Commit 899ce952 authored by Jan Kasprzak's avatar Jan Kasprzak
Browse files

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.
parent 280768d8
......@@ -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);
......
......@@ -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;
}
}
}
......
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