To program a tag, use the precompiled Type 2 Tag library.

Complete the following steps:

1. Implement a callback function that handles events from the Type 2 Tag library and register it:

   
             uint32_t  err_code;
            
   
            
   
             
              /* Callback for NFC events */
             
            
   
             
              static
             
             
              void
             
             nfc_callback(
             
              void
             
             * context,
             
              nfc_t2t_event_t
             
             event,
             
              const
             
             uint8_t * p_data,
             
              size_t
             
             data_length)
            
   
             {
            
   
             ...
            
   
             }
            
   
            
   
             
              /* Set up NFC and register application callback for NFC events. */
             
            
   
             err_code =
             
              nfc_t2t_setup
             
             (nfc_callback, NULL);
            
   
             
              APP_ERROR_CHECK
             
             (err_code);
            

   The NFCT interrupt handler runs at priority level APP_LOW.
   
   
2. Configure the data for the tag. You can provide the data as NDEF message (recommended, see NFC Data Exchange Format ) or as a raw TLV structure (advanced usage, see Type 2 Tag data format ).
   • Set an NDEF message:

     
                 uint8_t ndef_msg_buf[] = ...;
                 
                  // Buffer with the user NDEF message
                 
                
     
                 uint32_t len           =
                 
                  sizeof
                 
                 (ndef_msg_buf);
                
     
                
     
                 
                  /* Set created message as the NFC payload. */
                 
                
     
                 err_code =
                 
                  nfc_t2t_payload_set
                 
                 (ndef_msg_buf, len);
                
     
                 
                  APP_ERROR_CHECK
                 
                 (err_code);
                

   • Alternatively, set a TLV structure:

     
                 uint8_t tlv_buf[] = ...;
                 
                  // Buffer with the user TLV structure
                 
                
     
                 uint32_t len           =
                 
                  sizeof
                 
                 (tlv_buf);
                
     
                
     
                 
                  /* Set created TLV structure as the NFC payload. */
                 
                
     
                 err_code =
                 
                  nfc_t2t_payload_raw_set
                 
                 (tlv_buf, len);
                
     
                 
                  APP_ERROR_CHECK
                 
                 (err_code);
                

     
     
     
3. Activate the NFC tag so that it starts sensing and reacts when an NFC field is detected:

   
             
              /* Start sensing NFC field. */
             
            
   
             err_code =
             
              nfc_t2t_emulation_start
             
             ();
            
   
             
              APP_ERROR_CHECK
             
             (err_code)