Raspberry Pi 4 Project 01

LED Bar Graph Pulsating Project

This project involves creating a 10-LED bar graph that pulsates light using a Raspberry Pi 4 and Python code. The LED bar graph will have 10 bars, each controlled by a GPIO pin on the Raspberry Pi.

Required Materials

To complete this project, you will need the following materials:

• Raspberry Pi 4
• Breadboard
• 10 LEDs
• 10 220-ohm resistors
• Jumper wires

Circuit Diagram

The circuit diagram for this project is shown below:

File:LED Bar Graph Pulsating Circuit Diagram.png

In this diagram, each LED is connected to a GPIO pin on the Raspberry Pi through a 220-ohm resistor. The GPIO pins used for each LED are as follows:

• LED 1: GPIO 21
• LED 2: GPIO 20
• LED 3: GPIO 16
• LED 4: GPIO 12
• LED 5: GPIO 7
• LED 6: GPIO 8
• LED 7: GPIO 25
• LED 8: GPIO 24
• LED 9: GPIO 23
• LED 10: GPIO 18

Python Code

The Python code for this project is shown below:

    # Wait a short amount of time
    time.sleep(0.05)

# Decrease the duty cycle from 100 to 0 in steps of 5
for dc in range(100, -5, -5):
    # Set the duty cycle for each LED
    for i in range(len(led_pins)):
        GPIO.output(led_pins[i], dc > (i*10))
        # ^^^ If the duty cycle is greater than the threshold for this LED, turn it on.

    # Wait a short amount of time
    time.sleep(0.05)