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exti_rising_falling.c
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exti_rising_falling.c
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/*
* This file is part of the libopencm3 project.
*
* Copyright (C) 2009 Uwe Hermann <uwe@hermann-uwe.de>,
* Copyright (C) 2010 Piotr Esden-Tempski <piotr@esden.net>
*
* This library is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This library 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
#include <libopencm3/stm32/rcc.h>
#include <libopencm3/stm32/gpio.h>
#include <libopencm3/cm3/nvic.h>
#include <libopencm3/stm32/exti.h>
#define FALLING 0
#define RISING 1
uint16_t exti_direction = FALLING;
/* Set STM32 to 72 MHz. */
static void clock_setup(void)
{
rcc_clock_setup_pll(&rcc_hse_configs[RCC_CLOCK_HSE8_72MHZ]);
}
static void gpio_setup(void)
{
/* Enable GPIOC clock. */
rcc_periph_clock_enable(RCC_GPIOC);
/* Set GPIO12 (in GPIO port C) to 'output push-pull'. */
gpio_set_mode(GPIOC, GPIO_MODE_OUTPUT_50_MHZ,
GPIO_CNF_OUTPUT_PUSHPULL, GPIO12);
}
static void exti_setup(void)
{
/* Enable GPIOA clock. */
rcc_periph_clock_enable(RCC_GPIOA);
/* Enable AFIO clock. */
rcc_periph_clock_enable(RCC_AFIO);
/* Enable EXTI0 interrupt. */
nvic_enable_irq(NVIC_EXTI0_IRQ);
/* Set GPIO0 (in GPIO port A) to 'input open-drain'. */
gpio_set_mode(GPIOA, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, GPIO0);
/* Configure the EXTI subsystem. */
exti_select_source(EXTI0, GPIOA);
exti_direction = FALLING;
exti_set_trigger(EXTI0, EXTI_TRIGGER_FALLING);
exti_enable_request(EXTI0);
}
void exti0_isr(void)
{
exti_reset_request(EXTI0);
if (exti_direction == FALLING) {
gpio_set(GPIOC, GPIO12);
exti_direction = RISING;
exti_set_trigger(EXTI0, EXTI_TRIGGER_RISING);
} else {
gpio_clear(GPIOC, GPIO12);
exti_direction = FALLING;
exti_set_trigger(EXTI0, EXTI_TRIGGER_FALLING);
}
}
int main(void)
{
clock_setup();
gpio_setup();
exti_setup();
while (1)
__asm("nop");
return 0;
}