How to Connect Django to Arduino via COM Port

Connecting a Django application to an Arduino via a COM port allows you to create innovative projects that blend web technologies with hardware control. In this blog post, we’ll walk through the steps needed to establish this connection, enabling you to control your Arduino board from a Django web application.

What You’ll Need

Django: A robust Python web framework.
Arduino: A versatile microcontroller board.
PySerial: A Python library for serial communication with the Arduino.
Arduino IDE: To program the Arduino.

Preparing the Arduino

First, configure your Arduino to listen for commands over the serial port. Here’s a basic example of an Arduino sketch that toggles an LED based on serial input:

int ledPin = 5;

void setup() {
    pinMode(ledPin, OUTPUT);
    Serial.begin(9600);
}

void loop() {
    if (Serial.available() > 0) {
        char command = Serial.read();
        if (command == '1') {
            digitalWrite(ledPin, HIGH); // Turn LED on
        } else if (command == '0') {
            digitalWrite(ledPin, LOW); // Turn LED off
        }
    }
}

Upload this code to your Arduino using the Arduino IDE.

Circuit Design

Installing PySerial

To enable Django to communicate with the Arduino, install the PySerial library:

pip install pyserial

Creating the Django View

Next, we’ll create a Django view to send commands to the Arduino. Below is an example:

from django.shortcuts import render
from django.http import HttpResponse
import serial

def control_led(request):
    if request.method == 'POST':
        command = request.POST.get('command')
        
        # Adjust the COM port and baud rate to match your Arduino settings
        ser = serial.Serial('COM3', 9600)
        ser.write(command.encode())
        ser.close()
        
        return HttpResponse('Command sent to Arduino')

    return render(request, 'control_led.html')

This view reads a command from a POST request, sends it to the Arduino via a serial connection, and then closes the connection.

Creating the HTML Template

Create an HTML template to provide an interface for sending commands to the Arduino:

<!DOCTYPE html>
<html>
<head>
    <title>Control Arduino LED</title>
</head>
<body>
    <h1>Control Arduino LED</h1>
    <form method="POST">
        {% csrf_token %}
        <button type="submit" name="command" value="1">Turn On</button>
        <button type="submit" name="command" value="0">Turn Off</button>
    </form>
</body>
</html>

Configuring URLs

Add a URL pattern to route requests to your new view. Update your urls.py:

from django.urls import path
from .views import control_led

urlpatterns = [
    path('control_led/', control_led, name='control_led'),
]

Testing the Connection

Start the Django development server:

python manage.py runserver

Navigate to http://127.0.0.1:8000/control_led/ in your web browser. You should see buttons to turn the LED on and off. Clicking these buttons will send commands to the Arduino via the serial port.

Conclusion

Following these steps, you can seamlessly connect your Django application to an Arduino via a COM port, allowing for innovative projects that integrate web technologies with hardware control. This opens up a world of possibilities for IoT projects, home automation, and more.

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Happy coding with Django and Arduino!