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Reduce Step Smoothing ceiling to 50% CPU usage (#18719)

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Jason Smith 2020-07-19 19:53:29 -07:00 committed by GitHub
parent 4a55bdb165
commit a847f37d43
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 7 additions and 5 deletions
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4
Marlin/src/module/stepper.cpp
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@ -2099,10 +2099,10 @@ uint32_t Stepper::block_phase_isr() {
#if ENABLED(ADAPTIVE_STEP_SMOOTHING)
uint8_t oversampling = 0; // Assume no axis smoothing (via oversampling)
// Decide if axis smoothing is possible
uint32_t max_rate = current_block->nominal_rate; // Get the maximum rate (maximum event speed)
uint32_t max_rate = current_block->nominal_rate; // Get the step event rate
while (max_rate < MIN_STEP_ISR_FREQUENCY) { // As long as more ISRs are possible...
max_rate <<= 1; // Try to double the rate
if (max_rate >= MAX_STEP_ISR_FREQUENCY_1X) break; // Don't exceed the estimated ISR limit
if (max_rate < MIN_STEP_ISR_FREQUENCY) // Don't exceed the estimated ISR limit
++oversampling; // Increase the oversampling (used for left-shift)
}
oversampling_factor = oversampling; // For all timer interval calculations

6
Marlin/src/module/stepper.h
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@ -229,8 +229,10 @@
#define MAX_STEP_ISR_FREQUENCY_2X ((F_CPU) / ISR_EXECUTION_CYCLES(2))
#define MAX_STEP_ISR_FREQUENCY_1X ((F_CPU) / ISR_EXECUTION_CYCLES(1))
// The minimum allowable frequency for step smoothing will be 1/10 of the maximum nominal frequency (in Hz)
#define MIN_STEP_ISR_FREQUENCY MAX_STEP_ISR_FREQUENCY_1X
// The minimum step ISR rate used by ADAPTIVE_STEP_SMOOTHING to target 50% CPU usage
// This does not account for the possibility of multi-stepping.
// Perhaps DISABLE_MULTI_STEPPING should be required with ADAPTIVE_STEP_SMOOTHING.
#define MIN_STEP_ISR_FREQUENCY (MAX_STEP_ISR_FREQUENCY_1X / 2)
//
// Stepper class definition