Control a 7 Segment Display from Raspberry PI with Python

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7 segment display is a simple electronic display composed of 7 (surprise) LEDs. It is common to find an addictional led for a little dot near classic 7 segments. It runs in a very simple way with Raspberry PI GPIOs and Python coding

7 digit display

In this tutorial I’m going t show you how to connect and configure a 7 segment display with a Raspberry PI. If you are searching for “4 digit-7 segment display” guide, you may be interested in my 4 Digit diplay tutorial.

7 segment display is used within a wide number application, usually to single a display number. These devices have a simple internal wiring diagrams, which maps one by one LEDs to its pins:

7 digit display pin

In this article we’ll control a 7 Segment Display from a Raspberry PI Zero W. This article applies also to newer Raspberry PI computer boards.

What We Need

Raspberry PI Zero WH board

As usual, I suggest adding from now to your favourite e-commerce shopping cart all needed hardware, so that at the end you will be able to evaluate overall costs and decide if continue with the project or remove them from the shopping cart. So, hardware will be only:

Many of listed hardware (except from Raspberry PI Zero W and micro SD Card) can be bought alone or can be also found in the useful Elegoo starter kit.

Check hardware prices with following links:

Amazon raspberry pi boards box
Amazon Raspberry PI 3 Model A+ box
Amazon raspberry pi Zero W box
amazon raspberry pi pico box
Amazon Micro SD box
Amazon Raspberry PI Power Supply box
Amazon Resistors box
Amazon Breadboard box
Amazon Dupont Wiring box

Step-by-Step Procedure

Wiring Diagram

Prepare cabling according to following wiring diagram:

RPI 7 digit display wiring

This wiring produces the following mapping between Display and Raspberry PI:

Display SegmentDisplay PinRaspberry PI phisical pinRaspberry PI BCM GPIO
A71117
B61327
C41522
D21910
E1219
F92311
G10295
DP5316
GRD36GRD
GRD86GRD

So, each Raspberry PI pin / GPIO powers on/off its related segment. Powering on appropriated segments together will display the number we want to show.

Please find below the overall picture:

RPI 7 segment Display picture

OS Preparation

Start with OS installation using install Raspberry PI OS Lite guide. This procedure also works with Raspberry PI OS Desktop, using its internal terminal.

Make your OS up-to-date. From the terminal, use the following commands:

sudo apt update
sudo apt upgrade

RPI.GPIO should be already installed (otherwise, you can get it installed with the command “sudo apt install python3-rpi.gpio”).

Get 7 Segment Python Script

Get segDisplay.py script from my download area:

wget https://peppe8o.com/download/python/segDisplay.py

This script will be explained later in this post.

Script Usage

This script can be used by simply calling segDisplay.py with a simple argument passing the number to display and the dot (if required). So, for example:

python3 segDisplay.py 1.

Will display the number “1” and powers ON the dot led.

python3 segDisplay.py 5

Will display the number “5” and powers OFF the dot led.

python3 segDisplay.py 10

Will power OFF the whole display.

Script explaination

First section imports required libraries

import sys
import RPi.GPIO as GPIO

This script works mapping following pins activation according to wiring diagram:

Num_to Display -> GPIO pins state
0 -> [1,1,1,1,1,1,0]
1 -> [0,1,1,0,0,0,0]
2 -> [1,1,0,1,1,0,1]
3 -> [1,1,1,1,0,0,1]
4 -> [0,1,1,0,0,1,1]
5 -> [1,0,1,1,0,1,1]
6 -> [1,0,1,1,1,1,1]
7 -> [1,1,1,0,0,0,0]
8 -> [1,1,1,1,1,1,1]
9 -> [1,1,1,1,0,1,1]
10 (OFF) -> [0,0,0,0,0,0,0]

Dot GPIO (6) is managed alone. The last array is used to deactivate the Display.

GPIO id order is stored in a simple array. GPIO order is according to mapping. GPIOs are also all set as output.

display_list = [17,27,22,10,9,11,5]
GPIO.setmode(GPIO.BCM)

GPIO.setwarnings(False)
for pin in display_list:
 GPIO.setup(pin,GPIO.OUT) # setting pins
 GPIO.setup(6,GPIO.OUT) # setting dot pin
GPIO.setwarnings(True)

Warnings are disabled because this script will leave display active after execution.

A new array is defined, listing all possible combinations to Display. So, arrSeq[0] stores GPIO status to show “0” on display. arrSeq[10] will be managed alone to push a GPIO.cleanup.

arrSeg = [[1,1,1,1,1,1,0],\ # -> arrSeq[0] displays 0
 [0,1,1,0,0,0,0],\ # -> arrSeq[1] displays 1
 [1,1,0,1,1,0,1],\ # -> arrSeq[2] displays 2
 [1,1,1,1,0,0,1],\ # -> arrSeq[3] displays 3
 [0,1,1,0,0,1,1],\ # -> arrSeq[4] displays 4
 [1,0,1,1,0,1,1],\ # -> arrSeq[5] displays 5
 [1,0,1,1,1,1,1],\ # -> arrSeq[6] displays 6
 [1,1,1,0,0,0,0],\ # -> arrSeq[7] displays 7
 [1,1,1,1,1,1,1],\ # -> arrSeq[8] displays 8
 [1,1,1,1,0,1,1]] # -> arrSeq[9] displays 9

Then a basic error check on the passed argument is performed. On error, program exits:

if len(sys.argv) > 2:
 print("ERROR: too many arguments")
 sys.exit()
elif len(sys.argv) == 1:
 print("ERROR: missing argument")
 sys.exit()
elif int(sys.argv[1].replace(".", "")) > 10 or int(sys.argv[1].replace(".", ""))<0:
 print("ERROR: insert a number between 0 and 10")
 sys.exit()

Dot led activation is managed alone, so the only number is passed to the main diplay procedure:

if sys.argv[1].count(".") == 1:GPIO.output(6,1)
numDisplay = int(sys.argv[1].replace(".", ""))

The final operation is just activating GPIOs according to the number passed on the argument. This script then exits:

if numDisplay == 10: GPIO.cleanup()
else: GPIO.output(display_list, arrSeg[numDisplay])

sys.exit()

Enjoy!

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