From d85f3aeeeefd6926fe71ec8e066adb74f62dc1cc Mon Sep 17 00:00:00 2001
From: fishsoupisgood <github@madingley.org>
Date: Sat, 13 Jun 2020 21:05:45 +0100
Subject: fish

---
 app/ticker.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 app/ticker.c

(limited to 'app/ticker.c')

diff --git a/app/ticker.c b/app/ticker.c
new file mode 100644
index 0000000..c0008fe
--- /dev/null
+++ b/app/ticker.c
@@ -0,0 +1,72 @@
+#include "project.h"
+
+
+static volatile uint32_t ticks;
+static volatile uint32_t delay_ms_count;
+static uint32_t scale = 7;
+
+void
+delay_us (uint32_t d)
+{
+  d *= scale;
+
+  while (d--)
+    __asm__ ("nop");
+}
+
+
+void
+sys_tick_handler (void)
+{
+  if (delay_ms_count)
+    delay_ms_count--;
+
+
+  led_tick ();
+  oled_refresh_wdt ();
+
+  ticks++;
+}
+
+
+void
+delay_ms (uint32_t d)
+{
+  delay_ms_count = d;
+  while (delay_ms_count);
+}
+
+
+void
+ticker_init (void)
+{
+  uint32_t v, w;
+
+  /*Start periodic timer */
+
+  systick_set_clocksource (STK_CSR_CLKSOURCE_AHB_DIV8);
+  /* 72MHz / 8 = > 9Mhz */
+  systick_set_reload (9000);
+  /* 9MHz / 9000 => 1kHz */
+  systick_interrupt_enable ();
+  systick_counter_enable ();
+
+  /*Calibrate the delay loop */
+
+
+  do
+    {
+      scale--;
+      v = ticks;
+
+      while (v == ticks);
+
+      delay_us (1000);
+      w = ticks;
+      v++;
+      w -= v;
+    }
+  while (w);
+
+
+}
-- 
cgit v1.2.3