EG25-G PCM in slave mode not working?

Hello I am currently developing a project and I would like to use PCM of EG25-G modem as slave. The default (master) seems to work fine but the slave configuration of my microntroller is a little bit buggy and I would like to use the modem as slave instead.

I configure the modem with this AT command: AT+QDAI=1,1,0,1,0,0
However I dont get samples from the modem. I tried probing an oscilloscope when the call was active and I wouldnt get a response. Sometimes I would get some glitches though. The same pin works fine if the modem is master.

Does the modem require another Master clock (additionally to bit clock, and frame synchro)? If yes in what pin??

Thank you

Dear Nalexopoiti,
Thanks for your inquiry in Quectel forum.
About your issue, please make sure whether you use our recommended CODEC chipset, if not, it may can not support it. Please check the following information. Thanks!

Due to project requirements I cannot use directly the recommended codecs and I have to do it with a microcontroller inbetween. That is why I choose io option number 1.

So you confirm that the EG25-G PCM can work as slave in primary mode?? I am familiar with the above information but the pdf I have is primarily for EC25.

LTE Module Series
Rev. EC25&EC21_AT_Commands_Manual_V1.3
Date: 2018-09-20
Status: Released

Dear Nalexopoiti,
Yes, EG25G pcm can work as slave in primary mode, you can use our recommended codec chipset to confirm it. Thanks!