Experimental step-up driver for chain of 5630 LEDs.

[tinyboard.git] / projects / step-up / pwm.c

diff --git a/projects/step-up/pwm.c b/projects/step-up/pwm.c
index b47227375703f355198f724f63586cdba5937aa7..b93a4fab8502039d73d811c69b96592725c5bad5 100644 (file)
--- a/projects/step-up/pwm.c
+++ b/projects/step-up/pwm.c
@@ -1,23 +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
+/*
+ * Single PWM channel on OC1B (pin PB4 of Tiny45).
+ * Counts from 0 to 0xFF, without OCR1C compare.
+ */
 
-static uint16_t pwm[N_PWMLEDS];
-static volatile unsigned char step;
+volatile unsigned char pwm_enabled;
 
-static void enable_pll()
+static void inline enable_pll()
 {
        /* Async clock */
-       PLLCSR = _BV(PLLE);
+       PLLCSR = _BV(PLLE) | _BV(LSM);
 
        /* Synchronize to the phase lock */
        _delay_us(100);
@@ -28,117 +27,48 @@ static void enable_pll()
 
 void init_pwm()
 {
-       int i;
+       pwm_enabled = 0;
+       power_timer1_enable();
 
-       step = 0;
+       TCCR1 = _BV(CTC1) | _BV(CS11);  // pll_clk/2
+       GTCCR = _BV(COM1B1) | _BV(PWM1B);
 
-       for (i = 0; i < N_PWMLEDS; i++)
-               pwm[i] = 0;
+       OCR1C = PWM_MAX;
+       OCR1B = 0;              // initial stride is 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
+       DDRB &= ~(_BV( PB4 ));
+       PORTB &= ~_BV(PB4); // 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;
+       DDRB &= ~(_BV( PB4 ));
+       PORTB &= ~(_BV( PB4 ));
+       TCCR1 = 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)
+void pwm_off()
 {
-       unsigned char hi, lo;
-       uint16_t stride = (pwm[n] + step) >> PWM_STEP_SHIFT;
+       OCR1B = 0;
+       DDRB &= ~_BV(PB4);
 
-       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;
-       }
+       PLLCSR &= ~(_BV(PLLE) | _BV(PCKE));
+       power_timer1_disable();
+       pwm_enabled = 0;
 }
 
-void pwm_set(unsigned char n, uint16_t stride)
+void pwm_set(uint8_t stride)
 {
-       if (stride > PWM_MAX)
-               stride = PWM_MAX;
-
-       ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
-               pwm[n] = stride;
-
-               pwm_update_hw(n);
+       OCR1B = stride;
 
-               switch(n) {
-               case 0: DDRB |= _BV(PB1); break;
-               case 1: DDRB |= _BV(PB3); break;
-               case 2: DDRB |= _BV(PB5); break;
-               }
+       if (!pwm_enabled) {
+               power_timer1_enable();
+               enable_pll();
+               DDRB |= _BV(PB4);
+               pwm_enabled = 1;
        }
 }
-
-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);
-}
-