marlinfw/Marlin/src/feature/mmu3/mmu2.cpp

/**
 * Marlin 3D Printer Firmware
 * Copyright (c) 2024 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
 *
 * Based on Sprinter and grbl.
 * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 */

/**
 * mmu2.cpp
 */

#include "../../inc/MarlinConfigPre.h"

#if HAS_PRUSA_MMU3

#include "mmu2.h"
#include "mmu2_error_converter.h"
#include "mmu2_fsensor.h"
#include "mmu2_log.h"
#include "mmu2_marlin.h"
#include "mmu2_marlin_macros.h"
#include "mmu2_power.h"
#include "mmu2_progress_converter.h"
#include "mmu2_reporting.h"

#include "strlen_cx.h"
#include "SpoolJoin.h"

#include "../../inc/MarlinConfig.h"

#include "../../lcd/marlinui.h"
#include "../../module/planner.h"
#include "../../module/motion.h"
#include "../../gcode/parser.h"
#include "../../gcode/queue.h"
#include "../runout.h"
#if HAS_LEVELING
  #include "../bedlevel/bedlevel.h"
#endif
#include "../pause.h"
#include "../../libs/stopwatch.h"

// As of FW 3.12 we only support building the FW with only one extruder, all the multi-extruder infrastructure will be removed.
// Saves at least 800B of code size
//#ifdef __AVR__
//static_assert(EXTRUDERS == 1);
//#endif

#define MMU2_NO_TOOL 99

MMU3::MMU3 mmu3;

namespace MMU3 {

  template <typename F>
  void waitForHotendTargetTemp(uint16_t delay, F f) {
    while (((thermal_degTargetHotend() - thermal_degHotend()) > 5)) {
      f();
      safe_delay_keep_alive(delay);
    }
  }

  void WaitForHotendTargetTempBeep() {
    waitForHotendTargetTemp(3000, []{});
    //MakeSound(Prompt);
  }

  uint8_t MMU3::cutter_mode;    // Initialized by settings.load
  int MMU3::cutter_mode_addr;   // Initialized by settings.load
  uint8_t MMU3::stealth_mode;   // Initialized by settings.load
  int MMU3::stealth_mode_addr;  // Initialized by settings.load
  // TODO: Currently, by logic, the value stored in the EEPROM for is ignored and
  //       mmu_hw_enabled is always overwritten by the MMU State. Thus restarting
  //       printer will always set the MMU as senabled.
  bool MMU3::mmu_hw_enabled;    // Initialized by settings.load
  int MMU3::mmu_hw_enabled_addr; // Initialized by settings.load

  MMU3::MMU3()
    : logic(MMU2_TOOL_CHANGE_LOAD_LENGTH, MMU2_LOAD_TO_NOZZLE_FEED_RATE)
    , extruder(MMU2_NO_TOOL)
    , tool_change_extruder(MMU2_NO_TOOL)
    , resume_position()
    , resume_hotend_temp(0)
    , logicStepLastStatus(StepStatus::Finished)
    , _state(xState::Stopped)
    , mmu_print_saved(SavedState::None)
    , loadFilamentStarted(false)
    , unloadFilamentStarted(false)
    , toolchange_counter(0)
    , _tmcFailures(0) { }

  void MMU3::status() {
    // Useful information to see during bootup and change state
    SERIAL_ECHOLN(F("MMU is "), mmu_hw_enabled ? GET_TEXT_F(MSG_ON) : GET_TEXT_F(MSG_OFF));
  }

  void MMU3::start() {
    mmu_hw_enabled = true;

    #if ENABLED(EEPROM_SETTINGS)
      // Save mmu_hw_enabled to EEPROM
      // TODO: Move to settings.cpp (for now)
      persistentStore.access_start();
      persistentStore.write_data(mmu_hw_enabled_addr, mmu_hw_enabled);
      persistentStore.access_finish();
      settings.save();
    #endif

    MMU2_SERIAL.begin(MMU_BAUD);

    powerOn();
    MMU2_SERIAL.flush(); // Make sure the UART buffer is clear before starting communication

    setCurrentTool(MMU2_NO_TOOL);
    _state = xState::Connecting;

