1 files changed, 60 insertions, 0 deletions
diff --git a/app/ticker.c b/app/ticker.c
new file mode 100644
index 0000000..ea832c8
--- /dev/null
+++ b/app/ticker.c
@@ -0,0 +1,60 @@
+#include "project.h"
+
+
+static volatile uint32_t ticks;
+static uint32_t scale = 30;
+
+unsigned led = 32000;
+
+void
+delay_us (uint32_t d)
+{
+  d *= scale;
+
+  while (d--)
+    __asm__ ("nop");
+}
+
+void
+sys_tick_handler (void)
+{
+  timex_tick();
+  cdcacm_tick();
+
+  ticks++;
+
+  if (led) {
+    gpio_clear (LED_BANK, LED_GPIO);
+    led--;
+  } else
+    gpio_set (LED_BANK, LED_GPIO);
+
+}
+
+
+void
+ticker_init (void)
+{
+  uint32_t v, w;
+  /*Start periodic timer */
+  systick_set_clocksource (STK_CSR_CLKSOURCE_AHB);
+  systick_set_reload (2288);
+  /* 72MHz / 2288 => 31.469531kHz (we wanted 31.46875) */
+  systick_interrupt_enable();
+  systick_counter_enable();
+
+  /*Calibrate the delay loop */
+  do {
+    scale--;
+    v = ticks;
+
+    while (v == ticks)
+      ;
+
+    delay_us (32);
+    w = ticks;
+    v++;
+    w -= v;
+  } while (w);
+}
+