#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 > 0x0FF
-#error PWM_TOP too high
-#endif
-
-static uint16_t pwm[N_PWMLEDS];
-static volatile unsigned char step;
+/*
+ * Single PWM channel on OC1B (pin PB4 of Tiny45).
+ * Counts from 0 to 0xFF, without OCR1C compare.
+ */
-static void enable_pll()
+static void inline enable_pll()
{
/* Async clock */
PLLCSR = _BV(PLLE);
void init_pwm()
{
- int i;
-
- step = 0;
-
- for (i = 0; i < N_PWMLEDS; i++)
- pwm[i] = 0;
+ power_timer1_enable();
enable_pll();
TCCR1 = _BV(CTC1) | _BV(CS10); // no clock prescaling
- GTCCR = _BV(COM1A1) | _BV(COM1B1) | _BV(PWM1A) | _BV(PWM1B);
+ GTCCR = _BV(COM1B1) | _BV(PWM1B);
- OCR1C = PWM_TOP;
- OCR1A = OCR1B = 0; // initial stride is 0
+ OCR1C = PWM_MAX;
+ OCR1B = 0; // initial stride is 0
- DDRB &= ~(_BV( PB1 ) | _BV( PB4 )); // tristate it
- PORTB &= ~(_BV( PB1 ) | _BV( PB4 )); // set to zero
+ DDRB &= ~_BV(PB4); // tristate it
+ PORTB &= ~_BV(PB4); // set to zero
}
#if 0
}
#endif
-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(PB4); break;
- }
- }
-}
-
-static void pwm_update_hw(unsigned char n)
-{
- uint16_t stride = (pwm[n] + step) >> PWM_STEP_SHIFT;
-
- switch (n) {
- case 0:
- OCR1A = stride;
- break;
- case 1:
- OCR1B = stride;
- break;
- }
-}
-
-void pwm_set(unsigned char n, uint16_t stride)
+void pwm_off()
{
- 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(PB4); break;
- }
- }
+ OCR1B = 0;
+ DDRB &= ~_BV(PB4);
}
-void pwm_timer()
+void pwm_set(uint8_t stride)
{
- 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);
+ OCR1B = stride;
+ DDRB |= _BV(PB4);
}
-