Duplex serial communication between Arduino and Raspberrypi

 Duplex serial communication between Arduino and Raspberrypi

Raspberrypi Setup 

Detect the Arduino board

When connecting the Arduino with a USB cable, you should see it appear as /dev/ttyACM0 or /dev/ttyUSB0 (sometimes the number can be different, for example /dev/ttyACM1).

Simply open terminal and run the following command. 

Run

ls /dev/tty*

and you should see it. At this point if you’re not sure which device is the Arduino board, simply disconnect the board (remove the USB cable), and run the above command again. This way you will easily spot the serial device name of your Arduino. For example in following pictures will observe the difference while running command before and after inserting arduino USB cable.

Before inserting USB

After inserting USB

Here the difference is there is added a port red marked.

Install Python Serial library on Raspberry Pi

You need to install a library to be able to use the Serial interface with Python.

To install it:

Run

python3 -m pip install pyserial

This Python library is well-known and used in a lot of applications.

When installing, if you get an error such as “/usr/bin/python3: No module named pip”, then you need to install pip first with 

Run

sudo apt install python3-pip

and Run

Sudo pip3 install pyserial.

Code for Raspberrypi

import serial                                         # Module needed for serial communication

import time

if __name__ == '__main__':

#change port instead ttyUSB0 by following above setup step.

    ser = serial.Serial('/dev/ttyUSB0', 9600, timeout=1)

    ser.flush()

    while (1):

        send_string = ("My name is Raspberry Pi\n")

  # Send the string. Make sure you encode it before you send it to the Arduino.

        ser.write(send_string.encode('utf-8'))

  # Do nothing for 500 milliseconds (0.5 seconds)

        time.sleep(1)

  # Receive data from the Arduino

        receive_string = ser.readline().decode('utf-8').rstrip()

        print(receive_string)

Code for arduino

void setup() {

  Serial.begin(9600);

}

void loop() {

  if (Serial.available() > 0) {

    String data = Serial.readStringUntil('\n');

    Serial.print("You sent me: ");

    Serial.println(data);

  }

}