Reporting 2 bugs on the X-CUBE-NFC5 rfalST25xVPollerWriteMessage API

[Gustavo.Laureano]

Hi,

I would like to report 2 possible bugs on the rfalST25xVPollerWriteMessage implementation:

1. The msgLen parameter must be "number of Data bytes minus 1", as a direct translation from the "Write message" command, but msgLen == 0 is not accepted as valid (rfal_st25xv.c line 205), failing to write 1 byte-long messages, which according to the ST25DV datasheet should be OK.
2. The required TX buffer len (calculated on line 202, and checked on line 205), considers 2 bytes for the msgLen parameter, but this parameter is only 1 byte long, preventing from using buffers that are the exact (and correct) number of bytes long.

Best Regards

Gustavo

[Brian TIDAL]

Hi,

which version of RFAL do you use (see #define RFAL_VERSION  in rfal_rf.h)?

Issue #1 has been corrected and the fix is provided in latest RFAL versions. The updated code in line 205 is the following:

/* Check for valid parameters */
 if( (txBuf == NULL) || (msgData == NULL) || (txBufLen < msgIt) )
 {
 return ERR_PARAM;
 }

Regarding the second issue you reported, here is the format of the Write Message:

 Thus, the size of the buffer is the sum of:

• sizeof(flags): 1 byte
• sizeof(cmd): 1 byte
• sizeof(ICMfgCode): 1 byte
• [sizeof(UID: 8 bytes] optional
• sizeof(MSGLen): 1 byte
• MSGLen + 1

Therefore , if I am not wrong, line 202 is correct:

/* Calculate required Tx buf length: Mfg Code UID MSGLen MSGLen+1 */
 msgIt = (uint16_t)( msgLen + sizeof(flags) + sizeof(cmd) + 1U + ((uid != NULL) ? RFAL_NFCV_UID_LEN : 0U) + 1U + 1U );

Note: the MSGLen parameter has been clarified in the comments:

/* Note: MSGlength parameter of the command is the number of Data bytes minus - 1 (00 for 1 byte of data, FFh for 256 bytes of data) */

One additional information, the ST25 Embedded NFC library provides a ST25 fast transfer mode embedded library. See Application Note AN5512 and related ST25NFC_Embedded_Lib_ST25R3916\Projects\STM32L476RG-Nucleo\Applications\X-NUCLEO-NFC06A1\FTM demo.

Rgds

BT

[Gustavo.Laureano]

Hi @Brian TIDAL_O​ , thanks for the fast reply!

#1 I am using v2.0.10, just checked and this is the latest one available on https://www.st.com/en/embedded-software/x-cube-nfc5.html

Where can I find this updated version of the NFC5 RFAL?

#2 You are right, the last +1 is the correct offset for msgLen when considering its value is "number of Data bytes minus 1", my bad!

#3 Didnt know about this lib, I will take a look, thanks!

[Brian TIDAL]

Hi,

updated versions of the RFAL are available either in  the ST25 Embedded NFC library with several new demos or as a standalone version in RFAL for ST25R3911B. I would recommend the ST25 Embedded NFC library as it comes with demos.

Rgds

BT