AT APDU issue without prefix response

[stich86]

Hi @estkme,

me and my friends are playing with a Fibocom FM-350GL module that support eSIM provisioing using AT (it should works also over MBIM but not using USB mode). Now the big problem is that AT commands responds without put back the prefix of the called command, here is an example:

~# lpac chip info
AT_DEBUG: AT+CCHO=?
AT_DEBUG:
AT_DEBUG: OK
AT_DEBUG: AT+CCHC=?
AT_DEBUG:
AT_DEBUG: OK
AT_DEBUG: AT+CGLA=?
AT_DEBUG:
AT_DEBUG: OK
AT_DEBUG: T+CCHC=1
AT_DEBUG:
AT_DEBUG: OK
AT_DEBUG: AT+CCHO="A0000005591010FFFFFFFF8900000100"
AT_DEBUG: AT+CGLA=1,22,"81E2910006BF3E035C015A"
AT_DEBUG:
AT_DEBUG: 1
AT_DEBUG:
AT_DEBUG: OK

I was testing a modification to the loop in the close channel function, which currently counts up to 4. This module throws an error if the AT+CCHC command is sent without including 1.

In the test output, for the CGLA command, we see no reply as expected (+CGLA: 1), but only 1. A friend of mine reworked part of the AT PDU handling logic, but I think it can be improved further.

Here’s the repository for reference: https://github.com/SuperKali/lpac.

Do you have any suggestions? @SuperKali and I are happy to test any modifications you propose. Could you also help refine or correct the code?

Thanks in advance!

[stich86]

@CoelacanthusHex are you able to help us? Thanks!