X-Git-Url: http://git.tdb.fi/?a=blobdiff_plain;f=common%2Ftimer.c;fp=common%2Ftimer.c;h=99625f8c2abd4b6df8ca0dd552b760499d09bf6e;hb=9c37d18b9c70fdb70dfec453398c4649e9e57586;hp=0000000000000000000000000000000000000000;hpb=49b6b6ad84ec47b4f9eb9ef131975cc5b72372a2;p=model-railway-devices.git

diff --git a/common/timer.c b/common/timer.c
new file mode 100644
index 0000000..99625f8
--- /dev/null
+++ b/common/timer.c
@@ -0,0 +1,101 @@
+#include <avr/io.h>
+#include "timer.h"
+
+#define BIT(n) (1<<(n))
+
+static void timer_start(uint8_t num, uint32_t period)
+{
+	uint8_t cs;
+
+	if(num==0)
+	{
+		if(period<0x100)
+		{
+			cs = BIT(CS00);
+		}
+		else if(period<0x800)
+		{
+			cs = BIT(CS01);
+			period /= 8;
+		}
+		else if(period<0x4000)
+		{
+			cs = BIT(CS01) | BIT(CS00);
+			period /= 64;
+		}
+		else if(period<0x10000)
+		{
+			cs = BIT(CS02);
+			period /= 256;
+		}
+		else
+		{
+			cs = BIT(CS02) | BIT(CS00);
+			period /= 1024;
+			if(period>0xFF)
+				period = 0xFF;
+		}
+		TCCR0A = BIT(WGM01);
+		TCCR0B = cs;
+		OCR0A = period;
+		TIMSK0 = BIT(OCIE0A);
+	}
+	if(num==1)
+	{
+		if(period<0x10000)
+		{
+			cs = BIT(CS10);
+		}
+		else if(period<0x80000)
+		{
+			cs = BIT(CS11);
+			period /= 8;
+		}
+		else if(period<0x400000)
+		{
+			cs = BIT(CS11) | BIT(CS10);
+			period /= 64;
+		}
+		else if(period<0x1000000)
+		{
+			cs = BIT(CS12);
+			period /= 256;
+		}
+		else
+		{
+			cs = BIT(CS12) | BIT(CS10);
+			period /= 1024;
+			if(period>0xFFFF)
+				period = 0xFFFF;
+		}
+		TCCR1A = 0;
+		TCCR1B = BIT(WGM12) | cs;
+		OCR1AH = period>>8;
+		OCR1AL = period;
+		TIMSK1 = BIT(OCIE1A);
+	}
+}
+
+void timer_start_hz(uint8_t num, uint32_t freq_p, uint8_t freq_q)
+{
+	timer_start(num, F_CPU*freq_q/freq_p);
+}
+
+void timer_start_us(uint8_t num, uint32_t us)
+{
+	timer_start(num, F_CPU/1000000*us);
+}
+
+void timer_stop(uint8_t num)
+{
+	if(num==0)
+	{
+		TCCR0B = 0;
+		TIMSK0 = 0;
+	}
+	else if(num==1)
+	{
+		TCCR1B = 0;
+		TIMSK1 = 0;
+	}
+}