working decoding

1 files changed, 79 insertions, 0 deletions

diff --git a/app/ticker.c b/app/ticker.c
new file mode 100644
index 0000000..af91d14
--- /dev/null
+++ b/app/ticker.c
@@ -0,0 +1,79 @@
+#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++;
+
+  slow++;
+
+  if (slow < 1000)
+    return;
+
+  slow = 0;
+
+  led_slow_tick();
+  abs_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 / 168000 -> 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;
+
+}