Step pulse off timing

[bdring]

Step pulse off timing

[ggallant571]

I have been doing my own gcode processor for a couple of years using a STM32 device. Recently have started using various ESP devices for remote sensing projects. More than willing to migrate to your implementation.

[buildlog]

The solution mentioned above appears to work fine.

I removed the timer interrupt that turns off the step pulse and replaced it with a delay loop at the end of the main stepper driver interrupt (void IRAM_ATTR onStepperDriverTimer())

// wait for step pulse time to complete...some of it should have expired during code above
while (esp_timer_get_time() < step_pulse_off_time)
{
NOP(); // spin here until time to turn off step
}
set_stepper_pins_on(0); // turn all off

The stock Grbl setting is 3 uSecs, which is also the minimum. I am not sure why that is a minimum, but I'll leave it. Common drivers like the TI DRV8825 require a step pulse length of 1.9uS.

I don't think it should impact performance because the time is so brief. You can't go any faster than what the minimum step pulse timing will allow anyways. I have not profiled the code before that, but it probably uses up much of the time.

I have not committed the code yet, in case anyone wants to comment on this.

[buildlog]

For reference, here is the DRV8825 timing diagram.

[buildlog]

Changed to use method described above.