Read NDEF after tag write

RE: Read NDEF after tag write

pctj101 — Wed, 05 Jul 2017 17:00:52 GMT

Thanks also for posting the example code. I would have never found that I had to skip the first 2 bytes of the buffer.

RE: Read NDEF after tag write

Arepa — Tue, 23 May 2017 19:35:47 GMT

Thanks a lot :)

RE: Read NDEF after tag write

FormerMember — Tue, 23 May 2017 15:53:28 GMT

You would need to include nfc_ndef_msg_parser.c/.h and nfc_ndef_msg_parser_local.c/.h.

In addition, the NFC NDEF message parser module has to be enabled in sdk_config.h: (see the sdk_config.h file in this folder: \nRF5_SDK_13.0.0_04a0bfd\config )

// <e> NFC_NDEF_MSG_PARSER_ENABLED - nfc_ndef_msg_parser - NFC NDEF message parser module
//==========================================================
#ifndef NFC_NDEF_MSG_PARSER_ENABLED
#define NFC_NDEF_MSG_PARSER_ENABLED 0
#endif
#if  NFC_NDEF_MSG_PARSER_ENABLED
// <e> NFC_NDEF_MSG_PARSER_LOG_ENABLED - Enables logging in the module.
//==========================================================
#ifndef NFC_NDEF_MSG_PARSER_LOG_ENABLED
#define NFC_NDEF_MSG_PARSER_LOG_ENABLED 0
#endif
#if  NFC_NDEF_MSG_PARSER_LOG_ENABLED
// <o> NFC_NDEF_MSG_PARSER_LOG_LEVEL  - Default Severity level
 
// <0=> Off 
// <1=> Error 
// <2=> Warning 
// <3=> Info 
// <4=> Debug 

#ifndef NFC_NDEF_MSG_PARSER_LOG_LEVEL
#define NFC_NDEF_MSG_PARSER_LOG_LEVEL 3
#endif

// <o> NFC_NDEF_MSG_PARSER_INFO_COLOR  - ANSI escape code prefix.
 
// <0=> Default 
// <1=> Black 
// <2=> Red 
// <3=> Green 
// <4=> Yellow 
// <5=> Blue 
// <6=> Magenta 
// <7=> Cyan 
// <8=> White 

#ifndef NFC_NDEF_MSG_PARSER_INFO_COLOR
#define NFC_NDEF_MSG_PARSER_INFO_COLOR 0
#endif

#endif //NFC_NDEF_MSG_PARSER_LOG_ENABLED
// </e>

#endif //NFC_NDEF_MSG_PARSER_ENABLED
// </e>

RE: Read NDEF after tag write

Arepa — Tue, 23 May 2017 15:18:52 GMT

Hi Kristin, what includes are necessaries to be able to use the functions NFC_NDEF_PARSER_REQIRED_MEMO_SIZE_CALC and ndef_msg_printout?

Thanks

RE: Read NDEF after tag write

FormerMember — Thu, 20 Apr 2017 11:45:21 GMT

I don't know what your code looks like, so I will just tell how it works.

When writing to the NFC tag from another device, the initial data will be over written, and stored in the set buffer in nfc_t4t_ndef_rwpayload_set() during the initialization. In the example writable_ndef_msg, the buffer is m_ndef_msg_buf.

Since m_ndef_msg_buf is overwritten upon a write, that is where the data to be parsed is located. (Note: the data field in the event "NFC_T4T_EVENT_NDEF_UPDATED" doesn't contain valid data. The only valid data for that event is dataLength.)

For a Tag Type 4, the written data can be printed out the following way:

/**
* @brief Callback function for handling NFC events.
*/
static void nfc_callback(void          * context,
                     nfc_t4t_event_t event,
                     const uint8_t * data,
                     size_t          dataLength,
                     uint32_t        flags)
{
    (void)context;
	ret_code_t ret_val;

    uint8_t  read_nfc_buffer[NFC_NDEF_PARSER_REQIRED_MEMO_SIZE_CALC(10)];
    uint32_t read_nfc_buffer_length = sizeof(read_nfc_buffer);		

    switch (event)
    {
        ....

        case NFC_T4T_EVENT_NDEF_UPDATED:
				
			NRF_LOG_INFO("NFC_T4T_EVENT_NDEF_UPDATED \r\n");
		
            if (dataLength == 0)
            {
                m_update_state = true;
	            NRF_LOG_INFO("DataLength:  0 \r\n");
            }
            else if (m_update_state == true)
            {
	            ret_val = ndef_msg_parser(read_nfc_buffer, &read_nfc_buffer_length, m_ndef_msg_buf+2, &dataLength);
		        //APP_ERROR_CHECK(ret_val);
			    if (ret_val != NRF_SUCCESS)
			    {
			        NRF_LOG_INFO("Error code: 0x%x \r\n", ret_val);
				    NRF_LOG_INFO("Error during parsing a NDEF message.\r\n");
			    }
			
			    ndef_msg_printout((nfc_ndef_msg_desc_t *) read_nfc_buffer);
                m_update_state = false;
                bsp_board_led_on(BSP_BOARD_LED_1);
            }
            break;

    default:
        break;
    }
}