client: Specify license

[tattlekey] / client / button.c

/* tattlekey: A one-key UDP keyboard
 * Copyright (C) 2023  Scott Worley <scottworley@scottworley.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#include "button.h"
#include "config.h"

#include "hardware/gpio.h"

#include "pico/stdlib.h"

static callback_t button_callback = NULL;

static void respond_to_gpio_interrupt(uint gpio, uint32_t event_mask) {
  if (gpio == config_button_pin && event_mask & GPIO_IRQ_EDGE_FALL &&
      button_callback) {
    button_callback();
  }
}

void begin_listening_for_button_press(callback_t callback) {
  button_callback = callback;

  gpio_set_pulls(config_button_pin, 1, 0);

  /* Allow some time for the pull-up to take effect.
   * I'm not sure if this is necessary.
   * https://datasheets.raspberrypi.com/pico/raspberry-pi-pico-c-sdk.pdf says
   * the internal GPIO pull-up resistors are 50k. */
  sleep_ms(100);

  gpio_set_irq_enabled_with_callback(config_button_pin, GPIO_IRQ_EDGE_FALL, 1,
                                     respond_to_gpio_interrupt);
}