    // Start communication
    logic.start();
    logic.ResetRetryAttempts();
    logic.ResetCommunicationTimeoutAttempts();
  }

  void MMU3::stop() {
    stopKeepPowered();
    powerOff();
  }

  void MMU3::stopKeepPowered() {
    mmu_hw_enabled = false;

    #if ENABLED(EEPROM_SETTINGS)
      // Save mmu_hw_enabled to EEPROM
      persistentStore.access_start();
      persistentStore.write_data(mmu_hw_enabled_addr, mmu_hw_enabled);
      persistentStore.access_finish();
      settings.save();
    #endif

    _state = xState::Stopped;
    logic.stop();
    MMU2_SERIAL.end();
  }

  void MMU3::tune() {
    switch (lastErrorCode) {
      case ErrorCode::HOMING_SELECTOR_FAILED:
      case ErrorCode::HOMING_IDLER_FAILED: {
        // Prompt a menu for different values
        tuneIdlerStallguardThreshold();
        break;
      }
      default: break;
    }
  }

  void MMU3::reset(ResetForm level) {
    switch (level) {
      case Software:    resetX0(); break;
      case ResetPin:    triggerResetPin(); break;
      case CutThePower: powerCycle(); break;
      case EraseEEPROM: resetX42(); break;
      default: break;
    }
  }

  void MMU3::resetX0() { logic.ResetMMU(); } // Send soft reset
  void MMU3::resetX42() { logic.ResetMMU(42); }

  void MMU3::triggerResetPin() { power_reset(); }

  void MMU3::powerCycle() {
    // cut the power to the MMU and after a while restore it
    // Sadly, MK3/S/+ cannot do this
    stop();
    safe_delay_keep_alive(1000);
    start();
  }

  void MMU3::powerOff() { power_off(); }
  void MMU3::powerOn()  { power_on(); }

  bool MMU3::readRegister(uint8_t address) {
    if (!waitForMMUReady()) return false;

    do {
      logic.readRegister(address); // we may signal the accepted/rejected status of the response as return value of this function
    } while (!manage_response(false, false));

    // Update cached value
    lastReadRegisterValue = logic.rsp.paramValue;
    return true;
  }

  bool __attribute__((noinline)) MMU3::writeRegister(uint8_t address, uint16_t data) {
    if (!waitForMMUReady()) return false;

    // special cases - intercept requests of registers which influence the printer's behaviour too + perform the change even on the printer's side
    switch (address) {
      case (uint8_t)Register::Extra_Load_Distance:  logic.PlanExtraLoadDistance(data); break;
      case (uint8_t)Register::Pulley_Slow_Feedrate: logic.PlanPulleySlowFeedRate(data); break;
      default: break; // Don't intercept any other register writes
    }

    do {
      logic.writeRegister(address, data); // we may signal the accepted/rejected status of the response as return value of this function
    } while (!manage_response(false, false));

    return true;
  }

  void MMU3::mmu_loop() {
    // We only leave this method if the current command was successfully
    // completed - that's the Marlin's way of blocking operation
    // Atomic compare_exchange would have been the most appropriate solution
    // here, but this gets called only in Marlin's task, so thread safety
    // should be kept
    static bool avoidRecursion = false;
    if (avoidRecursion) return;
    avoidRecursion = true;

    mmu_loop_inner(true);

    avoidRecursion = false;
  }

  void __attribute__((noinline)) MMU3::mmu_loop_inner(bool reportErrors) {
    logicStepLastStatus = logicStep(reportErrors); // it looks like the mmu_loop doesn't need to be a blocking call
    CheckErrorScreenUserInput();
  }

  /**
   * Check if there are extruder moves planned ahead.
   *
   * TODO: This should go to the planner, but for now keep it here!
   */
  bool MMU3::e_active() {
    unsigned char e_active = 0;
    block_t *block;
    if (planner.block_buffer_tail != planner.block_buffer_head) {
      uint8_t block_index = planner.block_buffer_tail;
      while (block_index != planner.block_buffer_head) {
        block = &planner.block_buffer[block_index];
        if (block->steps[E_AXIS] != 0) e_active++;
        block_index = (block_index + 1) & (BLOCK_BUFFER_SIZE - 1);
      }
    }
    return (e_active > 0);
  }

