✨ Permit Linear Advance with I2S Streaming (#24684)

Marlin/Configuration_adv.h

  */
 //#define LIN_ADVANCE
 #if ENABLED(LIN_ADVANCE)
-  //#define EXTRA_LIN_ADVANCE_K // Enable for second linear advance constants
+  //#define EXTRA_LIN_ADVANCE_K // Add a second linear advance constant, configurable with M900.
   #define LIN_ADVANCE_K 0.22    // Unit: mm compression per 1mm/s extruder speed
-  //#define LA_DEBUG            // If enabled, this will generate debug information output over USB.
-  //#define EXPERIMENTAL_SCURVE // Enable this option to permit S-Curve Acceleration
+  //#define LA_DEBUG            // Print debug information to serial during operation. Disable for production use.
+  //#define EXPERIMENTAL_SCURVE // Allow S-Curve Acceleration to be used with LA.
   //#define ALLOW_LOW_EJERK     // Allow a DEFAULT_EJERK value of <10. Recommended for direct drive hotends.
+  //#define EXPERIMENTAL_I2S_LA // Allow I2S_STEPPER_STREAM to be used with LA. Performance degrades as the LA step rate reaches ~20kHz.
 #endif
 
 // @section leveling

Marlin/src/HAL/ESP32/i2s.cpp

 }
 
 void stepperTask(void *parameter) {
-  uint32_t remaining = 0;
+  uint32_t nextMainISR = 0;
+  #if ENABLED(LIN_ADVANCE)
+    uint32_t nextAdvanceISR = Stepper::LA_ADV_NEVER;
+  #endif
 
-  while (1) {
+  for (;;) {
     xQueueReceive(dma.queue, &dma.current, portMAX_DELAY);
     dma.rw_pos = 0;
 
     while (dma.rw_pos < DMA_SAMPLE_COUNT) {
       // Fill with the port data post pulse_phase until the next step
-      if (remaining) {
+      if (nextMainISR && TERN1(LIN_ADVANCE, nextAdvanceISR))
         i2s_push_sample();
-        remaining--;
-      }
-      else {
+
+      // i2s_push_sample() is also called from Stepper::pulse_phase_isr() and Stepper::advance_isr()
+      // in a rare case where both are called, we need to double decrement the counters
+      const uint8_t push_count = 1 + (!nextMainISR && TERN0(LIN_ADVANCE, !nextAdvanceISR));
+
+      #if ENABLED(LIN_ADVANCE)
+        if (!nextAdvanceISR) {
+          Stepper::advance_isr();
+          nextAdvanceISR = Stepper::la_interval;
+        }
+        else if (nextAdvanceISR == Stepper::LA_ADV_NEVER)
+          nextAdvanceISR = Stepper::la_interval;
+      #endif
+
+      if (!nextMainISR) {
         Stepper::pulse_phase_isr();
-        remaining = Stepper::block_phase_isr();
+        nextMainISR = Stepper::block_phase_isr();
       }
+
+      nextMainISR -= push_count;
+      TERN_(LIN_ADVANCE, nextAdvanceISR -= push_count);
     }
   }
 }

Marlin/src/HAL/ESP32/inc/SanityCheck.h

   #error "PULLDOWN pin mode is not available on ESP32 boards."
 #endif
 
-#if BOTH(I2S_STEPPER_STREAM, LIN_ADVANCE)
+#if BOTH(I2S_STEPPER_STREAM, LIN_ADVANCE) && DISABLED(EXPERIMENTAL_I2S_LA)
   #error "I2S stream is currently incompatible with LIN_ADVANCE."
 #endif

Marlin/src/inc/Warnings.cpp

   #warning "WARNING! Disable MARLIN_DEV_MODE for the final build!"
 #endif
 
+#if ENABLED(LA_DEBUG)
+  #warning "WARNING! Disable LA_DEBUG for the final build!"
+#endif
+
 #if NUM_AXES_WARNING
   #warning "Note: NUM_AXES is now based on the *_DRIVER_TYPE settings so you can remove NUM_AXES from Configuration.h."
 #endif

Marlin/src/module/stepper.cpp

   #include "../lcd/extui/ui_api.h"
 #endif
 
+#if ENABLED(I2S_STEPPER_STREAM)
+  #include "../HAL/ESP32/i2s.h"
+#endif
+
 // public:
 
 #if EITHER(HAS_EXTRA_ENDSTOPS, Z_STEPPER_AUTO_ALIGN)
      * On AVR the ISR epilogue+prologue is estimated at 100 instructions - Give 8µs as margin
      * On ARM the ISR epilogue+prologue is estimated at 20 instructions - Give 1µs as margin
      */
-    min_ticks = HAL_timer_get_count(MF_TIMER_STEP) + hal_timer_t(
-      #ifdef __AVR__
-        8
-      #else
-        1
-      #endif
-      * (STEPPER_TIMER_TICKS_PER_US)
-    );
+    min_ticks = HAL_timer_get_count(MF_TIMER_STEP) + hal_timer_t(TERN(__AVR__, 8, 1) * (STEPPER_TIMER_TICKS_PER_US));
 
     /**
      * NB: If for some reason the stepper monopolizes the MPU, eventually the
     // the acceleration and speed values calculated in block_phase_isr().
     // This helps keep LA in sync with, for example, S_CURVE_ACCELERATION.
     la_delta_error += la_dividend;
-    if (la_delta_error >= 0) {
+    const bool step_needed = la_delta_error >= 0;
+    if (step_needed) {
       count_position.e += count_direction.e;
       la_advance_steps += count_direction.e;
       la_delta_error -= advance_divisor;
 
       // Set the STEP pulse ON
-      #if ENABLED(MIXING_EXTRUDER)
-        E_STEP_WRITE(mixer.get_next_stepper(), !INVERT_E_STEP_PIN);
-      #else
-        E_STEP_WRITE(stepper_extruder, !INVERT_E_STEP_PIN);
-      #endif
+      E_STEP_WRITE(TERN(MIXING_EXTRUDER, mixer.get_next_stepper(), stepper_extruder), !INVERT_E_STEP_PIN);
+    }
+
+    TERN_(I2S_STEPPER_STREAM, i2s_push_sample());
 
+    if (step_needed) {
       // Enforce a minimum duration for STEP pulse ON
       #if ISR_PULSE_CONTROL
         USING_TIMED_PULSE();
       #endif
 
       // Set the STEP pulse OFF
-      #if ENABLED(MIXING_EXTRUDER)
-        E_STEP_WRITE(mixer.get_stepper(), INVERT_E_STEP_PIN);
-      #else
-        E_STEP_WRITE(stepper_extruder, INVERT_E_STEP_PIN);
-      #endif
+      E_STEP_WRITE(TERN(MIXING_EXTRUDER, mixer.get_stepper(), stepper_extruder), INVERT_E_STEP_PIN);
     }
   }
 

Marlin/src/module/stepper.h

 class Stepper {
   friend class KinematicSystem;
   friend class DeltaKinematicSystem;
+  friend void stepperTask(void *);
 
   public: