sim800l goes to sleep after a while

[dimentiy89]

in my ttgo-tcall, sim800l constantly goes to sleep, only a hard reboot helps. How can I disable sleep mode??

[MKElias]

The sleep mode or slow clock mode of SIM800l is controlled by DTR pin.

In TTGO T-Call the GPIO_32 of ESP32 is connected to the DTR pin of SIM800l. So, if you are using the GPIO_32 on your code for any other purpose then it might be causing the issue. If that is the case, try changing the GPIO_32 pin to another GPIO pin.

Or, if you really need the GPIO_32 pin and do not want to use/control sleep mode then there is an AT command that can make SIM800l ignore the DTR pin state. Which is AT&D0 in the AT command manual "Set DTR Function Mode".