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Topic: MKR GSM 1400 + headset, get speach during TALKING state (Read 1 time) previous topic - next topic



When there is a call established (TALKING) state, how can i use a speaker and a microphone (headset) to be able to talk and listen ?

Do i have to include some audio library? do i need to convert signlas to sound? how does it work?


I had the same question, but also not found an answer. It looks as the used GSM module does not support analog signals, but has two I2S ports. One for RX sound and one for TX sound. This can be found in the schematic diagram on page 1 field B/7


Unfortunately it looks as they forgot to connect the pin 35 (I2S_TXD). This is the one that has to be used to receive the voice of the other side of the phone call. So even you have a I2S DA converter, you cannot connect it to that board. The pin 37 (I2S_RXD) is connected to the micro controller and can be used to replay audio data (as example WAV files from a SD card).

At least the system has an included DTMF decoder and DTMF generator. So it can be used as an automated answer machine to be controlled by DTMF tones over the air.

It will be really great, when there will be possible to bring out this two I2S wires in the next revision.


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