  /**
   * Trigger an M600 or the SpoolJoin feature if the FINDA cannot detect any
   * filament during the print.
   *
   * In case of SpoolJoin feature is triggered, Marlin's implementation is a
   * little different than Prusa's, as we are completely consuming the filament
   * before switching to the next slot. There will be a little bit of filament
   * left when the new filament is extruded SpoolJoin is not intended to be used with
   * multi color/material prints so this should be fine.
   */
  void MMU3::checkFINDARunout() {
    if (!findaDetectsFilament()
        //&& printJobOngoing()
        && parser.codenum != 600
        && TERN1(HAS_LEVELING, planner.leveling_active)
        && xy_are_trusted()
        && e_active()
        #if ENABLED(MMU_SPOOL_JOIN_CONSUMES_ALL_FILAMENT)
          && runout.enabled // to prevent M600 to be triggered during M600 AUTO
          && !FILAMENT_PRESENT() // so the filament is totally consumed
        #endif
    ) {
      SERIAL_ECHOLN_P("FINDA filament runout!");
      if (spooljoin.isEnabled() && get_current_tool() != (uint8_t)FILAMENT_UNKNOWN) { // Can't auto if F=?
        #if ENABLED(MMU_SPOOL_JOIN_CONSUMES_ALL_FILAMENT)
          // set the current tool to FILAMENT_UNKNOWN so that we don't try to unload it
          extruder = MMU2_NO_TOOL;
          // disable the filament runout sensor (this is going to be re-enabled after the filament is loaded)
          runout.reset();
          runout.filament_ran_out = false; // trying to disable the purge more / continue message
          runout.enabled = false;
        #endif
        queue.enqueue_now(F("M600A")); // Save print and run M600 command
      }
      else {
        marlin_stop_and_save_print_to_ram();
        resume_print();
        queue.enqueue_now(F("M600")); // Save print and run M600 command
      }
    }
  }

  struct ReportingRAII {
    CommandInProgress cip;
    explicit inline __attribute__((always_inline)) ReportingRAII(CommandInProgress cip)
      : cip(cip) {
      BeginReport(cip, ProgressCode::EngagingIdler);
    }
    inline __attribute__((always_inline)) ~ReportingRAII() {
      EndReport(cip, ProgressCode::OK);
    }
  };

  bool MMU3::waitForMMUReady() {
    switch (state()) {
      case xState::Stopped: return false;
      case xState::Connecting:
      // Should we wait until the MMU reconnects?
      // Fire up a fsm_dlg and show "MMU not responding"?
      default: return true;
    }
  }

  bool MMU3::retryIfPossible(const ErrorCode ec) {
    if (logic.RetryAttempts()) {
      SetButtonResponse(ButtonOperations::Retry);
      // check, that Retry is actually allowed on that operation
      if (ButtonAvailable(ec) != Buttons::NoButton) {
        logic.SetInAutoRetry(true);
        SERIAL_ECHOLN_P("RetryButtonPressed");
        // We don't decrement until the button is acknowledged by the MMU.
        // --retryAttempts; // "used" one retry attempt
        return true;
      }
    }
    logic.SetInAutoRetry(false);
    return false;
  }

  bool MMU3::verifyFilamentEnteredPTFE() {
    planner_synchronize();

    if (WhereIsFilament() != FilamentState::AT_FSENSOR)
      return false;

    // MMU has finished its load, push the filament further by some defined constant length
    // If the filament sensor reads 0 at any moment, then report FAILURE
    const float tryload_length = MMU2_CHECK_FILAMENT_PRESENCE_EXTRUSION_LENGTH - logic.ExtraLoadDistance();
    TryLoadUnloadReporter tlur(tryload_length);

    /**
     * The position is a triangle wave.
     * Current position is not zero, it is an offset
     *
     * Keep in mind that the relationship between machine position
     * and pixel index is not linear. The area around the amplitude
     * needs to be taken care of carefully. The current implementation
     * handles each move separately so there is no need to watch for the change
     * in the slope's sign or check the last machine position.
     *              y(x)
     *              ▲
     *              │     ^◄────────── tryload_length + current_position
     *   machine    │    / \
     *   position   │   /   \◄────────── stepper_position_mm + current_position
     *    (mm)      │  /     \
     *              │ /       \
     *              │/         \◄───────current_position
     *              └──────────────► x
     *              0           19
     *                 pixel #
     */

