protab/timer2-irq/timer.c

   1 #include <libopencm3/cm3/nvic.h>
   2 #include <libopencm3/stm32/rcc.h>
   3 #include <libopencm3/stm32/gpio.h>
   4 #include <libopencm3/stm32/timer.h>
   5
   6 void tim3_isr(void)
   7 {
   8         if (TIM_SR(TIM3) & TIM_SR_UIF) {
   9                 TIM_SR(TIM3) &= ~TIM_SR_UIF;
  10                 gpio_toggle(GPIOC, GPIO13);
  11         }
  12 }
  13
  14 int main(void)
  15 {
  16         rcc_clock_setup_in_hse_8mhz_out_72mhz();
  17         rcc_periph_clock_enable(RCC_GPIOC);
  18         rcc_periph_clock_enable(RCC_TIM3);
  19
  20         // PC13 = BluePill LED
  21         gpio_set_mode(GPIOC, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO13);
  22
  23         timer_set_prescaler(TIM3, 35999);       // 72 MHz / 36000 = 2 kHz
  24         timer_set_mode(TIM3, TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP);
  25         timer_set_period(TIM3, 199);            // 200 ticks = 100 ms
  26         timer_update_on_overflow(TIM3);
  27         timer_enable_irq(TIM3, TIM_DIER_UIE);
  28         nvic_enable_irq(NVIC_TIM3_IRQ);
  29         timer_enable_counter(TIM3);
  30
  31         for (;;) {
  32                 asm volatile ("wfi");
  33         }
  34
  35         return 0;
  36 }