X-Git-Url: https://www.fi.muni.cz/~kas/git//home/kas/public_html/git/?p=tinyboard.git;a=blobdiff_plain;f=projects%2Fstep-up%2Fpwm.c;fp=projects%2Fstep-up%2Fpwm.c;h=b47227375703f355198f724f63586cdba5937aa7;hp=0000000000000000000000000000000000000000;hb=edebb613b2f867d4f8473747744f329cb30e38fe;hpb=5aa70c4eca2337027c5ca5ece45c0031b95026ef

diff --git a/projects/step-up/pwm.c b/projects/step-up/pwm.c
new file mode 100644
index 0000000..b472273
--- /dev/null
+++ b/projects/step-up/pwm.c
@@ -0,0 +1,144 @@
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <util/delay.h>
+#include <util/atomic.h>
+
+#include "lights.h"
+
+#define PWM_STEP_SHIFT 2 /* sub-LSB precision */
+#define PWM_TOP (((PWM_MAX) + (4 << (PWM_STEP_SHIFT))) >> (PWM_STEP_SHIFT))
+#if PWM_TOP > 0x3FF
+#error PWM_TOP too high
+#endif
+
+static uint16_t pwm[N_PWMLEDS];
+static volatile unsigned char step;
+
+static void enable_pll()
+{
+	/* Async clock */
+	PLLCSR = _BV(PLLE);
+
+	/* Synchronize to the phase lock */
+	_delay_us(100);
+	while ((PLLCSR & _BV(PLOCK)) == 0)
+		;
+	PLLCSR |= _BV(PCKE);
+}
+
+void init_pwm()
+{
+	int i;
+
+	step = 0;
+
+	for (i = 0; i < N_PWMLEDS; i++)
+		pwm[i] = 0;
+
+	enable_pll();
+
+	// PWM channel D is inverted, ...
+	TCCR1C = _BV(COM1D1) | _BV(COM1D0) | _BV(PWM1D);
+	// PWM channels A and B are not
+	TCCR1A = _BV(COM1A1) | _BV(COM1B1) | _BV(PWM1A) | _BV(PWM1B);
+	TCCR1D = 0;
+	TCCR1B = _BV(CS10); 			// no clock prescaling
+
+	TC1H = PWM_TOP >> 8;
+	OCR1C = PWM_TOP & 0xFF;				// TOP value
+
+	TC1H = PWM_TOP >> 8;		// PWM3 is inverted
+	OCR1D = PWM_TOP & 0xFF;
+
+	TC1H = 0x00;
+	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 susp_pwm()
+{
+	unsigned char i;
+
+	for (i = 0; i < N_PWMLEDS; i++)
+		pwm[i] = 0;
+
+	DDRB &= ~(_BV( PB1 ) | _BV( PB3 ) | _BV( PB5 ));
+	TCCR1D = TCCR1C = TCCR1B = TCCR1A = 0;
+	TIMSK = 0;
+	TIFR = 0;
+
+	PLLCSR &= ~(_BV(PLLE) | _BV(PCKE));
+}
+
+void pwm_off(unsigned char n)
+{
+	ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
+		pwm[n] = 0;
+
+		switch (n) {
+		case 0: DDRB &= ~_BV(PB1); break;
+		case 1: DDRB &= ~_BV(PB3); break;
+		case 2: DDRB &= ~_BV(PB5); break;
+		}
+	}
+}
+
+static void pwm_update_hw(unsigned char n)
+{
+	unsigned char hi, lo;
+	uint16_t stride = (pwm[n] + step) >> PWM_STEP_SHIFT;
+
+	if (n == 2)
+		stride = PWM_TOP - stride;
+
+	hi = stride >> 8;
+	lo = stride & 0xFF;
+
+	switch (n) {
+	case 0:
+		TC1H = hi;
+		OCR1A = lo;
+		break;
+	case 1:
+		TC1H = hi;
+		OCR1B = lo;
+		break;
+	case 2:
+		TC1H = hi;
+		OCR1D = lo;
+		break;
+	}
+}
+
+void pwm_set(unsigned char n, uint16_t stride)
+{
+	if (stride > PWM_MAX)
+		stride = PWM_MAX;
+
+	ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
+		pwm[n] = stride;
+
+		pwm_update_hw(n);
+
+		switch(n) {
+		case 0: DDRB |= _BV(PB1); break;
+		case 1: DDRB |= _BV(PB3); break;
+		case 2: DDRB |= _BV(PB5); break;
+		}
+	}
+}
+
+void pwm_timer()
+{
+	unsigned char i;
+
+	if (++step >= (1 << PWM_STEP_SHIFT))
+		step = 0;
+
+	for (i = 0; i < N_PWMLEDS; i++)
+		if (pwm[i])
+			pwm_update_hw(i);
+}
+