X-Git-Url: https://www.fi.muni.cz/~kas/git//home/kas/public_html/git/?p=bike-lights.git;a=blobdiff_plain;f=firmware%2Fpwm.c;fp=firmware%2Fpwm.c;h=0c4f3d081a5b78ddbc9f2493255a17b0da6496bf;hp=0000000000000000000000000000000000000000;hb=f956c1fa7f47b0e8b8afe323c2eff1b6c2607c2a;hpb=f7cba12a75f10da7267c2e4d4488bb5ccddbb9d9

diff --git a/firmware/pwm.c b/firmware/pwm.c
new file mode 100644
index 0000000..0c4f3d0
--- /dev/null
+++ b/firmware/pwm.c
@@ -0,0 +1,75 @@
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <util/delay.h>
+
+#include "lights.h"
+
+void init_pwm()
+{
+	/* Async clock */
+	PLLCSR = _BV(PLLE);
+
+	/* Synchronize to the phase lock */
+	_delay_ms(1);
+	while ((PLLCSR & _BV(PLOCK)) == 0)
+		;
+	PLLCSR |= _BV(PCKE);
+
+	TCCR1C = _BV(COM1D0) | _BV(COM1D1) | _BV(PWM1D);
+	TCCR1A = _BV(COM1A0) | _BV(COM1A1) | _BV(COM1B0) | _BV(COM1B1) | _BV(PWM1A) | _BV(PWM1B);
+	TCCR1B = _BV(7)				// PWM1X: PWM inversion mode
+		| _BV(CS10) 			// no clock prescaling
+		;
+	TC1H = 0x01;
+	OCR1C = 0xFF;				// TOP value
+
+	TC1H = 0x00;
+	OCR1D = OCR1B = OCR1A = 0;		// initial stride is 0
+
+	DDRB  &= ~(_BV( PB1 ) | _BV( PB3 ) | _BV( PB5 )); // tristate it
+	PORTB &= ~(_BV( PB1 ) | _BV( PB3 ) | _BV( PB5 )); // set to zero
+}
+
+void pwm_on(unsigned char n)
+{
+	switch (n) {
+	case 0: DDRB |= _BV(PB1); break;
+	case 1: DDRB |= _BV(PB3); break;
+	case 2: DDRB |= _BV(PB5); break;
+	}
+}
+
+void pwm_off(unsigned char n)
+{
+	switch (n) {
+	case 0: DDRB &= ~_BV(PB1); break;
+	case 1: DDRB &= ~_BV(PB3); break;
+	case 2: DDRB &= ~_BV(PB5); break;
+	}
+}
+
+void pwm_set(unsigned char n, unsigned char stride)
+{
+	TC1H = 0x00;
+	switch (n) {
+	case 0: OCR1A = stride; break;
+	case 1: OCR1B = stride; break;
+	case 2: OCR1D = stride; break;
+	}
+}
+
+#if 0
+static void inline pwm_handler()
+{
+	OCR1A = pwmval[0];
+	OCR1B = pwmval[1];
+	OCR1D = pwmval[2];
+	TIMSK &= ~_BV(TOIE1);
+}
+
+ISR(TIMER1_OVF_vect)
+{
+	pwm_handler();
+}
+#endif
+