stm32-better-blink/main.c

/*
 * My first project
 *
 * It blinks LEDs like counting in binary, when the button is pressed, it reverses the order
 *
 * Build on top of libopenocm3, blackbox parts of code (setup()) copied from
 * libopencm3-examples/examples/stm32/f1/stm32vl-discovery/button project
 *
 * Open source licence, let's say Artistic Licence, although it doesn't matter, as it is local only
 */

#include <libopencm3/stm32/rcc.h>
#include <libopencm3/stm32/gpio.h>
#include <stdbool.h>

#define DELAY 8000000		// Should be a second, or maybe not (second iff 8MHz clk, 1/3second if 24MHz clk)
#define STM32F1 1			// Needed for libopencm3

void setup (void) {			// All the blackbox code
	rcc_clock_setup_in_hse_8mhz_out_24mhz();
	rcc_periph_clock_enable(RCC_GPIOC);
	rcc_periph_clock_enable(RCC_GPIOA);
	gpio_set_mode(GPIOC, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO8 | GPIO9);
	gpio_set_mode(GPIOA, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, GPIO0);
}

void inline wait (int ticks) {	// This works in libopenocm3 examples
	int i;
	for (i=0;i<ticks;i++) __asm__("nop");
	return;
}

int main (void) {
	setup();

	gpio_unset(GPIOC, GPIO8 | GPIO9);
	while (gpio_get(GPIOA, GPIO0) == 0);

	// Array of what leds should be on
	uint16_t states[4] = {0, GPIO9, GPIO8, GPIO9 | GPIO8};
	enum {FORWARD, BACKWARD} direction = FORWARD;
	bool pressed = true;
	char state;

	while (true) {
		if (/*Button pressed, but was not*/ gpio_get(GPIOA, GPIO0) && (pressed == false) ) {
			pressed = true;
			direction = (direction == FORWARD ? BACKWARD : FORWARD);	// Switch direction
		} else /*Button not pressed, possibly released*/ {
			pressed = false;
		}
		state = (direction == FORWARD ? (state + 1)%4 : (/*state+4-1*/ state+3)%4 );

		gpio_set(GPIOC, states[state]);		//FIXME: This doesn't work, as it does not write 0s to unmentioned pins!! 
		wait(DELAY);
	}
	return 0;
}