I have a doubt interfacing with fingerprint module (R305) with the Arduino Mega. I have been able to interface it to Arduino Uno before but not Arduino Mega so far.

I have used the Mega's hardware Serial1 pins 19 (Rx) and 18 (Tx) pins.

However, I am unable to get output from the module. How do I connect hardware serial and what is a sketch to do this?


1 Answer 1


Try Pin digital pins 0 (RX) and 1 (TX), as they also should be Serial0 on ArduinoMega (PWM 0 and 1)

see: https://www.arduino.cc/en/Reference/Serial

The Arduino Mega has three additional serial ports: Serial1 on pins 19 (RX) and 18 (TX), Serial2 on pins 17 (RX) and 16 (TX), Serial3 on pins 15 (RX) and 14 (TX). To use these pins to communicate with your personal computer, you will need an additional USB-to-serial adaptor, as they are not connected to the Mega's USB-to-serial adaptor. To use them to communicate with an external TTL serial device, connect the TX pin to your device's RX pin, the RX to your device's TX pin, and the ground of your Mega to your device's ground.

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