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#if 0
volatile uint16_t stepcounter;
// Stepper interrupt. Will step the primary axis each time it's executed and
// use DDA to step the secondary axes.
ISR(TIMER1_COMPA_vect)
{
// We will always step the primary axis, but we count it anyway
// so we don't have to calculate which one is primary.
for (uint8_t i=0;i<3;i++) {
if (CAN_STEP(i)) {
counter[i] += delta_steps[i];
if (counter[i] > 0) {
counter[i] -= max_delta;
do_step(STEP_PIN(i));
// Update current position
if (direction[i]) current_steps[i]++;
else current_steps[i]--;
}
}
}
stepcounter--;
if (stepcounter == 0) {
// stop interrupt
TCCR1B &= ~(_BV(CS12) | _BV(CS11) | _BV(CS10));
// signal main loop to dequeue next command
}
}
void startLineSegment(Command cmd)
{
uint16_t abs_delta_steps[3];
bool direction[3];
uint32_t maxstepdelay_us;
// FIXME: Decode cmd into above variables
max_delta = max(delta_steps[0], delta_steps[1]);
max_delta = max(delta_steps[2], max_delta);
int16_t counter[3];
counter[0] = -max_delta/2;
counter[1] = -max_delta/2;
counter[2] = -max_delta/2;
stepcounter = max_delta;
// init interrupt parameters
/*
Timer resolution notes (@16MHz)
Prescaler 16-bits timeout (us)
1 4096
8 32768
64 256K
256 1024K
1024 4096K
*/
// CTC mode
TCCR1A &= ~(_BV(WGM11) | _BV(WGM10));
TCCR1B &= ~_BV(WGM13);
TCCR1B |= _BV(CTC1);
// Calculate prescaler
uint16_t prescaler;
uint8_t prescaleflags = 0;
if (maxstepdelay_us < 4096) {
prescaleflags = _BV(CS10); // 1
prescalebits = 0;
}
else if (maxstepdelay_us < 32768) {
prescaleflags = _BV(CS11); // 8
prescalebits = 3;
}
else if (maxstepdelay_us < 256*1024) {
prescaleflags = _BV(CS11) | _BV(CS10); // 64
prescalebits = 6;
}
else {
prescaleflags = _BV(CS12) | _BV(CS10); // 256
prescalebits = 8;
}
// Init CTC and timer values
uint16_t topval = (maxstepdelay_us * (F_CPU/1000000)) >> (prescalebits + 1) - 1;
OCR1A = topval;
TCNT1 = 0;
// start interrupt
TCCR1B &= ~(_BV(CS12) | _BV(CS11) | _BV(CS10));
TCCR1B |= prescaleflags;
}
#endif
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