From 05ed6c122d16889a82ebaca6835a21676a6ed0e3 Mon Sep 17 00:00:00 2001 From: Sonny Jeon Date: Sun, 25 Sep 2011 19:24:29 -0600 Subject: [PATCH] Updated some comments and fixed a bug in the new stepper logic. - The stepper logic was not initiating the decelerations for certain cases. Just re-arranged the logic to fix it. --- stepper.c | 53 ++++++++++++++++++++++++++--------------------------- 1 file changed, 26 insertions(+), 27 deletions(-) diff --git a/stepper.c b/stepper.c index ea6c17f..9786387 100644 --- a/stepper.c +++ b/stepper.c @@ -71,8 +71,8 @@ static uint32_t trapezoid_adjusted_rate; // The current rate of step_events // The trapezoid is the shape the speed curve over time. It starts at block->initial_rate, accelerates by block->rate_delta // during the first block->accelerate_until step_events_completed, then keeps going at constant speed until // step_events_completed reaches block->decelerate_after after which it decelerates until the trapezoid generator is reset. -// The slope of acceleration is always +/- block->rate_delta and is applied at a constant rate by trapezoid_generator_tick() -// that is called ACCELERATION_TICKS_PER_SECOND times per second. +// The slope of acceleration is always +/- block->rate_delta and is applied at a constant rate following the midpoint rule +// by the trapezoid generator, which is called ACCELERATION_TICKS_PER_SECOND times per second. static void set_step_events_per_minute(uint32_t steps_per_minute); @@ -171,12 +171,10 @@ SIGNAL(TIMER1_COMPA_vect) // While in block steps, check for de/ac-celeration events and execute them accordingly. if (step_events_completed < current_block->step_event_count) { - - // Always check 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. - // Trapezoid de/ac-celeration is approximated by discrete increases or decreases in velocity, - // defined by ACCELERATION_TICKS_PER_SECOND and block->rate_delta. The accelerations employ the - // midpoint rule to obtain an accurate representation of the exact acceleration curve. + + // 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 @@ -193,32 +191,33 @@ SIGNAL(TIMER1_COMPA_vect) } set_step_events_per_minute(trapezoid_adjusted_rate); } - } else if (step_events_completed > current_block->decelerate_after) { - // Iterate cycle counter and check if speeds need to be reduced. - if ( iterate_trapezoid_cycle_counter() ) { - // NOTE: We will only reduce speed if the result will be > 0. This catches small - // rounding errors that might leave steps hanging after the last trapezoid tick. - if (trapezoid_adjusted_rate > current_block->rate_delta) { - trapezoid_adjusted_rate -= current_block->rate_delta; + } else if (step_events_completed >= current_block->decelerate_after) { + // 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. + if (step_events_completed == current_block-> decelerate_after) { + trapezoid_tick_cycle_counter = CYCLES_PER_ACCELERATION_TICK/2; + } else { + // Iterate cycle counter and check if speeds need to be reduced. + if ( iterate_trapezoid_cycle_counter() ) { + // NOTE: We will only reduce speed if the result will be > 0. This catches small + // rounding errors that might leave steps hanging after the last trapezoid tick. + if (trapezoid_adjusted_rate > current_block->rate_delta) { + trapezoid_adjusted_rate -= current_block->rate_delta; + } + if (trapezoid_adjusted_rate < current_block->final_rate) { + // Reached final rate a little early. Cruise to end of block at final rate. + trapezoid_adjusted_rate = current_block->final_rate; + } + set_step_events_per_minute(trapezoid_adjusted_rate); } - if (trapezoid_adjusted_rate < current_block->final_rate) { - // Reached final rate a little early. Cruise to end of block at final rate. - trapezoid_adjusted_rate = current_block->final_rate; - } - set_step_events_per_minute(trapezoid_adjusted_rate); } } else { - // No accelerations. Make sure we cruise exactly at nominal rate. + // No accelerations. Make sure we cruise exactly at the nominal rate. if (trapezoid_adjusted_rate != current_block->nominal_rate) { trapezoid_adjusted_rate = current_block->nominal_rate; set_step_events_per_minute(trapezoid_adjusted_rate); } - // Check to 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. - if (step_events_completed >= current_block-> decelerate_after) { - trapezoid_tick_cycle_counter = CYCLES_PER_ACCELERATION_TICK/2; - } } } else {