firmware source moved into subdirectory

[bike-lights.git] / firmware / pwm.c

diff --git a/firmware/pwm.c b/firmware/pwm.c
new file mode 100644 (file)
index 0000000..0c4f3d0
--- /dev/null
+++ b/firmware/pwm.c
@@ -0,0 +1,75 @@
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <util/delay.h>
+
+#include "lights.h"
+
+void init_pwm()
+{
+       /* Async clock */
+       PLLCSR = _BV(PLLE);
+
+       /* Synchronize to the phase lock */
+       _delay_ms(1);
+       while ((PLLCSR & _BV(PLOCK)) == 0)
+               ;
+       PLLCSR |= _BV(PCKE);
+
+       TCCR1C = _BV(COM1D0) | _BV(COM1D1) | _BV(PWM1D);
+       TCCR1A = _BV(COM1A0) | _BV(COM1A1) | _BV(COM1B0) | _BV(COM1B1) | _BV(PWM1A) | _BV(PWM1B);
+       TCCR1B = _BV(7)                         // PWM1X: PWM inversion mode
+               | _BV(CS10)                     // no clock prescaling
+               ;
+       TC1H = 0x01;
+       OCR1C = 0xFF;                           // TOP value
+
+       TC1H = 0x00;
+       OCR1D = 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
+}
+
+void pwm_on(unsigned char n)
+{
+       switch (n) {
+       case 0: DDRB |= _BV(PB1); break;
+       case 1: DDRB |= _BV(PB3); break;
+       case 2: DDRB |= _BV(PB5); break;
+       }
+}
+
+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;
+       }
+}
+
+void pwm_set(unsigned char n, unsigned char stride)
+{
+       TC1H = 0x00;
+       switch (n) {
+       case 0: OCR1A = stride; break;
+       case 1: OCR1B = stride; break;
+       case 2: OCR1D = stride; break;
+       }
+}
+
+#if 0
+static void inline pwm_handler()
+{
+       OCR1A = pwmval[0];
+       OCR1B = pwmval[1];
+       OCR1D = pwmval[2];
+       TIMSK &= ~_BV(TOIE1);
+}
+
+ISR(TIMER1_OVF_vect)
+{
+       pwm_handler();
+}
+#endif
+