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1.1.3 LED Bar Graph

Introduction

In this project, we sequentially illuminate the lights on the LED Bar Graph.

Required Components

In this project, we need the following components.

../_images/list_led_bar.png

It’s definitely convenient to buy a whole kit, here’s the link:

Name

ITEMS IN THIS KIT

LINK

Raphael Kit

337

Raphael Kit

You can also buy them separately from the links below.

COMPONENT INTRODUCTION

PURCHASE LINK

GPIO Extension Board

BUY

Breadboard

BUY

Jumper Wires

BUY

Resistor

BUY

LED Bar Graph

-

Schematic Diagram

T-Board Name

physical

wiringPi

BCM

GPIO17

Pin 11

0

17

GPIO18

Pin 12

1

18

GPIO27

Pin 13

2

27

GPIO22

Pin 15

3

22

GPIO23

Pin 16

4

23

GPIO24

Pin 18

5

24

GPIO25

Pin 22

6

25

SDA1

Pin 3

8

2

SCL1

Pin 5

9

3

SPICE0

Pin 24

10

8
../_images/schematic_led_bar.png

Experimental Procedures

Step 1: Build the circuit.

Note

Pay attention to the direction when connecting. If you connect it backwards, it will not light up.

../_images/image66.png

Step 2: Go to the folder of the code.

cd ~/raphael-kit/python/

Step 3: Run the executable file.

sudo python3 1.1.3_LedBarGraph.py

After the code runs, you will see the LEDs on the LED bar turn on and off regularly.

Code

Note

You can Modify/Reset/Copy/Run/Stop the code below. But before that, you need to go to source code path like raphael-kit/python. After modifying the code, you can run it directly to see the effect.

import RPi.GPIO as GPIO
import time

ledPins = [11, 12, 13, 15, 16, 18, 22, 3, 5, 24]

def oddLedBarGraph():
    for i in range(5):
        j = i*2
        GPIO.output(ledPins[j],GPIO.LOW)
        time.sleep(0.3)
        GPIO.output(ledPins[j],GPIO.HIGH)

def evenLedBarGraph():
    for i in range(5):
        j = i*2+1
        GPIO.output(ledPins[j],GPIO.LOW)
        time.sleep(0.3)
        GPIO.output(ledPins[j],GPIO.HIGH)

def allLedBarGraph():
    for i in ledPins:
        GPIO.output(i,GPIO.LOW)
        time.sleep(0.3)
        GPIO.output(i,GPIO.HIGH)

def setup():
    GPIO.setwarnings(False)
    GPIO.setmode(GPIO.BOARD)        # Numbers GPIOs by physical location
    for i in ledPins:
        GPIO.setup(i, GPIO.OUT)   # Set all ledPins' mode is output
        GPIO.output(i, GPIO.HIGH) # Set all ledPins to high(+3.3V) to off led

def loop():
    while True:
        oddLedBarGraph()
        time.sleep(0.3)
        evenLedBarGraph()
        time.sleep(0.3)
        allLedBarGraph()
        time.sleep(0.3)

def destroy():
    for pin in ledPins:
        GPIO.output(pin, GPIO.HIGH)    # turn off all leds
    GPIO.cleanup()                     # Release resource

if __name__ == '__main__':     # Program start from here
    setup()
    try:
        loop()
    except KeyboardInterrupt:  # When 'Ctrl+C' is pressed, the program destroy() will be  executed.
        destroy()

Code Explanation

ledPins = [11, 12, 13, 15, 16, 18, 22, 3, 5, 24] Create an array and assign it to the pin number corresponding to the LED Bar Graph (11, 12, 13, 15, 16, 18, 22, 3, 5, 24) and the array will be used to control the LED.

def oddLedBarGraph():
    for i in range(5):
        j = i*2
        GPIO.output(ledPins[j],GPIO.LOW)
        time.sleep(0.3)
        GPIO.output(ledPins[j],GPIO.HIGH)

Let the LED on the odd digit of the LED Bar Graph light on in turn.

def evenLedBarGraph():
    for i in range(5):
        j = i*2+1
        GPIO.output(ledPins[j],GPIO.LOW)
        time.sleep(0.3)
        GPIO.output(ledPins[j],GPIO.HIGH)

Make the LED on the even digit of the LED Bar Graph light on in turn.

def allLedBarGraph():
    for i in ledPins:
        GPIO.output(i,GPIO.LOW)
        time.sleep(0.3)
        GPIO.output(i,GPIO.HIGH)

Let the LED on the LED Bar Graph light on one by one.

Phenomenon Picture

../_images/image67.jpeg