    bool filament_inserted = true; // Expect success
    // Pixel index will go from 0 to 10, then back from 10 to 0.
    // A change in this value indicates a new pixel should be drawn on the display.
    for (uint8_t move = 0; move < 2; move++) {
      extruder_move(move == 0 ? tryload_length : -tryload_length, MMU2_VERIFY_LOAD_TO_NOZZLE_FEED_RATE);
      while (planner_any_moves()) {
        filament_inserted = filament_inserted && (WhereIsFilament() == FilamentState::AT_FSENSOR);
        tlur.Progress(filament_inserted);
        safe_delay_keep_alive(0);
      }
    }
    Disable_E0();
    if (!filament_inserted) IncrementLoadFails();
    tlur.DumpToSerial();
    return filament_inserted;
  }

  bool MMU3::toolChangeCommonOnce(uint8_t slot) {
    static_assert(MMU2_MAX_RETRIES > 1); // Need >1 retries to do the cut in the last attempt
    uint8_t retries = 0;
    for (;;) {
      for (;;) {
        Disable_E0(); // It may seem counterintuitive to disable the E-motor, but it gets enabled in the planner whenever the E-motor is to move
        tool_change_extruder = slot;
        logic.ToolChange(slot); // Let the MMU pull the filament out and push a new one in

        if (manage_response(true, true)) break;

        // Otherwise: failed to perform the command - unload first and then let it run again
        IncrementMMUFails();

        // Just in case we stood in an error screen for too long and the hotend got cold
        resumeHotendTemp();
        // If the extruder has been parked, it will get unparked once the ToolChange command finishes OK
        // - so no resumeUnpark() at this spot

        unloadInner();
        // If we run out of retries, we must do something ... maybe raise an error screen and allow the user to do something.
        // But honestly - if the MMU restarts during every toolchange something else is seriously broken
        // and stopping a print is probably our best option.
      }
      if (verifyFilamentEnteredPTFE()) return true; // success

      // Prepare a retry attempt
      unloadInner();
      if (retries == (MMU2_MAX_RETRIES) - 1 && cutter_enabled()) {
        cutFilamentInner(slot); // try cutting filament tip at the last attempt
        retries = 0; // reset retries every MMU2_MAX_RETRIES
      }

      ++retries;
    }
    return false; // Couldn't accomplish the task
  }

  void MMU3::toolChangeCommon(uint8_t slot) {
    while (!toolChangeCommonOnce(slot)) { // While not successfully fed into extruder's PTFE tube...
      // Failed autoretry, report an error by forcing a "printer" error into the MMU infrastructure - it is a hack to leverage existing code
      // @@TODO theoretically logic layer may not need to be spoiled with the printer error - maybe just the manage_response needs it...
      logic.SetPrinterError(ErrorCode::LOAD_TO_EXTRUDER_FAILED);
      // We only have to wait for the user to fix the issue and press "Retry".
      // Please see checkUserInput() for details how we "leave" manage_response.
      // If manage_response returns false at this spot (MMU operation interrupted aka MMU reset)
      // we can safely continue because the MMU is not doing an operation now.
      static_cast<void>(manage_response(true, true)); // yes, I'd like to silence [[nodiscard]] warning at this spot by casting to void
    }

    setCurrentTool(slot); // filament change is finished
    spooljoin.setSlot(slot);

    ++toolchange_counter;

    // Also increment the total number of tool changes
    operation_statistics.increment_tool_change_counter();
  }

  bool MMU3::tool_change(uint8_t slot) {
    if (!waitForMMUReady()) return false;

    if (slot != extruder) {
      if (
        //findaDetectsFilament()
        //!IS_SD_PRINTING() && !usb_timer.running()
        !marlin_printingIsActive()
      ) {
        // If Tcodes are used manually through the serial
        // we need to unload manually as well -- but only if FINDA detects filament
        unload();
      }

      ReportingRAII rep(CommandInProgress::ToolChange);
      FSensorBlockRunout blockRunout;
      planner_synchronize();
      toolChangeCommon(slot);
    }
    return true;
  }

  /**
   * Handle special T?/Tx/Tc commands
   *
   * - T? Gcode to extrude shouldn't have to follow, load to extruder wheels is done automatically
   * - Tx Same as T?, except nozzle doesn't have to be preheated. Tc must be placed after extruder nozzle is preheated to finish filament load.
   * - Tc Load to nozzle after filament was prepared by Tx and extruder nozzle is already heated.
   */
  bool MMU3::tool_change(char code, uint8_t slot) {
    if (!waitForMMUReady()) return false;

