Raspberry Pi Pico: How to Read a Push Button

				
					#include <stdio.h>
#include "pico/stdlib.h"
#include "hardware/gpio.h"


// Define the GPIO pins based on your circuit setup
#define LED_PIN 25
#define BUTTON_PIN 21


int main()
{
  // 1. Initialize Standard I/O (for printf over USB serial)
    stdio_init_all();
    printf("--- Pico Push Button Input Demo Started! ---\n");
   
    // 2. Configure LED Pin (Output)
    gpio_init(LED_PIN);
    gpio_set_dir(LED_PIN, GPIO_OUT);
    gpio_put(LED_PIN, 0); // Start with LED OFF
    printf("LED (GPIO %d) configured as output.\n", LED_PIN);

    // 3. Configure Button Pin (Input with Pull-Up)
    gpio_init(BUTTON_PIN);
    gpio_set_dir(BUTTON_PIN, GPIO_IN); // Set pin as input
   
    // Enable internal PULL-UP resistor. Input is HIGH (1) when button is open.
    gpio_pull_up(BUTTON_PIN);
    printf("Button (GPIO %d) configured as input with pull-up. Active LOW.\n", BUTTON_PIN);

    bool led_state = false; // Tracks the current state of the LED
    int last_button_state = 1; // Start state: Unpressed (HIGH)

    while (true) {
        // Read the current state of the button (0 = Pressed, 1 = Unpressed)
        int current_button_state = gpio_get(BUTTON_PIN);
       
        // Detect a transition from Unpressed (1) to Pressed (0)
        if (current_button_state == 0 && last_button_state == 1) {
           
            // A press event occurred (rising edge detection in reverse)
            led_state = !led_state; // Toggle the LED state
            gpio_put(LED_PIN, led_state); // Apply the new state to the LED
           
            printf(">>> Button Pressed! LED Toggled to %s. <<<\n", led_state ? "ON" : "OFF");
           
            // Short delay for rudimentary software debouncing
            sleep_ms(50);
        }
       
        // Update the last state for the next loop iteration
        last_button_state = current_button_state;
       
        // Prevent excessive CPU usage
        sleep_ms(10);
    }
    return 0;
}