Assignment 2: Joystick Mouse Control

Objective

The goal of this assignment is to interface an Arduino Uno with a Python script on your computer. You will read the X and Y coordinates from a joystick module using the Arduino's analog-to-digital converter (ADC). These coordinates will then be sent to your computer via the serial port. A Python script will read this serial data and use it to control the position of your mouse pointer on the screen.

This project will teach you about:

• Reading analog sensors with analogRead().
• Serial communication between an Arduino and a PC.
• Writing a Python script to interact with serial ports.
• Controlling system-level functions (like the mouse) with Python.
• Mapping values from one range to another (sensor range to screen resolution).

Hardware & Software Requirements

• Arduino Uno R3 Board
• USB-A to USB-B Cable
• Joystick Module (PS2 Style)
• Jumper Wires (Male-to-Female)
• A computer with Arduino IDE and Python installed.

Part 1: The Arduino Side - Reading and Sending Data

First, we need to wire the joystick to the Arduino and write a sketch to read its values and send them over the serial port.

Circuit Diagram

Connect your joystick module to the Arduino Uno as shown below. Joystick modules typically have 5 pins:

• GND: Connect to GND on the Arduino.
• +5V: Connect to 5V on the Arduino.
• VRx: The X-axis output. This is an analog signal. Connect to an analog pin (e.g., A0).
• VRy: The Y-axis output. This is an analog signal. Connect to another analog pin (e.g., A1).
• SW: The switch/button press. We will not use this pin for this assignment.

Arduino Sketch

The Arduino sketch should perform these steps in a loop:

1. Read the analog value from the X-axis pin (A0).
2. Read the analog value from the Y-axis pin (A1).
3. Format these two values into a single string, separated by a comma (e.g., "512,510").
4. Send this string over the serial port using Serial.println().
5. Add a small delay to avoid flooding the serial port with too much data.

Here is a starter code snippet. You will need to complete it.

// Define the analog pins connected to the joystick
#define VRX_PIN A0 // Joystick X-axis
#define VRY_PIN A1 // Joystick Y-axis

void setup() {
  // Initialize serial communication at a 9600 bits-per-second baud rate.
  // This rate must match the rate used in your Python script.
  Serial.begin(9600);
}

void loop() {
  // Read the analog values from the joystick
  int xValue = analogRead(VRX_PIN);
  int yValue = analogRead(VRY_PIN);

  // Print the values to the serial port in a "x,y" format
  Serial.print(xValue);
  Serial.print(",");
  Serial.println(yValue); // println adds a newline character at the end

  // A small delay to make the communication stable
  delay(50); 
}

Upload this code to your Arduino Uno. You can check if it's working by opening the Serial Monitor in the Arduino IDE (Tools > Serial Monitor). Make sure the baud rate is set to 9600. You should see a stream of numbers like 512,511 that change as you move the joystick.

Part 2: The Python Side - Receiving Data and Controlling the Mouse

Now we will write a Python script to read the data from the Arduino and move the mouse.

Python Environment Setup

You will need two Python libraries: pyserial to read from the serial port and pyautogui to control the mouse. Open your terminal or command prompt and install them using pip:

pip install pyserial
pip install pyautogui

Test Function: Reading from the Serial Port

# test_serial.py
import serial
import time

# --- IMPORTANT ---
# CHANGE 'COM3' to your Arduino's port.
# You can find this in the Arduino IDE under Tools > Port.
# For Mac/Linux, it will be something like '/dev/tty.usbmodemXXXX'
ARDUINO_PORT = 'COM3' 
BAUD_RATE = 9600

try:
    # Establish a serial connection
    arduino = serial.Serial(ARDUINO_PORT, BAUD_RATE, timeout=1)
    time.sleep(2) # Wait for the connection to establish

    print(f"Connected to Arduino on {ARDUINO_PORT}. Reading data...")
    print("Move your joystick to see the values change.")
    print("Press Ctrl+C to exit.")

    while True:
        # Read one line of data from the serial port
        data = arduino.readline()

        # Check if any data was received
        if data:
            # Decode the bytes into a string and remove leading/trailing whitespace
            decoded_data = data.decode('utf-8').strip()
            print(f"Received: {decoded_data}")

except serial.SerialException as e:
    print(f"Error: Could not open port {ARDUINO_PORT}. {e}")
except KeyboardInterrupt:
    print("\nProgram terminated by user.")
finally:
    if 'arduino' in locals() and arduino.is_open:
        arduino.close()
        print("Serial port closed.")

Run this script from your terminal: python test_serial.py. If everything is set up correctly, you should see the same coordinate stream that you saw in the Arduino Serial Monitor.

Main Task: Controlling the Mouse

Once your test script works, you can move on to the main task. You need to modify the script to:

1. Parse the incoming string (e.g., "512,510") to get separate X and Y integer values.
2. Get the size of your computer screen.
3. Map the joystick's analog values (0 to 1023) to your screen's pixel coordinates (e.g., 0 to 1920 for width, 0 to 1080 for height).
4. Use the mapped coordinates to move the mouse pointer using pyautogui.moveTo().

Hints for the Main Script

Here is a skeleton to guide you. You need to fill in the logic inside the `while` loop.

# joystick_mouse.py
import serial
import pyautogui
import time

# --- Configuration ---
ARDUINO_PORT = 'COM3' # CHANGE THIS to your Arduino's port
BAUD_RATE = 9600

# Get screen dimensions
screenWidth, screenHeight = pyautogui.size()
print(f"Screen size: {screenWidth} x {screenHeight}")

# Establish serial connection
arduino = serial.Serial(ARDUINO_PORT, BAUD_RATE)
time.sleep(2) # Wait for connection

print("Starting mouse control. Move the joystick.")
print("Press Ctrl+C to exit.")

try:
    while True:
        # 1. Read a line from the Arduino
        data = arduino.readline().decode('utf-8').strip()

        # 2. Make sure the data is not empty
        if data:
            try:
                # 3. Split the string into two parts and convert to integers
                x_str, y_str = data.split(',')
                x_val = int(x_str)
                y_val = int(y_str)

                # 4. Map the joystick values (0-1023) to screen coordinates
                # The joystick's X-axis might be inverted, so we map 1023-0 instead of 0-1023.
                # You might need to adjust this based on your joystick's orientation.
                mouseX = (x_val * screenWidth) / 1023
                mouseY = (y_val * screenHeight) / 1023
                
                # 5. Move the mouse to the new coordinates
                pyautogui.moveTo(mouseX, mouseY)

            except (ValueError, IndexError):
                # Handle cases where the data is not in the expected "x,y" format
                print(f"Warning: Received malformed data: {data}")
                continue

except KeyboardInterrupt:
    print("\nProgram terminated.")
finally:
    arduino.close()

Submission

Please submit the following files in a single ZIP archive named YourName_Assignment2.zip:

1. Your final Arduino sketch file (.ino).
2. Your final Python script file (.py).
3. A short video (max 30 seconds) demonstrating your project in action. Show the joystick moving and the mouse pointer responding on the screen.

Grading Rubric