Update README.md and fix ndef record tnf name

Author: RJRP44

README.md

@@ -13,9 +13,59 @@ This is a library for ST's [ST25DV-I2C series](https://www.st.com/en/nfc/st25dv-
 * [Ndef](#ndef)
 * [Example](#example)
 ### Ndef
-The ndef support is not complete, only the external record can be writen. Feel free to improve it and add other records support.
+This library contains a basic implementation of ndef to read or write data. However, more specific data types like uri and text require their formats to be added.
+
+For simple write you can use this function `st25dv_ndef_write_content` as shown :
+```c
+st25dv_config st25dv_config = {
+        ST25DV_USER_ADDRESS,
+        ST25DV_SYSTEM_ADDRESS
+};
+
+char record_type[] = "android.com:pkg";
+char record_payload[] = "fr.ouchat.app";
+
+std25dv_ndef_record record = {
+            NDEF_ST25DV_TNF_EXTERNAL,
+            record_type,
+            record_payload
+};
+
+st25dv_ndef_write_content(st25dv_config, &address, mb, me, ndef_record);
+```
+Arguments of the function :
+- `st25dv_config` is your st25dv config
+- `address` is the pointer of the value for the memory address, after writing it is updated to the end of what was written
+- `mb` stands for "message begin" and should be true is this record is the first one
+- `me` stands for "message end" and should be true for the last record
+- `ndef_record` contains 3 values:
+  - `tnf` : Type Name Format, witch describes the content format. Theses are all the values :
+    - `0x00` : Empty
+    - `0x01` : Well known
+    - `0x02` : Mime
+    - `0x03` : URI
+    - `0x04` : External
+    - `0x05` : Unknown
+    - `0x06` : Unchanged
+    - `0x07` : Reserved
+  - `record_type` : The name of your record type 
+  - `record_payload` : The payload
+
+To read data you can use this function `st25dv_ndef_read`
+
+```c
+std25dv_ndef_record *read = malloc(sizeof(std25dv_ndef_record));
+memset(read, 0 , sizeof(std25dv_ndef_record));
+
+uint8_t record_num = 2;
+uint8_t record_count = 0;
+st25dv_ndef_read(st25dv_config, record_num,read, &record_count);
+
+//Delete record after use
+st25dv_ndef_delete_records(read);
+```
 ### Example
-You can find in the `📁 /examples` folder an example project demonstrating the main features of the library.
+You can find in the `📁 /examples` folder an example project showcasing the main features of the library to help you understand how it works.
 
 ## 📝 License
 

include/st25dv_ndef.h

@@ -37,14 +37,14 @@
 #define NDEF_ST25DV_TNF_RESERVED 0x07
 
 typedef struct {
-    uint8_t ndef_type;
+    uint8_t tnf;
     char *type;
     char *payload;
 } std25dv_ndef_record;
 
 esp_err_t st25dv_ndef_write_ccfile(uint64_t ccfile);
 
-static esp_err_t st25dv_ndef_write_content(st25dv_config st25dv, uint16_t *address, bool mb, bool me, std25dv_ndef_record record);
+esp_err_t st25dv_ndef_write_content(st25dv_config st25dv, uint16_t *address, bool mb, bool me, std25dv_ndef_record record);
 esp_err_t st25dv_ndef_write_app_launcher_record(st25dv_config st25dv, uint16_t *address, bool mb, bool me, char *app_package);
 esp_err_t st25dv_ndef_write_json_record(st25dv_config st25dv, uint16_t *address, bool mb, bool me, cJSON *json_data);
 

st25dv_ndef.c

@@ -14,7 +14,7 @@ esp_err_t st25dv_ndef_write_ccfile(uint64_t ccfile) {
     return st25dv_write(ST25DV_USER_ADDRESS, 0x00, ccbyte, sizeof(ccfile));
 }
 
-static esp_err_t st25dv_ndef_write_content(st25dv_config st25dv, uint16_t *address, bool mb, bool me, const std25dv_ndef_record record) {
+esp_err_t st25dv_ndef_write_content(st25dv_config st25dv, uint16_t *address, bool mb, bool me, const std25dv_ndef_record record) {
     uint8_t type_size = strlen(record.type);
     uint16_t payload_size = strlen(record.payload);
 
@@ -45,7 +45,7 @@ static esp_err_t st25dv_ndef_write_content(st25dv_config st25dv, uint16_t *addre
     tnf |= me ? NDEF_ST25DV_ME : 0;
     tnf |= payload_size > 0xFF ? 0 : NDEF_ST25DV_SR;
     tnf |= NDEF_ST25DV_IL;
-    tnf |= record.ndef_type;
+    tnf |= record.tnf;
     *data++ = tnf;
 
     //Type length
@@ -245,7 +245,7 @@ esp_err_t st25dv_ndef_read(st25dv_config st25dv, uint8_t record_num, std25dv_nde
 
         if(*record_count == record_num){
             //Add payload type to the output
-            output_records->ndef_type = payload_type;
+            output_records->tnf = payload_type;
 
             //Get type and add it to the output
             char *type = malloc(type_length + 1);