    FSensorBlockRunout blockRunout;

    switch (code) {
      case '?': {
        waitForHotendTargetTemp(100, []{});
        load_to_nozzle(slot);
      }
      break;

      case 'x': {
        thermal_setExtrudeMintemp(0); // Allow cold extrusion since Tx only loads to the gears not nozzle
        tool_change(slot);
        thermal_setExtrudeMintemp(EXTRUDE_MINTEMP);
      }
      break;

      case 'c': {
        waitForHotendTargetTemp(100, []{});
        execute_load_to_nozzle_sequence();
      }
      break;
    }

    return true;
  }

  void MMU3::get_statistics() {
    logic.Statistics();
  }

  uint8_t __attribute__((noinline)) MMU3::get_current_tool() const {
    return extruder == MMU2_NO_TOOL ? (uint8_t)FILAMENT_UNKNOWN : extruder;
  }

  uint8_t MMU3::get_tool_change_tool() const {
    return tool_change_extruder == MMU2_NO_TOOL ? (uint8_t)FILAMENT_UNKNOWN : tool_change_extruder;
  }

  void MMU3::setCurrentTool(uint8_t ex) {
    extruder = ex;
    MMU2_ECHO_MSGRPGM(PSTR("MMU2tool="));
    SERIAL_ECHOLN((int)ex);
  }

  bool MMU3::set_filament_type(uint8_t /*slot*/, uint8_t /*type*/) {
    if (!waitForMMUReady()) return false;

    // @@TODO - this is not supported in the new MMU yet
    //    slot = slot; // @@TODO
    //    type = type; // @@TODO
    // cmd_arg = filamentType;
    // command(MMU_CMD_F0 + index);

    if (!manage_response(false, false)) {
      // @@TODO failed to perform the command - retry
      // Comment: how is it possible for a filament type set to fail? manage_response(true, true)
    }

    return true;
  }

  void MMU3::unloadInner() {
    FSensorBlockRunout blockRunout;
    filament_ramming();

    // we assume the printer managed to relieve filament tip from the gears,
    // so repeating that part in case of an MMU restart is not necessary
    for (;;) {
      Disable_E0();
      logic.UnloadFilament();
      if (manage_response(false, true)) break;
      IncrementMMUFails();
    }
    //MakeSound(Confirm);

    // no active tool
    setCurrentTool(MMU2_NO_TOOL);
    tool_change_extruder = MMU2_NO_TOOL;
  }

  bool MMU3::unload() {
    if (!waitForMMUReady()) return false;

    WaitForHotendTargetTempBeep();

    // Scope for ReportingRAII
    {
      ReportingRAII rep(CommandInProgress::UnloadFilament);
      unloadInner();
    }

    ScreenUpdateEnable();
    return true;
  }

  void MMU3::cutFilamentInner(uint8_t slot) {
    for (;;) {
      Disable_E0();
      logic.CutFilament(slot);
      if (manage_response(false, true)) break;
      IncrementMMUFails();
    }
  }

  bool MMU3::cut_filament(uint8_t slot, bool enableFullScreenMsg /*= true*/) {
    if (!waitForMMUReady()) return false;

    if (enableFullScreenMsg) fullScreenMsgCut(slot);

    // Scope for ReportingRAII
    {
      if (findaDetectsFilament()) unload();

      ReportingRAII rep(CommandInProgress::CutFilament);
      cutFilamentInner(slot);
      setCurrentTool(MMU2_NO_TOOL);
      tool_change_extruder = MMU2_NO_TOOL;
      //MakeSound(SoundType::Confirm);
    }
    ScreenUpdateEnable();
    return true;
  }

  bool MMU3::loading_test(uint8_t slot) {
    fullScreenMsgTest(slot);
    tool_change(slot);
    planner_synchronize();
    unload();
    ScreenUpdateEnable();
    return true;
  }

  bool MMU3::load_to_feeder(uint8_t slot) {
    if (!waitForMMUReady()) return false;

    fullScreenMsgLoad(slot);

