Mbed cellular QIRD (read from tcpip connection) missing data

Mbed OS
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1

Hey. I’m trying to run a MQTT cliend with Quectel EC25 modem, using AT TCP/IP commands.
Since mbed does not support AT commands for EC25, I had do port the stack from BG96 modem. (which uses the same commands)

After few minutes of running, meaning, MQTT succesfully connects, and always at the same spot, I get some weird read error from the low level of the driver:

[INFO][CELL]: AT RX (18): <cr><ln>+QIRD: 0<cr><ln><cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX ( 8): AT+QIRD=
[INFO][CELL]: AT TX ( 1): 0
[INFO][CELL]: AT TX ( 1): ,
[INFO][CELL]: AT TX ( 1): 1
[INFO][CELL]: AT TX ( 1): <cr>
[INFO][CELL]: AT RX (18): <cr><ln>+QIRD: 0<cr><ln><cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX ( 8): AT+QIRD=
[INFO][CELL]: AT TX ( 1): 0
[INFO][CELL]: AT TX ( 1): ,
[INFO][CELL]: AT TX ( 1): 1
[INFO][CELL]: AT TX ( 1): <cr>
[INFO][CELL]: AT RX (18): <cr><ln>+QIRD: 0<cr><ln><cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX ( 8): AT+QIRD=
[INFO][CELL]: AT TX ( 1): 0
[INFO][CELL]: AT TX ( 1): ,
[INFO][CELL]: AT TX ( 1): 1
[INFO][CELL]: AT TX ( 1): <cr>
[INFO][CELL]: AT RX (13): <cr><ln>+QIRD<cr><ln>OK<cr><ln>
[ERR ][CELL]: Socket 0 recv error -1

Looking closely at this, I spotted that for some reason, the last +QIRD response is missing characters, which I’m guessing causes the error.

Sometimes it fails like so:

[INFO][CELL]: AT TX ( 8): AT+QIRD=
[INFO][CELL]: AT TX ( 1): 0
[INFO][CELL]: AT TX ( 1): ,
[INFO][CELL]: AT TX ( 1): 1
[INFO][CELL]: AT TX ( 1): <cr>
[INFO][CELL]: AT RX (13): <cr><ln>+QIR<ln><cr><ln>OK<cr><ln>

I’m running buffered serial with 115200 baud rate and flowcontrol (this baud rate is set as default on the modem)

Any insight would be greatly appreciated

2

If this is an STM32 processor, it may be this bug: STM32 processors cannot receive UART at even moderate baudrates while asleep · Issue #205 · mbed-ce/mbed-os · GitHub

The only known fix, I’m afraid, is to completely disable sleep on your processor.