pwm.c: modified for ATtiny45/step-up

So far two PWM channels OC1A/OC1B with sub-LSB resolution possible
(but unused yet) using timer IRQ.

TODO: get rid of OCR1C register and let it count to 255.

diff --git a/projects/step-up/lights.h b/projects/step-up/lights.h
index 772613ac513b34943450c4182a64302f545d5f6e..986ffcb7ec935eac3ae6faef0881b26d844e0cb7 100644 (file)
--- a/projects/step-up/lights.h
+++ b/projects/step-up/lights.h
@@ -4,7 +4,7 @@
 #define TESTING_FW 1
 
 #define N_LEDS 7
-#define N_PWMLEDS 3
+#define N_PWMLEDS 2
 #define N_PWMLED_MODES 4
 
 #define N_BUTTONS 2
@@ -36,7 +36,7 @@ void timer_start_slow_adcs();
  * A/D converter frequency (125 kHz). Note that this is not the Top
  * value of T/C 1, it is shifted by PWM_STEP_SHIFT as described in pwm.c
  */
-#define PWM_MAX 0x780
+#define PWM_MAX 0x340
 void init_pwm();
 void susp_pwm();
 void pwm_off(unsigned char n);

diff --git a/projects/step-up/pwm.c b/projects/step-up/pwm.c
index b47227375703f355198f724f63586cdba5937aa7..85d6c6820c4e3768a12016ceae8f75ec021ee2c4 100644 (file)
--- a/projects/step-up/pwm.c
+++ b/projects/step-up/pwm.c
@@ -7,7 +7,7 @@
 
 #define PWM_STEP_SHIFT 2 /* sub-LSB precision */
 #define PWM_TOP (((PWM_MAX) + (4 << (PWM_STEP_SHIFT))) >> (PWM_STEP_SHIFT))
-#if PWM_TOP > 0x3FF
+#if PWM_TOP > 0x0FF
 #error PWM_TOP too high
 #endif
 
@@ -37,26 +37,17 @@ void init_pwm()
 
        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
+       TCCR1 = _BV(CTC1) | _BV(CS10);  // no clock prescaling
+       GTCCR = _BV(COM1A1) | _BV(COM1B1) | _BV(PWM1A) | _BV(PWM1B);
 
-       TC1H = PWM_TOP >> 8;
-       OCR1C = PWM_TOP & 0xFF;                         // TOP value
+       OCR1C = PWM_TOP;
+       OCR1A = OCR1B = 0;              // initial stride is 0
 
-       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( PB1 ) | _BV( PB4 )); // tristate it
+       PORTB &= ~(_BV( PB1 ) | _BV( PB4 )); // set to zero
 }
 
+#if 0
 void susp_pwm()
 {
        unsigned char i;
@@ -71,6 +62,7 @@ void susp_pwm()
 
        PLLCSR &= ~(_BV(PLLE) | _BV(PCKE));
 }
+#endif
 
 void pwm_off(unsigned char n)
 {
@@ -79,35 +71,21 @@ 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;
+               case 1: DDRB &= ~_BV(PB4); break;
                }
        }
 }
 
 static void pwm_update_hw(unsigned char n)
 {
-       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:
-               TC1H = hi;
-               OCR1A = lo;
+               OCR1A = stride;
                break;
        case 1:
-               TC1H = hi;
-               OCR1B = lo;
-               break;
-       case 2:
-               TC1H = hi;
-               OCR1D = lo;
+               OCR1B = stride;
                break;
        }
 }
@@ -124,8 +102,7 @@ void pwm_set(unsigned char n, uint16_t stride)
 
                switch(n) {
                case 0: DDRB |= _BV(PB1); break;
-               case 1: DDRB |= _BV(PB3); break;
-               case 2: DDRB |= _BV(PB5); break;
+               case 1: DDRB |= _BV(PB4); break;
                }
        }
 }