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// vim: shiftwidth=4 tabstop=4 noexpandtab
#include <libopencm3/stm32/rcc.h>
#include <libopencm3/stm32/gpio.h>
/*
SYSCLK should be at 72.000.000 Hz
--> 18.000.000 __asm__("nop") per second (one instruction --> 4 clock cycles)
--> 18.000 __asm__("nop") per millisecond
*/
#define DELAY_MS 18000 // FIXME seems to be too slow by factor of 4
static void clock_init(void);
static void gpio_init(void);
static void delay(uint32_t delay);
void main(void)
{
clock_init();
gpio_init();
while(1){
gpio_toggle(GPIOC, GPIO13);
delay(250 * DELAY_MS);
}
}
static void clock_init(void)
{
rcc_clock_setup_pll(&rcc_hse_configs[RCC_CLOCK_HSE8_72MHZ]);
rcc_periph_clock_enable(RCC_GPIOC); // for PC13 blinking
}
static void gpio_init(void)
{
gpio_set_mode(GPIOC, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO13);
gpio_set(GPIOC, GPIO13);
}
static void delay(uint32_t delay)
{
for (uint32_t i = 0; i < delay; i++) {
__asm__("nop");
}
}
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