Python Program 1 : Interfacing LED/Buzzer with Raspberry Pi

OBJECTIVE:

To interface an LED or Buzzer with the Raspberry Pi and write a program to control it using delays.

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RESOURCES REQUIRED:

• Raspberry Pi (any model with GPIO support)
• 330Ω Resistor
• LED (Light Emitting Diode)
• Breadboard
• Jumper wires

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THEORY:

• LED Basics:

  • An LED has two legs: Anode (+) and Cathode (-).

  • The longer leg is the Anode (positive), and the shorter leg is the Cathode (negative).

• Current Limiting Resistor:

  • A 330Ω resistor is connected in series with the LED.

  • This resistor limits the current flowing through the LED to prevent it from burning out.

  • Without this resistor, the LED might draw too much current and get damaged.

• GPIO Pins on Raspberry Pi:

  • The Raspberry Pi comes with General Purpose Input/Output (GPIO) pins.

  • These pins can be programmed to act as either input or output.

  • We can connect components like LEDs or buzzers to these pins to control them through Python programs.

• Circuit Design:

  • The Anode of the LED is connected to GPIO pin (e.g., GPIO 18).

  • The Cathode is connected to the ground through a 330Ω resistor.

  • The GPIO pin is programmed to send HIGH or LOW signals to turn the LED ON or OFF.

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Python Code: Controlling LED with Raspberry Pi

import RPi.GPIO as GPIO
import time
pin = 18  # GPIO pin to which LED is connected
# Set the pin numbering mode to BCM
GPIO.setmode(GPIO.BCM)
# Set GPIO pin 18 as output
GPIO.setup(pin, GPIO.OUT)
try:
    while True:
        GPIO.output(pin, True)  # Turn ON LED
        time.sleep(2)           # Wait for 2 seconds
        GPIO.output(pin, False) # Turn OFF LED
        time.sleep(2)           # Wait for 2 seconds
except KeyboardInterrupt:
    GPIO.cleanup()             # Reset GPIO settings
    exit()
Explanation of the Program:

1. Import Libraries:

   • RPi.GPIO is used to control GPIO pins.

   • time is used to create time delays.

2. Pin Setup:

   • pin = 18 sets GPIO pin 18 for LED connection.

   • GPIO.setmode(GPIO.BCM) configures pin numbering mode as BCM (Broadcom chip-specific).

   • GPIO.setup(pin, GPIO.OUT) sets pin 18 as an output pin.

3. Main Loop:

   • The while True: loop runs indefinitely.

   • GPIO.output(pin, True) turns the LED ON.

   • time.sleep(2) creates a 2-second delay.

   • GPIO.output(pin, False) turns the LED OFF.

   • Another 2-second delay is added before repeating.

4. Exit Handling:

• The program runs until you press Ctrl + C.

• On exit, GPIO.cleanup() resets the GPIO pins to a safe state.

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📘 Assignment: Drop your answer in the comments below!
Task: Write a Python program for a Binary Counter using Raspberry Pi.

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