    // Scope for ReportingRAII
    {
      ReportingRAII rep(CommandInProgress::LoadFilament);
      for (;;) {
        Disable_E0();
        logic.LoadFilament(slot);
        if (manage_response(false, false)) break;
        IncrementMMUFails();
      }
      //MakeSound(SoundType::Confirm);
    }
    ScreenUpdateEnable();
    return true;
  }

  bool MMU3::load_to_nozzle(uint8_t slot) {
    if (!waitForMMUReady()) return false;

    WaitForHotendTargetTempBeep();

    fullScreenMsgLoad(slot);

    // Scope for ReportingRAII
    {
      // Used for MMU-menu operation "Load to Nozzle"
      ReportingRAII rep(CommandInProgress::ToolChange);
      FSensorBlockRunout blockRunout;

      // Filament already loaded? Free it and shape its tip properly.
      if (extruder != MMU2_NO_TOOL) filament_ramming();

      toolChangeCommon(slot);

      // Finish loading to the nozzle with finely tuned steps.
      execute_load_to_nozzle_sequence();
      //MakeSound(Confirm);
    }
    ScreenUpdateEnable();
    return true;
  }

  bool MMU3::eject_filament(uint8_t slot, bool enableFullScreenMsg /* = true */) {
    if (!waitForMMUReady()) return false;

    if (enableFullScreenMsg) fullScreenMsgEject(slot);

    // Scope for ReportingRAII
    {
      if (findaDetectsFilament())
        unload();

      ReportingRAII rep(CommandInProgress::EjectFilament);
      for (;;) {
        Disable_E0();
        logic.EjectFilament(slot);
        if (manage_response(false, true))
          break;
        IncrementMMUFails();
      }
      setCurrentTool(MMU2_NO_TOOL);
      tool_change_extruder = MMU2_NO_TOOL;
      //MakeSound(Confirm);
    }
    ScreenUpdateEnable();
    return true;
  }

  void MMU3::button(uint8_t index) {
    LogEchoEvent(F("button"));
    logic.button(index);
  }

  void MMU3::home(uint8_t mode) {
    logic.home(mode);
  }

  void MMU3::saveHotendTemp(bool turn_off_nozzle) {
    if (mmu_print_saved & SavedState::Cooldown) return;

    if (turn_off_nozzle && !(mmu_print_saved & SavedState::CooldownPending)) {
      Disable_E0();
      resume_hotend_temp = thermal_degTargetHotend();
      mmu_print_saved |= SavedState::CooldownPending;
      LogEchoEvent(F("Heater cooldown pending"));
    }
  }

  void MMU3::saveAndPark(bool move_axes) {
    if (mmu_print_saved == SavedState::None) { // First occurrence. Save current position, park print head, disable nozzle heater.
      LogEchoEvent(F("Saving and parking"));
      Disable_E0();
      planner_synchronize();

      // In case a power panic happens while waiting for the user
      // take a partial back up of print state into RAM (current position, etc.)
      marlin_refresh_print_state_in_ram();

      if (move_axes) {
        mmu_print_saved |= SavedState::ParkExtruder;
        resume_position = planner_current_position(); // save current pos

        // Do not lift Z, as it will double lift if there is another error
        // right after the current one is solved.

        // Move XY aside
        if (xy_are_trusted()) nozzle_park();
      }
    }
  }

  void MMU3::resumeHotendTemp() {
    if ((mmu_print_saved & SavedState::CooldownPending)) {
      // Clear the "pending" flag if we haven't cooled yet.
      mmu_print_saved &= ~(SavedState::CooldownPending);
      LogEchoEvent(F("Cooldown flag cleared"));
    }
    if ((mmu_print_saved & SavedState::Cooldown) && resume_hotend_temp) {
      LogEchoEvent(F("Resuming Temp"));
      // @@TODO MMU2_ECHO_MSGRPGM(PSTR("Restoring hotend temperature "));
      SERIAL_ECHOLN(resume_hotend_temp);
      mmu_print_saved &= ~(SavedState::Cooldown);
      thermal_setTargetHotend(resume_hotend_temp);
      fullScreenMsgRestoringTemperature();
      // @todo better report the event and let the GUI do its work somewhere else
      ReportErrorHookSensorLineRender();
      waitForHotendTargetTemp(100, [] {
        marlin_manage_inactivity(true);
        mmu3.mmu_loop_inner(false);
        ReportErrorHookDynamicRender();
      });
      ScreenUpdateEnable(); // temporary hack to stop this locking the printer...
      LogEchoEvent(F("Hotend temperature reached"));
      ScreenClear();
    }
  }

  void MMU3::resumeUnpark() {
    if (mmu_print_saved & SavedState::ParkExtruder) {
      LogEchoEvent(F("Resuming XYZ"));

