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Displaying Numbers on a 7-Segment Display Using a Push Button with Raspberry Pi Pico

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The objective of this experiment is to interface a common cathode 7-segment display with a Raspberry Pi Pico, and control the number shown on the display using a single push button. Each time the button is pressed, the display should increment the number from 1 up to 9. Once 9 is reached, the next button press should cycle it back to 1. This experiment demonstrates the use of digital output for segment control, digital input for reading a switch, and basic logic to track and update numeric values on hardware displays.

Buy Basic Raspberry Pi Pico Kit

Items Required:

Connections:

7-Segment Display (Common Cathode):

  • Segment a → GPIO 0
  • Segment b → GPIO 1
  • Segment c → GPIO 2
  • Segment d → GPIO 3
  • Segment e → GPIO 4
  • Segment f → GPIO 6
  • Segment g → GPIO 7
  • Common cathode pins → GND (both cathode pins if available)
  • ·  One terminal of the push button → GPIO 5
  • ·  Other terminal of the push button → GND

Code:

from machine import Pin
import time

# Define segment GPIOs for a to g
segments = [
    Pin(0, Pin.OUT),  # a
    Pin(1, Pin.OUT),  # b
    Pin(2, Pin.OUT),  # c
    Pin(3, Pin.OUT),  # d
    Pin(4, Pin.OUT),  # e
    Pin(6, Pin.OUT),  # f
    Pin(7, Pin.OUT)   # g
]

# Define digit to segment mapping for common cathode
digit_segments = [
    # a b c d e f g
    [0,1,1,0,0,0,0],  # 1
    [1,1,0,1,1,0,1],  # 2
    [1,1,1,1,0,0,1],  # 3
    [0,1,1,0,0,1,1],  # 4
    [1,0,1,1,0,1,1],  # 5
    [1,0,1,1,1,1,1],  # 6
    [1,1,1,0,0,0,0],  # 7
    [1,1,1,1,1,1,1],  # 8
    [1,1,1,1,0,1,1]   # 9
]

# Push button pin
button = Pin(5, Pin.IN, Pin.PULL_UP)

count = 0

def display_digit(n):
    if 1 <= n <= 9:
        pattern = digit_segments[n - 1]
        for i in range(7):
            segments[i].value(pattern[i])
    else:
        # Turn off all segments
        for seg in segments:
            seg.value(0)

# Start with display off
display_digit(0)

# Main loop
while True:
    if button.value() == 0:  # Button pressed (active low)
        count += 1
        if count > 9:
            count = 1
        display_digit(count)
        time.sleep(0.3)  # Debounce and prevent multiple counts
        # Wait for release
        while button.value() == 0:
            time.sleep(0.01)
    time.sleep(0.01)

Download Code:

Result:

When the Raspberry Pi Pico is powered on, the 7-segment display remains off initially. On the first button press, the number “1” appears on the display. Each subsequent press increments the number shown, going from 1 to 9. After 9, pressing the button again will wrap the count back to 1, and the cycle continues.

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