Voice calls possible? And battery required always?

[Lynge]

Hi
I have been asked to create a simple "emergency" phone. I have been looking at all kinds of products to put this together. Both for arduino and raspberry pi (or other sbc).

Now that the MRKGSM1400 has launched I see that the library contains something about making voice calls, but what about actually transmitting voice from a microphone and playing back incoming voice via a speaker? Is this possible with this board?
I see that the SARAU201 has some pins for audio as "4-wire I2S digital audio interface" can the MCU use that or do I need extra hardware or is it not possible at all with this arduino?

Any suggestions are welcome

If I can use the MKRGSM1400 does it always require a battery to use the GSM modem? What if I supply it with from a very beefy psu on VIN?

Again, any help would be greatly appreciated

[Zombiezzz]

Hi,

I wonder the same thing. Are there anyone in this forum who knows how MKR1400 works regarding speech/voice and knows if it is possible to have actual voiceCall for both sending/receiving?

[sandeepmistry]

Please see this project for a tutorial on outgoing voice calls and wave file playback: https://create.arduino.cc/projecthub/Arduino_Genuino/arduino-mkr-gsm-1400-and-i2s-2a48b6?f=1


Unfortunately is it not possible to receive income voice data over I2S.

I'd highly recommend a lipo battery, you could also try to use a beefy power supply with capacitors to handle the current spikes.

[mzocher]

Looking at the schematic (https://content.arduino.cc/assets/MKRGSM1400-schematic.pdf), the modem has the i2s receive pin connected but not the i2s transmit pin.  So the modem has the capability, but it was never wired up to the processor?


I'll admit, I'm a bit bummed this fact wasn't on the product page.  I'm doing a rotary phone conversion, and would have selected a different board.

Is it possible to use an AT command on the SARA-U201 board to change the I2S_RXD GPIO pin to work as an I2S transmit pin?  I'm still trying to translate their AT documentation (https://www.u-blox.com/sites/default/files/u-blox-CEL_ATCommands_%28UBX-13002752%29.pdf) myself.