On 08/26/14 11:31, Thomas D. Dean wrote:
I found a sort-of solution. I still have a 1 usec glitch at the end of
the positive group of cycles but not at the inverted group of cycles.
The manual says the change of COM bits is effected at the next compare
match. On the logic analyzer, it appears this happens at bottom.
Any ideas?
Tom Dean
/*
* oc-pwm.c - use output compare to generate PWD without interrupts
*/
/*
* -- from NG02 motor.c -------
* TCCR1A = _BV(WGM10);
* TCCR1B = _BV(WGM12) | _BV(CS11);
* TIMSK |= _BV(TOIE1) | _BV(OCIE1B) | _BV(OCIE1A);
*
* WGM mode 5 fast PWM 8-bit, CLKio/8, port normal i/o operation, now PWM
* ----------------------------
* if FWD clear R PWM pin on match ==> WGM 5, COM 2
* clear L PWM pin on match ==> WGM 5, COM 2
* set R PWM pin on TOVF ==> WGM 5, COM 2
* set L PWM pin on TOVF ==> WGM 5, COM 2
*
* if REV set R PWM pin on match ==> WGM 5, COM 3
* set L PWM pin on match ==> WGM 5, COM 3
* clear R PWM pin on TOVF ==> WGM 5, COM 3
* clear L PWM pin on TOVF ==> WGM 5, COM 3
*
* Use OC1A for left motor PWM
* OC1B for right motor PWM
*/
#include <avr/io.h> /* ports and registers */
#include <trace.h>
void motor_init(void);
void both_motor_fwd(void);
void both_motor_rev(void);
void initialize(void);
void initialize() {
TRACE_PORT_DDR = ALL_OUT;
TRACE_PORT = 0;
TCCR0 = _BV(CS00);
}
void both_motor_stop() {
if ((TIFR & _BV(TOV1)) == 0) {
while ((TIFR & _BV(TOV1)) == 0) ;
TIFR |= _BV(TOV1);
}
TRACE_ON(3);
TCCR1A = 0;
TCCR1B = 0;
OCR1A = 255;
OCR1B = 255;
TIFR |= _BV(TOV1);
TRACE_OFF(3);
}
void both_motor_fwd() {
OCR1A = 80;
OCR1B = 160;
TCCR1A = _BV(COM1A1) | _BV(COM1B1) | _BV(WGM10);
TCCR1B = _BV(WGM12) | _BV(CS11);
TCNT1 = 0;
TIFR |= _BV(TOV1);
}
void both_motor_rev() {
OCR1A = 80;
OCR1B = 160;
TCCR1A = _BV(COM1A1) | _BV(COM1A0) | _BV(COM1B1) | _BV(COM1B0) | _BV(WGM10);
TCCR1B = _BV(WGM12) | _BV(CS11);
TCNT1 = 0;
TIFR |= _BV(TOV1);
}
void motor_init() {
DDRB |= _BV(PB6) | _BV(PB5);
OCR1A = 80;
OCR1B = 0;
/* WGM mode 5, clk/8 */
TCCR1A = _BV(COM1A1) | _BV(COM1B1) | _BV(WGM10);
TCCR1B = _BV(WGM12) | _BV(CS11);
TCNT1 = 0;
TIFR |= _BV(TOV1);
}
int main() {
initialize();
motor_init();
int count;
TIFR |= _BV(TOV1);
while (1) {
TRACE_ON(0);
TRACE_ON(1);
count = 5;
do {
while ((TIFR & _BV(TOV1)) == 0) ;
TIFR |= _BV(TOV1);
} while (--count);
TRACE_OFF(1);
/* stop motors */
both_motor_stop();
/* wait 16 used */
TCNT0 = 0;
TIFR |= _BV(TOV0);
while ((TIFR & _BV(TOV0)) == 0) ;
/* start reverse */
both_motor_rev();
TIFR |= _BV(TOV1);
TRACE_ON(2);
count = 5;
do {
while ((TIFR & _BV(TOV1)) == 0) ;
TIFR |= _BV(TOV1);
} while (--count);
TRACE_OFF(2);
/* stop motors */
both_motor_stop();
/* wait 16 used */
TCNT0 = 0;
TIFR |= _BV(TOV0);
while ((TIFR & _BV(TOV0)) == 0) ;
/* start fwd */
both_motor_fwd();
TRACE_OFF(0);
}
return 0;
}
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