I'm trying to make a communication between Arduino Uno and a SIM800l.
My shield can be connected to 5V so I've connected it to a PC power supply, assuring the 2A current.
The problem is when I receive the information from SIM800l before sending a command like "AT", the only responses I have are strange characters like "á" or "ÿ". I've tried it with software serial ports and hardware ports on an Arduino Mega too. The baud rate is configured at 9600.