what is the optimal Q factor range? Anything else that stands out from my coil design?

Hello,I am using the ST25R200 evaluation board with the STSW-ST25R020 firmware package.I am planning to develop a custom Python GUI that displays a specific text string whenever an NFC tag is detected by the board. To achieve this, I want to modify the C firmware so it actively streams out a text string via UART/VCP as soon as a tag enters the field.Could you please guide me on the following?Which specific source file and function in the STSW-ST25R020 package handle the successful tag detection/inventory loop where the tag's UID is retrieved? Where is the best place to insert a custom printf or logging function to stream this text data out via UART immediately upon detection? Thank you very much for your help!