40pin IO Development

Experiment 02 - GPIO Input

Hardware Connection

Connect the button circuit to IO37 (you can use a DuPont wire instead of a button).

Software Operation

Enter the user home directory and run:

cd user
sudo python3 ./GPIO_input.py

Terminal as shown:

You can see that when the button is pressed, the terminal outputs low level; when released, the terminal outputs high level.

#!/usr/bin/env python3
import sys
import signal
import Hobot.GPIO as GPIO
import time

def signal_handler(signal, frame):
    sys.exit(0)

# Define GPIO channel 37
input_pin = 37 # BOARD pin 37

GPIO.setwarnings(False)

def main():
    prev_value = None

    # Set pin numbering mode to BOARD
    GPIO.setmode(GPIO.BOARD)
    # Set to input mode
    GPIO.setup(input_pin, GPIO.IN)

    print("Starting demo now! Press CTRL+C to exit")
    try:
        while True:
            # Read pin level
            value = GPIO.input(input_pin)
            if value != prev_value:
                if value == GPIO.HIGH:
                    value_str = "HIGH"
                else:
                    value_str = "LOW"
                print("Value read from pin {} : {}".format(input_pin, value_str))
                prev_value = value
            time.sleep(1)
    finally:
        GPIO.cleanup()

if __name__=='__main__':
    signal.signal(signal.SIGINT, signal_handler)
    main()