      // Move XY to starting position, then Z
      motion_do_blocking_move_to_xy(resume_position.x, resume_position.x, feedRate_t(NOZZLE_PARK_XY_FEEDRATE));

      // Move Z_AXIS to saved position
      motion_do_blocking_move_to_z(resume_position.z, feedRate_t(NOZZLE_PARK_Z_FEEDRATE));

      // From this point forward, power panic should not use
      // the partial backup in RAM since the extruder is no
      // longer in parking position
      marlin_clear_print_state_in_ram();

      mmu_print_saved &= ~(SavedState::ParkExtruder);
    }
  }

  void MMU3::checkUserInput() {
    auto btn = ButtonPressed(lastErrorCode);

    // Was a button pressed on the MMU itself instead of the LCD?
    if (btn == Buttons::NoButton && lastButton != Buttons::NoButton) {
      btn = lastButton;
      lastButton = Buttons::NoButton; // Clear it.
    }

    if (mmuLastErrorSource() == MMU3::ErrorSourcePrinter && btn != Buttons::NoButton) {
      // When the printer has raised an error screen, and a button was selected
      // the error screen should always be dismissed.
      clearPrinterError();
      // A horrible hack - clear the explicit printer error allowing manage_response to recover on MMU's Finished state
      // Moreover - if the MMU is currently doing something (like the LoadFilament - see comment above)
      // we'll actually wait for it automagically in manage_response and after it finishes correctly,
      // we'll issue another command (like toolchange)
    }

    switch (btn) {
      case Buttons::Left:
      case Buttons::Middle:
      case Buttons::Right:
        SERIAL_ECHOPGM("checkUserInput-btnLMR ");
        SERIAL_ECHOLN((int)buttons_to_uint8t(btn));
        resumeHotendTemp(); // Recover the hotend temp before we attempt to do anything else...

        if (mmuLastErrorSource() == MMU3::ErrorSourceMMU)
          // Do not send a button to the MMU unless the MMU is in error state
          button(buttons_to_uint8t(btn));

        // A quick hack: for specific error codes move the E-motor every time.
        // Not sure if we can rely on the fsensor.
        // Just plan the move, let the MMU take over when it is ready
        switch (lastErrorCode) {
          case ErrorCode::FSENSOR_DIDNT_SWITCH_OFF:
          case ErrorCode::FSENSOR_TOO_EARLY: helpUnloadToFinda(); break;
          default: break;
        }
        break;
      case Buttons::TuneMMU:
        tune();
        break;
      case Buttons::Load:
      case Buttons::Eject:
        // High level operation
        setPrinterButtonOperation(btn);
        break;
      case Buttons::ResetMMU:
        reset(ResetPin); // Cannot do power cycle on the MK3
        // ... but mmu2_power.cpp knows this and triggers a soft-reset instead.
        break;
      case Buttons::DisableMMU:
        stop();
        //DisableMMUInSettings(); // stop() already does this...
        status();
        break;
      case Buttons::StopPrint:
        // @@TODO Unsure if we should handle this high level operation at this spot
        break;
      default: break;
    }
  }

  /**
   * Originally, this was used to wait for response and deal with timeout if necessary.
   * The new protocol implementation enables much nicer and intense reporting, so this method will boil down
   * just to verify the result of an issued command (which was basically the original idea)
   *
   * It is closely related to mmu_loop() (which corresponds to our ProtocolLogic::Step()), which does NOT perform any blocking wait for a command to finish.
   * But - in case of an error, the command is not yet finished, but we must react accordingly - move the printhead elsewhere, stop heating, eat a cat or so.
   * That's what's being done here...
   */
  bool MMU3::manage_response(const bool move_axes, const bool turn_off_nozzle) {
    mmu_print_saved = SavedState::None;

    MARLIN_KEEPALIVE_STATE_IN_PROCESS;

