led_test.py

import serial
import time

# CONFIGURATION
# Check your port using 'ls /dev/tty*' in terminal
SERIAL_PORT = '/dev/ttyUSB0'  
BAUD_RATE = 115200

try:
    # Initialize Serial connection
    ser = serial.Serial(SERIAL_PORT, BAUD_RATE, timeout=1)
    
    # IMPORTANT: Wait for Arduino to reboot after serial connection is established
    print(f"Connecting to {SERIAL_PORT}...")
    time.sleep(2) 
    print("Connection established. Sending data...")

    while True:
        # Loop through numbers 1, 2, 3
        for value in [1, 2, 3]:
            # Convert to string, add newline, and encode to bytes
            command = f"{value}\n"
            ser.write(command.encode('utf-8'))
            
            print(f"Sent: {value}")
            
            # Wait 1 second before sending the next number
            time.sleep(1)

except serial.SerialException as e:
    print(f"Error opening serial port: {e}")
    print("Tip: Make sure you have permissions (sudo usermod -a -G dialout $USER)")

except KeyboardInterrupt:
    print("\nExiting script...")
    if 'ser' in locals() and ser.is_open:
        ser.close()