BG77 Main UART AT command always returns ERROR

IoT Modules LPWA Module
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1

I have a custom board with BG77.
On our previous (custom) eval board we used UART over USB to evaluate BG77 and we only tested dedicated main UART interface a bit.

Currently I work on the integration of BG77 with an application processor on a prototype board, where BG77 UARTs are connected to the application processor and the application processor issues AT commands.

My problem now is, that the BG77 responds by ERROR to any AT command except “ATI”, where response is provided, but ERROR is returned at the end as well.

(part of the) output parsed by the application processor (newlines replaced by semicolon)

ATI;Quectel;BG77;Revision: BG77LAR02A04;ERROR
AT+CFUN=1;ERROR
AT+COPS?;ERROR
AT+QNWINFO?;ERROR
AT+GSN?;ERROR

The GPIOs seems to be set-up correctly according to the startup sequence in datasheet, the STATUS PIN is HIGH prior issuing any command.

Could you please point me what could be the source of this issue?

2

We just found, that the problem was connected to the endlines I used to confirm command.

By a mistake, I used “\n\r”, not “\r” or “\r\n”, thus it let to the malformed command.

Strange think is, that response to “ATI\n\r” is provided …

3

I’m glad to hear that the problem has been solved