I initiate call with ATDxxx;
Until called party answeres or time-out, module does not respond any AT command.
No response even if I send “ATH” command.
After called party answered (conversation starts with no problem), call can be disconnected with ATH command.
Once call released either with timeout or with ATH command after answer module continues to work in the same way.
A bit about hardware;
- MCU supply is 2.8V
- DTR pin of SIM800C is connected to GND.
- Decoupling tantalum capacitor in 3mm distance
- Used PSU is capable of driving 3A.
- Changed module (with the same and different production dates), MCU, card… everything.
- If I connect Rx-Tx pins to SIM900D with the same software it works properly.
Any assistance highly appreciated.