MC7304/54 CSD using QMI Mode


Using AT commands I have proved it is possible to use the AT/Modem interface in QMI mode to start a CSD (circuit switched data) call and send/receive data. Unfortunately while this call is active, this prevents any other AT commands from being sent on the interface and therefore blocks the application I am writing from accessing it (am using a combination of QMI commands and AT commands to control the modem.)

Is this a fixed behaviour in QMI and therefore is simultaneous CSD and AT commands only possible in DirectIP mode?



Is it also possible to control CSD calls via the QMI interface?

Hi Chris,

CSD is really old… and I am not able to test with local carriers as they no longer providing such service.

AFAIK, QMI supports voice features… Does it detect your CSD call ID? If yes, we may able to terminate it…

Also, maybe good to stop using AT cmd (to reserve the AT/modem port for CSD), but use QMI API to control and get modem status?

For Direct IP, I think it is more or less the same as QMI… as CSD supported only on AT port also.

Hope this helps.

Hi Lotam

Yes I agree, think we will go down the road of removing AT command for controlling device and use QMI instead. Save the AT/modem interface for CSD data transfer.