I am trying to interface a cell phone to an arduino serial port. Like the serial2mobile library, except using the actual serial port instead of softwareSerial.
I have used the software serial library to send data to the phone and it works fine. But I want to use the serial port instead. When I plug in the TX, RX and GND wires to the phone from the arduino, the screen starts to flicker. I can communicate with the phone from a PC without any problems using a blueSmirf hooked directly to the phone. Can anyone help me figure out why I cant communicate to the phone through just the arduino on the Serial port?
Are the signal voltages different from the bluesmirf and the arduino?