PR26881

Fix planner wrong trap generation

If the planner `entry_rate` or `final_rate` are larger thanthe  `block->nominal_rate` then the trapezoid entry ramp continuously accelerates. Only happens if feed rate is less than MAXIMAL_STEP_RATE.

Update planner.cpp

removed

Update planner.h

Moved MINIMAL_STEP_RATE to this file.

Update planner.h

Added calc for MINIMAL_STEP_RATE

Update planner.h

fix minimal_step_rate calc

Update planner.h

Remove MINIMAL_STEP_RATE

Revert "Update planner.cpp"

This reverts commit 5e0158a8ee1340e5b0e6a7313eb5f5f7058bfa15.

Revert "Update planner.h"

This reverts commit 3da5d0c00102620dc7eddf46a30044773770a667.

Update planner.cpp

Update planner.h

Update planner.cpp

ws

Apply to min_step_rate

Marlin/src/HAL/ESP32/timers.h

@@ -53,12 +53,11 @@ typedef uint64_t hal_timer_t;
 #if ENABLED(I2S_STEPPER_STREAM)
   #define STEPPER_TIMER_PRESCALE     1
   #define STEPPER_TIMER_RATE         250000                           // 250khz, 4µs pulses of i2s word clock
-  #define STEPPER_TIMER_TICKS_PER_US ((STEPPER_TIMER_RATE) / 1000000) // stepper timer ticks per µs // wrong would be 0.25
 #else
   #define STEPPER_TIMER_PRESCALE     40
   #define STEPPER_TIMER_RATE         ((HAL_TIMER_RATE) / (STEPPER_TIMER_PRESCALE)) // frequency of stepper timer, 2MHz
-  #define STEPPER_TIMER_TICKS_PER_US ((STEPPER_TIMER_RATE) / 1000000)              // stepper timer ticks per µs
 #endif
+#define STEPPER_TIMER_TICKS_PER_US   ((STEPPER_TIMER_RATE) / 1000000) // stepper timer ticks per µs
 
 #define STEP_TIMER_MIN_INTERVAL   8 // minimum time in µs between stepper interrupts
 

Marlin/src/HAL/TEENSY31_32/timers.h

@@ -41,7 +41,7 @@ typedef uint32_t hal_timer_t;
 #define FTM0_TIMER_PRESCALE_BITS 0b011
 #define FTM1_TIMER_PRESCALE_BITS 0b010
 
-#define FTM0_TIMER_RATE (F_BUS / (FTM0_TIMER_PRESCALE)) // 60MHz / 8 = 7500kHz
+#define FTM0_TIMER_RATE (F_BUS / (FTM0_TIMER_PRESCALE)) // 60MHz / 8 = 7.5MHz
 #define FTM1_TIMER_RATE (F_BUS / (FTM1_TIMER_PRESCALE)) // 60MHz / 4 = 15MHz
 
 #define HAL_TIMER_RATE         (FTM0_TIMER_RATE)

Marlin/src/module/planner.cpp

@@ -730,8 +730,6 @@ void Planner::init() {
   #endif
 #endif
 
-#define MINIMAL_STEP_RATE 120
-
 /**
  * Get the current block for processing
  * and mark the block as busy.
@@ -784,9 +782,10 @@ block_t* Planner::get_current_block() {
 
 /**
  * Calculate trapezoid parameters, multiplying the entry- and exit-speeds
- * by the provided factors. Requires that initial_rate and final_rate are
- * no less than sqrt(block->acceleration_steps_per_s2 / 2), which is ensured
- * through minimum_planner_speed_sqr in _populate_block().
+ * by the provided factors.
+ * The factors come from the current and next entry speeds divided by the nominal speed,
+ * which is the top speed achievable during the move. Since entry and exit are presumed to
+ * be smaller, these factors should always be <= 1.0.
  **
  * ############ VERY IMPORTANT ############
  * NOTE that the PRECONDITION to call this function is that the block is
@@ -807,6 +806,15 @@ void Planner::calculate_trapezoid_for_block(block_t * const block, const_float_t
   NOLESS(final_rate, uint32_t(MINIMAL_STEP_RATE));
   NOMORE(initial_rate, block->nominal_rate);          // NOTE: The nominal rate may be less than MINIMAL_STEP_RATE!
   NOMORE(final_rate, block->nominal_rate);
+  NOLESS(block->nominal_rate, (uint32_t)MINIMAL_STEP_RATE);
+
+  // Limit minimal step rate (Otherwise the timer will overflow.)
+  NOLESS(initial_rate, MINIMAL_STEP_RATE);
+  NOLESS(final_rate, MINIMAL_STEP_RATE);
+  NOLESS(block->nominal_rate, MINIMAL_STEP_RATE);
+
+  //NOMORE(initial_rate, block->nominal_rate);
+  //NOMORE(final_rate, block->nominal_rate);
 
   #if ANY(S_CURVE_ACCELERATION, LIN_ADVANCE)
     // If we have some plateau time, the cruise rate will be the nominal rate

Marlin/src/module/planner.h

@@ -78,6 +78,14 @@
   #include "../feature/closedloop.h"
 #endif
 
+constexpr uint32_t MINIMAL_STEP_RATE = (
+  #ifdef CPU_32_BIT
+    _MAX((STEPPER_TIMER_RATE) / HAL_TIMER_TYPE_MAX, 1U) // 32-bit shouldn't go below 1
+  #else
+    (F_CPU) / 500000U   // AVR shouldn't go below 32 (16MHz) or 40 (20MHz)
+  #endif
+);
+
 // Feedrate for manual moves
 #ifdef MANUAL_FEEDRATE
   constexpr xyze_feedrate_t manual_feedrate_mm_m = MANUAL_FEEDRATE,

Marlin/src/module/stepper.cpp

@@ -2198,15 +2198,15 @@ void Stepper::pulse_phase_isr() {
 // Calculate timer interval, with all limits applied.
 hal_timer_t Stepper::calc_timer_interval(uint32_t step_rate) {
 
+  constexpr uint32_t min_step_rate = MINIMAL_STEP_RATE;
+
   #ifdef CPU_32_BIT
 
     // A fast processor can just do integer division
-    constexpr uint32_t min_step_rate = uint32_t(STEPPER_TIMER_RATE) / HAL_TIMER_TYPE_MAX;
     return step_rate > min_step_rate ? uint32_t(STEPPER_TIMER_RATE) / step_rate : HAL_TIMER_TYPE_MAX;
 
   #else
 
-    constexpr uint32_t min_step_rate = (F_CPU) / 500000U; // i.e., 32 or 40
     if (step_rate >= 0x0800) {  // higher step rate
       // AVR is able to keep up at around 65kHz Stepping ISR rate at most.
       // So values for step_rate > 65535 might as well be truncated.