Code Examples

Turn Onboard LED On

The Raspberry Pi Pico board has a green LED already connected to GPIO 25. Following code configures GPIO 25 as an output and turns the LED on.

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

#define LED_PIN 25                  // Define a pin number macro to use it throughout the code

int main()
{
    gpio_init(LED_PIN);             // Initialize GPIO 25 to the default state
    gpio_set_dir(LED_PIN, true);    // Configure GPIO 25 as an output
    gpio_put(LED_PIN, true);        // Drive GPIO 25 to High

    while (true);
}

Blink Onboard LED

Following code blinks the onboard LED and then an external LED connected to GPIO 16

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

#define ledPin1 25
#define ledPin2 16

void setup()
{
   stdio_init_all();
   gpio_init(ledPin1);  // Initialize GPIO 25
   gpio_init(ledPin2); // Initialize GPIO 16
   gpio_set_dir(ledPin1,true); // Configure GPIO 25 as an output
   gpio_set_dir(ledPin2,true); // Configure GPIO 16 as an output

    
}

void loop()
{
   
    gpio_put(ledPin1,true); //Turn GPIO 25 on
    sleep_ms(1000); //Pause 1000 miliseconds
    gpio_put(ledPin1,false); //Turn GPIO 25 off
    sleep_ms(1000); //Pause 1000 miliseconds
    
    gpio_put(ledPin2,true); //Same thing for external LED but blinking rate is 0.2 s
    sleep_ms(200);
    gpio_put(ledPin2,false);
    sleep_ms(200);
  
}

int main()
{
    setup();

    while (true)
        loop();
}

Read HIGH or LOW using a GPIO

Following code configures a GPIO as an input. The exact configuration can be set by changing values in gpio_set_pulls function.

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

#define inPin 15

void setup()
{
    stdio_init_all();

    gpio_init(inPin); // Configure GPIO 15 as an input
    gpio_set_dir(inPin,false); // Configure GPIO 15 as an input
    gpio_set_pulls(inPin,0,0); // Set GPIO input as floating (0,0), pull down (0,1) or pull up (1,0) 
}

void loop()
{
    bool x = gpio_get(inPin); // Read GPIO state, i.e. HIGH or LOW
    printf("%u\r\n",x); // Print out the GPIO state as 1 or 0
    sleep_ms(200); //Sleep to give the print function time to work properly
}

int main()
{
    setup();
    while (true)
        loop();
}

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