Writing to Mifare Ultralight C with PN532 library for Arduino Uno - nfc

Question

I use the sample code to read from MIFARE Ultralight and write to MIFARE Classic, with the definition in .h file:
#define PN532_RESPONSE_INDATAEXCHANGE (0x41)
#define MIFARE_CMD_WRITE (0xA0)
but when I run the code below:
/**************************************************************************/
uint8_t PN532::mifareultralight_WritePage (uint8_t page, uint8_t *buffer1)
{
/* Prepare the first command */
pn532_packetbuffer[0] = PN532_COMMAND_INDATAEXCHANGE;
pn532_packetbuffer[1] = 1; /* Card number */
pn532_packetbuffer[2] = MIFARE_CMD_WRITE; /* Mifare Write command = 0xA0 */
pn532_packetbuffer[3] = page; /* Page Number (0..63 in most cases) */
memcpy (pn532_packetbuffer + 4, buffer1, 4); /* Data Payload */
/* Send the command */
if (HAL(writeCommand)(pn532_packetbuffer, 8)) {
Serial.println(F("Go here 1"));
return 0;
}
Serial.println(F("Go here 2"));
/* Read the response packet */
return (0 < HAL(readResponse)(pn532_packetbuffer, sizeof(pn532_packetbuffer)));
}
The result would be like this:
Scan a NFC tag
write: 4A 1 0
read: 4B 1 1 0 44 0 7 4 C1 37 CA 2C 2C 80
ATQA: 0x 44SAK: 0x 0
Writing Mifare Ultralight
write: 40 1 30 4
read: 41 0 2 0 0 10 0 6 1 10 11 FF 0 0 0 0 0 0
write: 40 1 30 3
read: 41 0 0 0 0 0 2 0 0 10 0 6 1 10 11 FF 0 0
Tag capacity 0 bytes
write: 40 1 A0 5 1 2 3 4
Go here 2
Write failed 0
It does not go into "Go here 1", it means that no write command to the reader, do anyone know why?

Answer 1

That write command you are using seems to be wrong. You are using the COMPATIBILITY_WRITE command code (0xA0) but you pass the parameters of a WRITE command.
I suggest you stick to the WRITE command:
+-----------+------+------+---------------------+
| WRAPPING | CMD | ADDR | DATA (1 PAGE) |
+-----------+------+------+---------------------+
| 0x40 0x01 | 0xA2 | 0x05 | 0x01 0x02 0x03 0x04 |
+-----------+------+------+---------------------+
Or you could also use the COMPATIBILITY_WRITE command:
You start with sending the command and the address:
+-----------+------+------+
| WRAPPING | CMD | ADDR |
+-----------+------+------+
| 0x40 0x01 | 0xA0 | 0x05 |
+-----------+------+------+
You should then receive the ACK/NAK status from the tag.
Then you send the data in a second frame:
+-----------+---------------------+------------------------------------------------------------+
| WRAPPING | DATA (1 PAGE) | FILLER (3 EMPTY PAGES)
+-----------+---------------------+------------------------------------------------------------+
| 0x40 0x01 | 0x01 0x02 0x03 0x04 | 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+-----------+---------------------+------------------------------------------------------------+