Chapter 26:

DIGITAL CLOCK

Creating a Clock with a 4-Digit 7-Segment Display on Raspberry Pi

Introduction

This guide will show you how to make a digital clock using a 4-digit 7-segment display connected to a Raspberry Pi.

1. Pin Setup:

• Assign GPIO pins to the segments of the display and the digits:

  • Segments: e (36), d (38), dp (40), c (32), g (29), b (12), f (16), a (18)

  • Digits: D4 (23), D3 (21), D2 (19), D1 (22)

2. Import Libraries and Initialize GPIO:

• Use the RPi.GPIO library for controlling GPIO pins and the datetime library for time:

  import RPi.GPIO as GPIO

  import time, datetime

3. Setup GPIO Ports:

• Configure each GPIO pin as an output and set it to low (off):

  segment8 = (18,12,32,38,36,16,29,40) for segment in segment8: GPIO.setup(segment, GPIO.OUT) GPIO.output(segment, 0) # Do the same for D4, D3, D2, D1

4. Define Digits and Characters:

• Create arrays for each digit (0-9) to represent their segment states.

5. Display Function:

• Define a function print_segment(charector) to control which segments are turned on based on the current digit.

6. Main Loop:

• Continuously get the current time and display it:

  • Break down the current hour and minute into individual digits.

  • Display each digit by activating the corresponding GPIO pins for a brief period to create a multiplexing effect.

This setup will display the current time on your 4-digit 7-segment display, updating every minute.

Note: Ensure that your GPIO pin numbers and wiring match the script. Test each segment individually for correct operation before running the full script. This project requires a basic understanding of electronics and Python programming.