Can you evaluate why the following code for DESELECT function does not work ?
/* Deselect and switch off NFC RF field according
ISO/IEC 14443-4 B.2.3 Scenario 3 DESELECT
Comment Block No. (0) PCD PICC Block No. (1) Comment
1. rule 1 I(0)0 ===> 0 rule D
2. rule B 1 <=== I(0)0 rule 10
3. S(DESELECT) request ===>
4. <=== S(DESELECT) response rule 3
i-block is decoded in respnse trailer (sw1 sw2)
*/
export void NXP_NFC_Deselect()
{
/* I-Block */
NFC_WriteRegister3(NXP_REG_FIFODATA, 0x43, 0x00); // I(chaining 0) block=0, SW1+SW2: 01000011
NFC_ReadRegister3(NXP_REG_FIFODATA, 0x01, 0x00); // (00xxxxxx)b (not (00xxx101)b
/* S-Block(DESELECT) request, PCB 11000010b (CID 0), CID & NAD (optional fields), EDC (2 bytes, switched off) no INF field */
NFC_WriteRegister2(NXP_REG_FIFODATA, 0xc2);
/* ~4,8 ms max deactivation frame waiting time */
delay_ms(2);
/* S-Block(DESELECT) response */
if (!NFC_ReadRegister1(NXP_REG_FIFODATA, 0xc2)) // TODO supervisory 0001b
{
/* ~4,8 ms max deactivation frame waiting time */
delay_ms(2);
/* FIXMP Rule 8. If the S(DESELECT) request is not answered by an error-free S(DESELECT) response the S(DESELECT) request may be re-transmitted or the PICC may be ignored. */
NFC_ReadRegister1(NXP_REG_FIFODATA, 0xc2)
}
/* Disable NFC RF field */
NXP_NFC_RF_FIELD_OFF();
}
export void NXP_NFC_RF_FIELD_OFF()
{
/* switch RF field OFF */
NFC_Array_Write[0] = 0x86U;
NXP_NFC_WriteRegister(NXP_REG_DRVMODE, NFC_Array_Write, 0x01);
}
u8 NXP_NFC_ATQA()
{
/* Receive 16 bit ATQA */
if(2 != NFC_Array_Read[0U])
{
return NFC_APDU_ATQA_SIZE_ERROR;
}
/* bit 6, 13-16 is 0 */
if ((0x00 != (NFC_Array_Read[1U] && 0x20)) ||
(0x00 != (NFC_Array_Read[1U] && 0xF0)))
{
return NFC_APDU_ATQA_RFU_ERROR;
}
// FIXMP check further parameters
return TRUE;
}
