Protect pulse generation timing by disabling interrupts for longer #27131
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Description
Protect pulse generation timing by disabling interrupts within
Stepper::isr()for longer.This is a mitigation for the stepper isr jitter seen in #27115 and other sources of stepper isr jitter on other platforms. On microcontrollers with ISR prioritization, note that only higher priority ISRs can ever interrupt the stepper ISR.
Benefits
More consistent pulse timings. I've tested on LPC176x and here's some before/after logic analyzer captures:
Before:
After (edit, recaptured due to forgotten local changes):
Basically no improvements in actual printing quality/noise unless
ADAPTIVE_STEP_SMOOTHINGis enabled sinceADAPTIVE_STEP_SMOOTHINGreduces a larger source of speed jitter, namely bresenham aliasing for the minor axes.Related Issues
Mostly mitigates #27115