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;h=27c8d0d0187d6e9a3f3e2a78448aefa7f0438843;hp=2df2e6bb8b9abe762c1bb6208a13e6a4dde4cd7c;hb=65c3ad96cf307c3b77b36e6f6a2af5201c213a3c;hpb=ddc8f4be4d90e7e709832b5135b2e7e4631b1554

diff --git a/firmware/pwm.c b/firmware/pwm.c
index 2df2e6b..27c8d0d 100644
--- a/firmware/pwm.c
+++ b/firmware/pwm.c
@@ -1,33 +1,60 @@
 #include <avr/io.h>
 #include <avr/interrupt.h>
+#include <avr/power.h>
 #include <util/delay.h>
+#include <util/atomic.h>
 
 #include "lights.h"
 
-#define PWM_MAX 0x1FF
+#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
 
-void init_pwm()
+volatile unsigned char channels_running;
+
+static uint16_t pwm[N_PWMLEDS];
+static volatile unsigned char step;
+static unsigned char pll_enabled;
+
+static void enable_pll()
 {
 	/* Async clock */
 	PLLCSR = _BV(PLLE);
 
 	/* Synchronize to the phase lock */
-	_delay_ms(1);
+	_delay_us(100);
 	while ((PLLCSR & _BV(PLOCK)) == 0)
 		;
 	PLLCSR |= _BV(PCKE);
 
+	pll_enabled = 1;
+}
+
+void init_pwm()
+{
+	int i;
+
+	step = 0;
+	channels_running = 0;
+	pll_enabled = 0;
+
+	for (i = 0; i < N_PWMLEDS; i++)
+		pwm[i] = 0;
+
 	// 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_MAX >> 8;
-	OCR1C = PWM_MAX & 0xFF;				// TOP value
 
-	TC1H = PWM_MAX >> 8;
-	OCR1D = PWM_MAX & 0xFF;
+	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
@@ -36,54 +63,107 @@ void init_pwm()
 	PORTB &= ~(_BV( PB1 ) | _BV( PB3 ) | _BV( PB5 )); // set to zero
 }
 
-void pwm_on(unsigned char n)
+void susp_pwm()
 {
-	switch (n) {
-	case 0: DDRB |= _BV(PB1); break;
-	case 1: DDRB |= _BV(PB3); break;
-	case 2: DDRB |= _BV(PB5); break;
-	}
+	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)
 {
-	switch (n) {
-	case 0: DDRB &= ~_BV(PB1); break;
-	case 1: DDRB &= ~_BV(PB3); break;
-	case 2: DDRB &= ~_BV(PB5); break;
+	ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
+		pwm[n] = 0;
+		channels_running &= ~(1 << 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)
+static void pwm_update_hw(unsigned char n)
 {
-	TC1H = 0x00;
+	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: OCR1A = stride; break;
-	case 1: OCR1B = stride; break;
-	case 2: {
-			uint16_t s16 = PWM_MAX - (uint16_t)stride;
-			volatile unsigned char hi, lo;
-			hi = s16 >> 8;
-			lo = s16 & 0xFF;
-			TC1H = hi;
-			OCR1D = lo;
-		}
+	case 0:
+		TC1H = hi;
+		OCR1A = lo;
+		break;
+	case 1:
+		TC1H = hi;
+		OCR1B = lo;
+		break;
+	case 2:
+		TC1H = hi;
+		OCR1D = lo;
 		break;
 	}
 }
 
-#if 0
-static void inline pwm_handler()
+void pwm_set(unsigned char n, uint16_t stride)
 {
-	OCR1A = pwmval[0];
-	OCR1B = pwmval[1];
-	OCR1D = pwmval[2];
-	TIMSK &= ~_BV(TOIE1);
+	if (stride > PWM_MAX)
+		stride = PWM_MAX;
+
+	ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
+		pwm[n] = stride;
+		channels_running |= (1 << n);
+
+		if (!pll_enabled) {
+			power_timer1_enable();
+			enable_pll();
+		}
+
+		pwm_update_hw(n);
+
+		switch(n) {
+		case 0: DDRB |= _BV(PB1); break;
+		case 1: DDRB |= _BV(PB3); break;
+		case 2: DDRB |= _BV(PB5); break;
+		}
+	}
 }
 
-ISR(TIMER1_OVF_vect)
+void pwm_timer()
 {
-	pwm_handler();
+	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);
+}
+
+void pwm_disable_if_not_needed()
+{
+	if (channels_running)
+		return;
+
+	pll_enabled = 0;
+	DDRB &= ~(_BV(PB1) | _BV(PB3) | _BV(PB5));
+	PLLCSR &= ~(_BV(PLLE) | _BV(PCKE));
+
+	power_timer1_disable();
 }
-#endif