PRECV not working in binary command mode

LPWAN Modules / EVBs RAK3172
1

Please excuse my poor English.

I am checking P2P_LORA communication with the RAK3172 evaluation board.
I was able to communicate without problems in AT command mode (AT+ATM), but I cannot receive PRECV in binary command mode (AT+APM).
Setting PRECV in binary command mode seems to work well, and I can receive it when I switch to AT command mode with an ATM command.
Transmission is done in binary command mode.

The command settings are described below.
・PRECV command
{0x7E, 0x00, 0x08, 0x01, 0x00, 0x00, 0x04, 0x02, 0x3F, 0x00, 0x00, 0xFF, 0xFE, 0x18}
・PSEND command
{0x7E, 0x00, 0x08, 0x01, 0x00, 0x00, 0x04, 0x02, 0x3E, 0xAB, 0xCD, 0xEF, 0x12, 0x1B}

Do you have any advice?
Thank you.

2

Welcome to RAK forum @Fukuyama ,

Regarding your issue, it seems that the checksums you using are not correct. Can you try this?

・PRECV command
{0x7E, 0x00, 0x08, 0x01, 0x00, 0x00, 0x04, 0x02, 0x3F, 0x00, 0x00, 0xFF, 0xFE, 0x24}
・PSEND command
{0x7E, 0x00, 0x08, 0x01, 0x00, 0x00, 0x04, 0x02, 0x3E, 0xAB, 0xCD, 0xEF, 0x12, 0x27}

Please take note of the checksum calculator in the docs:

image
image1296×256 12.1 KB

3

Dear carlrowan, thank you very much for your reply.

I heard that there is a problem with the checksum, but I think the checksum is correct for the following reasons.
・The response when executing the PSEND binary command was normal.
{0x7E, 0x00, 0x05, 0x01, 0x01, 0x00, 0x01, 0x01, 0x3E, 0x00, 0x09}
・The response when executing the PRECV binary command was normal.
{0x7E, 0x00, 0x05, 0x01, 0x01, 0x00, 0x01, 0x01, 0x3F, 0x00, 0x0A}
・When the PSEND binary command was executed, if “AT+PRECV=65534” was specified in the RAK3172 on the other side in AT command mode, it could be received normally ("+EVT:RXP2P:-28:14:ABCDEF12.")
・After executing the PRECV binary command, when returning to AT command mode with “AT+ATM”, it was possible to receive normally.

Excuse me, but isn’t the checksum you pointed out in decimal?
24=0x18 , 27=0x1B

I can’t receive it when I switch to binary mode with “AT+APM” and execute the PRECV binary command, but after that I can receive it when I return to AT command mode with “AT+ATM”.

It is confirmed by connecting the evaluation board to the Linux machine via USB (eg /dev/ttyUSB0) and executing open()~write()~read() in the canonical mode of termios.
Can’t receive in binary mode = is there a problem with the read method?

Thank you very much.