TRF7964A: Software question about TRF7964A

Hi TI Teams,

We have some question about the software of TRF7964A, the details are as follows:

1) An exception occurred while writing the TRF7964A register in continuous mode:

The SPI mode is used to communicate with TRF7964A. When the TRF7964A register is read or written in single mode or continuous read mode, the write value is consistent with the read value, and the MCU and TRF7964A can communicate normally. However, when the instruction 0x20 is sent to the register of TRF7964A in continuous write mode (write continuously from register address 0x00), the set value is sent in the sequence of register address. It is found that the read values are different from the written values (All value are zero).

At this point, write to the TRF7964A register in normal single mode or send command code 0x83(command 0x03, Software initialization), the TRF7964A cannot communicate normally. Only when the EN foot of the TRF7964A is restarted, the TRF7964A can communicate normally.

2) RF transmit byte length does not match TX length registers (0x1D, 0x1E)

The power supply voltage of TRF7964A is 3.3V, and the frequency is 13.56MHz, RF communication is set to ISO14443-A, communication data rate is 106Kbit/s, operation procedure is as below:

->Send 0x03(Software initialization command), 0x00(Idle command), and 0x0f(Reset FIFO command).

->Setting register value: 

0x00:0x20, 
0x01:0x88, 
0x03:0x18, 
0x04:0x00, 
0x05:0x08, 
0x06:0x20, 
0x07:0x0e, 
0x08:0x07, 
0x09:0x01, 
0x0A:0x00, 
0x0B:0x86,
0x10:0x2A, 
0x11:0x01, 
0x14:0x0f,

3) Send 0x0f(Reset FIFO command), send 0x10(Transmission without CRC command), write register address 0x1D: 0x00, write register address 0x1E: 0x10(set send byte length 1 byte), write register address 0x1F: 0x26 (RF card search instruction);

4) Detect the IQR pin level reading register address 0x1C(FIFO status) of TRF7964A; An oscilloscope was used to detect the TX_OUT pin of TRF7964A and it was found that the actual transmitting code length was greater than one byte of transmitting length set in registers 0x1D and 0x1E (note: RF card was not placed on the RF antenna).

Thanks,

Kind Regards