Python program 5: Interfacing Motor Relay with Raspberry Pi for ON/OFF Control

Objective:

To interface a motor relay with Raspberry Pi and write a Python program to control its ON/OFF operation.

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Resources Required:

• Raspberry Pi (any model)
• DC Motor
• Relay Module
• Jumper wires

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Theory:

A relay is an electrically operated switch. In this experiment, we are using a single-channel relay module to control a DC motor using the GPIO pin of the Raspberry Pi.

The relay has two sides:

• Input Side (control side connected to Raspberry Pi)

• Output Side (switching side connected to the motor and power source)

Relay Indicators:

• Red LED: Lights up when the relay board is powered.

• Green LED: Lights up when the relay is activated (ON state).

Switching Logic:

• If the orange cable is connected to the bottom slot, the motor will be OFF/ON depending on the relay state.

• If connected to the upper slot, the motor will be ON/OFF depending on the relay state.

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Circuit Diagram

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Python Code:

Below is the Python program to control the motor ON/OFF operation using a relay module.

import RPi.GPIO as GPIO
import time

# Suppress warnings and reset GPIO state
GPIO.setwarnings(False)
GPIO.cleanup()

# Set pin numbering to BCM
GPIO.setmode(GPIO.BCM)

# Define the pin connected to the relay module
pin1 = 22

# Set the relay pin as output
GPIO.setup(pin1, GPIO.OUT)

try:
    while True:
        # Turn motor ON
        GPIO.output(pin1, True)
        print("Motor ON")
        time.sleep(5)

        # Turn motor OFF
        GPIO.output(pin1, False)
        print("Motor OFF")
        time.sleep(5)

except KeyboardInterrupt:
    GPIO.cleanup()
    print("Program stopped and GPIO cleaned up.")
    exit()

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Result:

• When the program is executed, the relay switches ON and OFF every 5 seconds.
• The motor connected through the relay follows the ON/OFF logic as per the GPIO output.
• The red LED lights up when power is supplied to the relay board.
• The green LED lights up when the motor is powered (relay activated).

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Conclusion:

This experiment demonstrates how a Raspberry Pi can control the ON/OFF operation of a motor using a relay module. The program alternates the GPIO output, which switches the relay and thus controls the motor.

The successful toggling of the motor validates the working of GPIO-controlled relay-based switching.

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Assignments:

1. Two-Way Motor Control:
   Write a Python program to control motor direction (clockwise and anticlockwise) using two relay modules.

2. Soil Moisture Controlled Motor:
   Write a Python program to interface a soil moisture sensor with Raspberry Pi. Based on the moisture level, turn the motor ON/OFF using a relay.

🕒 Check back in the comments tomorrow to see if your solution matches the correct one!