SIM808: No communication when powering Arduino Mega

userHead Account cancelled 2019-04-23 22:55:53 2573 Views1 Replies

I'm powering the SIM808 shield with a 10 volts battery. Arduino Mega is powered through USB. Doing like this, the communications between both through the serial port 1 is OK.

However, when I also power Arduino with the 10 volts battery through Vin, the serial comunication stops to work. I've used another trafo (in order to try it with and independent power supply) but the result is the same. No communication.

Communication between PC and Arduino though USB to debug my code is always fine. GND of both circuits are connected together.

¿Does anyone know why this is happening?

2019-05-16 18:29:53 Power supply to mega from vin port without usb connection. Does mega work normally? userHeadPic techsupport