AT+CBC SIMCom modem supply voltage

[kgmuzungu]

@lewisxhe on my board it is resulting in 0.013V .... can you check? all supply pins of the modem's really connected?

[lewisxhe]

Please see the schematic diagram, this modem ADC is not connected to any circuit and has no function.

[kgmuzungu]

There are commands AT+CADC and AT+CADC2 in chapter 11 to read the ADCs. AT+CBC should read the supply voltage.

[lewisxhe]

This is a software definition. There is no actual hardware circuit connected to the modem's ADC pin, so it is invalid. You can only use the https://github.com/Xinyuan-LilyGO/LilyGO-T-A76XX/tree/main/examples/ReadBattery sketch to read the battery voltage.

[kgmuzungu]

The A7670E has one ADC pin. It can be read with AT+CADC. It is not connected as you wrote.

I am referring to the command AT+CBC in this issue. It reads the VBAT voltage, the chips supply voltage. This is N O T the ADC pin! On my board it reads 0.013V. Something is not right. Check on your boards.

[lewisxhe]

I just checked the manual. If I'm not mistaken, AT+CBC relies on an external ADC to get the voltage. I will ask SIMCOM for confirmation. It's still a holiday now, so I'll ask them in a few days.

[kgmuzungu]

pls find all data about my firmware and model here, issue 117

[lewisxhe]

It has been confirmed that the conditions obtained by AT+CBC are not met, so 0 is returned.

[kgmuzungu]

The SIMCom documantations are so poorly written 😢 It might be as you say. But there is no reference that AT+CBC reads the ADC pin.

Can you provide the source document you are citing?

BTW What does 'perfom partial external pressure' mean?