pwm.c: disable when not needed

Timer/Counter 1 eats much power, especially with PLL clock. So let's
try to disable it when no PWM channel is active.

diff --git a/firmware/lights.h b/firmware/lights.h
index 68515097e6d7be62dd7962cebbd95d4e4d704c8a..0705dd12457965bef08b097268999bfe7bc90e50 100644 (file)
--- a/firmware/lights.h
+++ b/firmware/lights.h
@@ -42,6 +42,7 @@ void susp_pwm();
 void pwm_off(unsigned char n);
 void pwm_set(unsigned char n, uint16_t stride);
 void pwm_timer();
+void pwm_disable_if_not_needed();
 
 /* tmr.c */
 extern volatile uint16_t jiffies;

diff --git a/firmware/pwm.c b/firmware/pwm.c
index b47227375703f355198f724f63586cdba5937aa7..512268ccf03ee3b468ac87c56a05b193b6526382 100644 (file)
--- a/firmware/pwm.c
+++ b/firmware/pwm.c
@@ -1,5 +1,6 @@
 #include <avr/io.h>
 #include <avr/interrupt.h>
+#include <avr/power.h>
 #include <util/delay.h>
 #include <util/atomic.h>
 
@@ -13,6 +14,7 @@
 
 static uint16_t pwm[N_PWMLEDS];
 static volatile unsigned char step;
+static unsigned char channels_running, pll_enabled;
 
 static void enable_pll()
 {
@@ -24,6 +26,8 @@ static void enable_pll()
        while ((PLLCSR & _BV(PLOCK)) == 0)
                ;
        PLLCSR |= _BV(PCKE);
+
+       pll_enabled = 1;
 }
 
 void init_pwm()
@@ -31,12 +35,12 @@ 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
@@ -76,6 +80,7 @@ void pwm_off(unsigned char n)
 {
        ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
                pwm[n] = 0;
+               channels_running &= ~(1 << n);
 
                switch (n) {
                case 0: DDRB &= ~_BV(PB1); break;
@@ -119,6 +124,12 @@ void pwm_set(unsigned char n, uint16_t stride)
 
        ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
                pwm[n] = stride;
+               channels_running |= (1 << n);
+
+               if (!pll_enabled) {
+                       power_timer1_enable();
+                       enable_pll();
+               }
 
                pwm_update_hw(n);
 
@@ -142,3 +153,15 @@ 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();
+}
+

diff --git a/firmware/tmr.c b/firmware/tmr.c
index 2e61db859d2570b23b00ecd6eb5a460a3138ae16..7a31f19e486e2ab5edd720d36f5ea88255e273e5 100644 (file)
--- a/firmware/tmr.c
+++ b/firmware/tmr.c
@@ -22,6 +22,7 @@ ISR(WDT_vect) {
 
        timer_check_buttons();
        patterns_next_tick();
+       pwm_disable_if_not_needed();
        timer_start_slow_adcs();
 
        if ((jiffies & 0x7FF) == 0)