Hi guys, this is my first question in arduino forum,
I'm trying to connect SIM800L (my first time using GSM/GPRS protocols) but I have faced a problem
I made a simple softwareSerial code to read and write from serial, without sending any AT command the serial print infinite amount of question mark!
For the information I powered the chip 4.2 volts and it kept blinking for 1 sec (7 times the stops for the 8th)
When I powered it to 6v 2A the led indicator shows it's connected to the SIM card then the ? Appears in serial monitor
I checked the voltage from arduino Tx it sends 2.8 v to the chip
After uploading a calling code to my SIM800L the regular ? Showed but it did make the call!!
Any help please?