app/ticker.c


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#include "project.h"

static volatile uint32_t delay_ms_count;
static uint32_t scale = 35;

volatile uint32_t ticks;

void
delay_us (uint32_t d)
{
  d *= scale;

  while (d--)
    __asm__ ("nop");
}

void
sys_tick_handler (void)
{
  static int slow;

  if (delay_ms_count)
    delay_ms_count--;

  ticks++;

  led_tick();
  cdcacm_tick();

  slow++;

  if (slow < 1000)
    return;

  slow = 0;

  ptp_slow_tick();

  ref_slow_tick();
  steth_slow_tick();
  led_slow_tick();
}


void
delay_ms (uint32_t d)
{
  delay_ms_count = d;

  while (delay_ms_count);
}


void
ticker_init (void)
{
  uint32_t v, w;

  /*168MHz 1ms */
  systick_set_reload (168000);
  systick_set_clocksource (STK_CSR_CLKSOURCE_AHB);
  systick_counter_enable();
  /* this done last */
  systick_interrupt_enable();


  /*Calibrate the delay loop */

  do {
    scale--;
    v = ticks;

    while (v == ticks);

    delay_us (1000);
    w = ticks;
    v++;
    w -= v;
  } while (w);

  SCS_DEMCR |= SCS_DEMCR_TRCENA;
  SCS_DWT_CTRL |= SCS_DWT_CTRL_CYCCNTENA;

}