nfc change url

Question

Hi 
 Regarding the NFC url example there is any way to change the URL dynamically. My idea is to, at a certain point, be able to modify the URL configured during the setup. 
 I tried different approaches: 
 
 Simply calling "nfc_uri_msg_encode" with the new url (it changes the content of ndef_msg_buf) 
 Call "nfc_uri_msg_encode" and then register the ndef_msg_buf by calling "nfcSetPayload" 
 Call "nfcStopEmulation" -> "nfc_uri_msg_encode" -> "nfcSetPayload" -> "nfcStartEmulation" 
 
 However none of these approaches worked in my case, when I call the "nfcSetPayload" it returns an error and when I change only the encoded message ("nfc_uri_msg_encode") I am able to get the tag with a smartphone but it return an empty tag. 
 Any one knows a way to dynamically change the url of a nfc tag? 
 Thanks in advance

Nuno Figueiredo · Accepted Answer

Hi 
 Based on the code of Einar I was able to find the solution. It is necessary only to change a simple detail in the code to make it work. We need to pass the reference to the first element of the ndef_msg_buf. I left the code of a function that allows to change dynamically the nfc tag. 
 void change_nfc_tag()
{

 uint8_t ret_val, err_code;

 ret_val = nfcStopEmulation();
 if (ret_val != NFC_RETVAL_OK)
 {
 APP_ERROR_CHECK((uint32_t) ret_val);
 }
 
 
 /* The new URL */
 char url2[50];
 uint32_t len2 = sizeof(ndef_msg_buf2);
 memset(url2,'0',sizeof(url3));
 sprintf(url2,"nordicsemi.com"); //you can use format to construct the string. Take care with the size limit (50 in my case)

 /* Encode URI message into buffer */
 err_code = nfc_uri_msg_encode( NFC_URI_HTTP_WWW,
 (uint8_t *) url2,
 sizeof(url2),
 &ndef_msg_buf2[0],
 &len2);
 
 APP_ERROR_CHECK(err_code);
 /** @snippet [NFC URI usage_1] */

 /* Set created message as the NFC payload */
 ret_val = nfcSetPayload( (char*)ndef_msg_buf2, len2);
 if (ret_val != NFC_RETVAL_OK)
 {
 APP_ERROR_CHECK((uint32_t) ret_val);
 }
 
 /* Start sensing NFC field */
 ret_val = nfcStartEmulation();
 if (ret_val != NFC_RETVAL_OK)
 {
 APP_ERROR_CHECK((uint32_t) ret_val);
 }
}

nfc change url

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