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=8c95619a8f06ec423abce77a25f0a32f59f55258;hb=65c3ad96cf307c3b77b36e6f6a2af5201c213a3c;hpb=43b162ab0d886c7f75a9e8702052ab90ae462189

diff --git a/firmware/pwm.c b/firmware/pwm.c
index 8c95619..27c8d0d 100644
--- a/firmware/pwm.c
+++ b/firmware/pwm.c
@@ -1,11 +1,22 @@
 #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_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
+
+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()
 {
@@ -17,6 +28,8 @@ static void enable_pll()
 	while ((PLLCSR & _BV(PLOCK)) == 0)
 		;
 	PLLCSR |= _BV(PCKE);
+
+	pll_enabled = 1;
 }
 
 void init_pwm()
@@ -24,12 +37,12 @@ void init_pwm()
 	int i;
 
 	step = 0;
+	channels_running = 0;
+	pll_enabled = 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
@@ -37,11 +50,11 @@ void init_pwm()
 	TCCR1D = 0;
 	TCCR1B = _BV(CS10); 			// no clock prescaling
 
-	TC1H = PWM_MAX >> 8;
-	OCR1C = PWM_MAX & 0xFF;				// TOP value
+	TC1H = PWM_TOP >> 8;
+	OCR1C = PWM_TOP & 0xFF;				// TOP value
 
-	TC1H = PWM_MAX >> 8;		// PWM3 is inverted
-	OCR1D = PWM_MAX & 0xFF;
+	TC1H = PWM_TOP >> 8;		// PWM3 is inverted
+	OCR1D = PWM_TOP & 0xFF;
 
 	TC1H = 0x00;
 	OCR1B = OCR1A = 0;		// initial stride is 0
@@ -67,12 +80,15 @@ void susp_pwm()
 
 void pwm_off(unsigned char n)
 {
-	pwm[n] = 0;
-
-	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;
+		}
 	}
 }
 
@@ -82,7 +98,7 @@ static void pwm_update_hw(unsigned char n)
 	uint16_t stride = (pwm[n] + step) >> PWM_STEP_SHIFT;
 
 	if (n == 2)
-		stride = PWM_MAX - stride;
+		stride = PWM_TOP - stride;
 
 	hi = stride >> 8;
 	lo = stride & 0xFF;
@@ -91,28 +107,40 @@ static void pwm_update_hw(unsigned char n)
 	case 0:
 		TC1H = hi;
 		OCR1A = lo;
-		DDRB |= _BV(PB1);
 		break;
 	case 1:
 		TC1H = hi;
 		OCR1B = lo;
-		DDRB |= _BV(PB3);
 		break;
 	case 2:
 		TC1H = hi;
 		OCR1D = lo;
-		DDRB |= _BV(PB5);
 		break;
 	}
 }
 
 void pwm_set(unsigned char n, uint16_t stride)
 {
-	if (((stride + (1 << PWM_STEP_SHIFT)) >> PWM_STEP_SHIFT) >= PWM_MAX)
-		stride = PWM_MAX << PWM_STEP_SHIFT;
+	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[n] = stride;
-	pwm_update_hw(n);
+		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()
@@ -127,3 +155,15 @@ void pwm_timer()
 			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();
+}
+