/*
* Runs through a clock cycle. It sets the pulse generator to output a 36.6ns pulse or ~27.3MHz clock
*/
inline void TCK_Pump(void) {
set_length(0x0FFF);
__asm__ volatile ("nop");
trigger_pulse();
__asm__ volatile ("nop");
}
// --------------------------
// timerIsr() 50uS second interrupt ISR()
// Called every time the hardware timer 1 times out.
// --------------------------
void timerIsr()
{
trigger_pulse(); // Schedule the trigger pulses
distance_flasher(); // Flash the onboard LED distance indicator
}
void pit0_isr(void) {
// Set the direction bits. Todo: only do this at the start of a block.
STEPPER_PORT(DOR) = (STEPPER_PORT(DOR) & ~DIR_BIT) | (out_dir ? DIR_BIT : 0);
// hook for controller
if(step_hook_set)
if(step_hook())
return; // step_hook has done everything and asks us to quit here.
if(out_step)
trigger_pulse();
if(st.state == STATE_IDLE || st.state == STATE_ERROR){
// Disable this interrupt
PIT_TCTRL0 &= ~TEN;
PIT_TFLG0 = 1;
return;
}
if(st.state == STATE_SYNC){ // Done with a block, and done with outputting the last pulse
enter_sync_state();
// Allow this to retrigger next time
PIT_TFLG0 = 1;
return;
}
out_dir = out_step = 0;
// Execute step displacement profile by bresenham line algorithm
if(current_block->length < 0){
out_dir = 1;
st.counter -= current_block->length;
}else{
st.counter += current_block->length;
}
if (st.counter > 0) {
out_step = 1;
st.counter -= st.event_count;
}
st.step_events_completed++; // Iterate step events
if(current_block->total_length <= st.step_events_completed){
// Allow this to trigger once more, to pulse out the last step
current_block = NULL;
st.state = STATE_SYNC;
PIT_TFLG0 = 1;
return;
}
// The trapezoid generator always checks step event location to ensure de/ac-celerations are
// executed and terminated at exactly the right time. This helps prevent over/under-shooting
// the target position and speed.
// NOTE: By increasing the ACCELERATION_TICKS_PER_SECOND in config.h, the resolution of the
// discrete velocity changes increase and accuracy can increase as well to a point. Numerical
// round-off errors can effect this, if set too high. This is important to note if a user has
// very high acceleration and/or feedrate requirements for their machine.
if (st.step_events_completed < current_block->stop_accelerating) {
// Iterate cycle counter and check if speeds need to be increased.
if ( iterate_trapezoid_cycle_counter() ) {
st.trapezoid_adjusted_rate += current_block->acceleration;
if (st.trapezoid_adjusted_rate >= current_block->nominal_rate) {
// Reached nominal rate a little early. Cruise at nominal rate until decelerate_after.
st.trapezoid_adjusted_rate = current_block->nominal_rate;
}
set_step_events_per_minute(st.trapezoid_adjusted_rate);
}
} else if (st.step_events_completed >= current_block->start_decelerating) {
// Reset trapezoid tick cycle counter to make sure that the deceleration is performed the
// same every time. Reset to CYCLES_PER_ACCELERATION_TICK/2 to follow the midpoint rule for
// an accurate approximation of the deceleration curve. For triangle profiles, down count
// from current cycle counter to ensure exact deceleration curve.
if (st.step_events_completed == current_block->start_decelerating) {
if (st.trapezoid_adjusted_rate == current_block->nominal_rate) {
st.trapezoid_tick_cycle_counter = CYCLES_PER_ACCELERATION_TICK/2; // Trapezoid profile
} else {
st.trapezoid_tick_cycle_counter = CYCLES_PER_ACCELERATION_TICK-st.trapezoid_tick_cycle_counter; // Triangle profile
}
} else {
// Iterate cycle counter and check if speeds need to be reduced.
if ( iterate_trapezoid_cycle_counter() ) {
// NOTE: We will only do a full speed reduction if the result is more than the minimum safe
// rate, initialized in trapezoid reset as 1.5 x rate_delta. Otherwise, reduce the speed by
// half increments until finished. The half increments are guaranteed not to exceed the
// CNC acceleration limits, because they will never be greater than rate_delta. This catches
// small errors that might leave steps hanging after the last trapezoid tick or a very slow
// step rate at the end of a full stop deceleration in certain situations. The half rate
// reductions should only be called once or twice per block and create a nice smooth
// end deceleration.
if (st.trapezoid_adjusted_rate > st.min_safe_rate) {
st.trapezoid_adjusted_rate -= current_block->acceleration;
} else {
st.trapezoid_adjusted_rate >>= 1; // Bit shift divide by 2
}
if (st.trapezoid_adjusted_rate < current_block->final_rate) {
// Reached final rate a little early. Cruise to end of block at final rate.
st.trapezoid_adjusted_rate = current_block->final_rate;
}
set_step_events_per_minute(st.trapezoid_adjusted_rate);
}
}
} else {
// No accelerations. Make sure we cruise exactly at the nominal rate.
if (st.trapezoid_adjusted_rate != current_block->nominal_rate) {