So I have the weirdest problem I have ever encountered. I have sim 800 connected to atmega328 on a custom made PCB (ordered from china). the atmega sits on an atmega holder which is soldered to the pcb.
I run my code (worked perfect in the previous PCB iteration) and the modem doesn’t respond. BUT, if I heat the RX pin of the atmega with a soldering iron (so the solder is liquid) the modem starts responding perfectly.
after I remove the soldering iron the communication still works for a couple of minutes, after some time (5-30 minutes) the communication is lost again, until I heat it up again.
there is always a “short” when I test the connection between the atmega itself and the sim800, as it should be.
what is going on?
thanks in advance!