How does Arduino board communicate with Python?

 Arduino and Python can communicate seamlessly, and this is one of the most popular ways to control hardware from a PC or log sensor data for analysis. Here’s the breakdown:

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1. The Communication Channel

• Arduino boards usually communicate with a computer through a USB cable.

• That USB port is internally a serial (UART) interface, exposed as a COM port (Windows) or /dev/ttyUSB0 / /dev/ttyACM0 (Linux/Mac).

• So the key mechanism is serial communication.

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2. Arduino Side

On Arduino, you write a sketch that uses the built-in Serial library:

void setup() {
  Serial.begin(9600);  // Start serial at 9600 baud
}

void loop() {
  int sensorValue = analogRead(A0);  
  Serial.println(sensorValue);       // Send data to Python
  delay(100);
}

• Serial.begin(9600) sets the baud rate.

• Serial.print() / Serial.println() sends data.

• Serial.read() / Serial.parseInt() can receive commands from Python.

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3. Python Side

On the Python side, you use a serial communication library.
The most common is PySerial.

Install:

pip install pyserial

Example Code:

import serial
import time

# Open serial port (adjust COM port / baudrate)
arduino = serial.Serial('COM3', 9600, timeout=1)
time.sleep(2)  # wait for Arduino to reset

# Send command to Arduino
arduino.write(b'Hello Arduino\n')

# Read data from Arduino
while True:
    data = arduino.readline().decode('utf-8').strip()
    if data:
        print("Received:", data)

• Opens a serial connection to the Arduino.

• Reads sensor values sent via Serial.println().

• Can also send commands (like turning LEDs on/off).

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4. Use Cases

• Data Logging: Send sensor readings (temperature, humidity, etc.) from Arduino to Python for plotting with Matplotlib or storing in a database.

• Remote Control: Python sends commands to Arduino (e.g., robot movement commands).

• Real-time Visualization: Python GUI (Tkinter, PyQt) can visualize Arduino sensor data live.

• Machine Learning + Control: Python runs ML algorithms, then tells Arduino how to control motors/actuators.

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5. Other Communication Methods

Besides basic serial:

• Firmata Protocol: Arduino runs a standard sketch (StandardFirmata), and Python (via pyFirmata) can directly control pins without writing custom Arduino code.

• Networking: With Wi-Fi (ESP8266/ESP32) or Ethernet shields, Arduino and Python can talk via TCP/UDP, MQTT, or HTTP.

• Bluetooth (HC-05/HC-06): Serial over wireless.

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In summary:
Arduino communicates with Python primarily through serial communication over USB, using Arduino’s Serial library and Python’s pyserial. This setup allows bi-directional communication for logging, controlling, or building complex interactive systems.