    Stopwatch nozzle_timer;

    for (;;) {
      // in our new implementation, we know the exact state of the MMU at any moment, we do not have to wait for a timeout
      // So in this case we should decide if the operation is:
      // - still running -> wait normally in idle()
      // - failed -> then do the safety moves on the printer like before
      // - finished ok -> proceed with reading other commands
      safe_delay_keep_alive(0); // calls logicStep() and remembers its return status

      if (mmu_print_saved & SavedState::CooldownPending) {
        if (!nozzle_timer.isRunning()) {
          nozzle_timer.start();
          LogEchoEvent(F("Cooling Timeout started"));
        }
        else if (nozzle_timer.duration() > (PAUSE_PARK_NOZZLE_TIMEOUT * 1000ul)) { // mins->msec.
          mmu_print_saved &= ~(SavedState::CooldownPending);
          mmu_print_saved |= SavedState::Cooldown;
          thermal_setTargetHotend(0);
          LogEchoEvent(F("Heater cooldown"));
        }
      }
      else if (nozzle_timer.isRunning()) {
        nozzle_timer.stop();
        LogEchoEvent(F("Cooling timer stopped"));
      }

      switch (logicStepLastStatus) {
        case Finished:
          // command/operation completed, let Marlin continue its work
          // the E may have some more moves to finish - wait for them
          resumeHotendTemp();
          resumeUnpark();         // We can now travel back to the tower or wherever we were when we saved.
          if (!TuneMenuEntered()) {
            // If the error screen is sleeping (running 'Tune' menu)
            // then don't reset retry attempts because we this will trigger
            // an automatic retry attempt when 'Tune' button is selected. We want the
            // error screen to appear once more so the user can hit 'Retry' button manually.
            logic.ResetRetryAttempts(); // Reset the retry counter.
          }
          planner_synchronize();
          return true;
        case Interrupted:
          // now what :D ... big bad ... ramming, unload, retry the whole command originally issued
          return false;
        case VersionMismatch: // this basically means the MMU will be disabled until reconnected
          checkUserInput();
          return true;
        case PrinterError:
          saveAndPark(move_axes);
          saveHotendTemp(turn_off_nozzle);
          checkUserInput();
          // if button pressed "Done", return true, otherwise stay within manage_response
          // Please see checkUserInput() for details how we "leave" manage_response
          break;
        case CommandError:
        case CommunicationTimeout:
        case ProtocolError:
        case ButtonPushed:
          if (!logic.InAutoRetry()) {
            // Don't proceed to the park/save if we are doing an autoretry.
            saveAndPark(move_axes);
            saveHotendTemp(turn_off_nozzle);
            checkUserInput();
          }
          break;
        case CommunicationRecovered: // @@TODO communication recovered and maybe an error recovered as well
          // Maybe the logic layer can detect the change of state a respond with one "Recovered" to be handled here
          resumeHotendTemp();
          resumeUnpark();
          break;
        case Processing: // Wait for the MMU to respond
        default: break;
      }
    }
  }

  StepStatus MMU3::logicStep(bool reportErrors) {
    // Process any buttons before proceeding with another MMU Query
    checkUserInput();

    const StepStatus ss = logic.Step();
    switch (ss) {

      case Finished:
        // At this point it is safe to trigger a runout and not interrupt the MMU protocol
        checkFINDARunout();
        break;

      case Processing:
        onMMUProgressMsg(logic.Progress());
        break;

      case ButtonPushed:
        lastButton = logic.button();
        LogEchoEvent(F("MMU button pushed"));
        checkUserInput(); // Process the button immediately
        break;

      case Interrupted:
        // can be silently handed over to a higher layer, no processing necessary at this spot
        break;

      default:
        if (reportErrors) {
          switch (ss) {

            case CommandError:
              reportError(logic.Error(), ErrorSourceMMU);
              break;

            case CommunicationTimeout:
              _state = xState::Connecting;
              reportError(ErrorCode::MMU_NOT_RESPONDING, ErrorSourcePrinter);
              break;

            case ProtocolError:
              _state = xState::Connecting;
              reportError(ErrorCode::PROTOCOL_ERROR, ErrorSourcePrinter);
              break;

            case VersionMismatch:
              stopKeepPowered();
              reportError(ErrorCode::VERSION_MISMATCH, ErrorSourcePrinter);
              break;

            case PrinterError:
              reportError(logic.PrinterError(), ErrorSourcePrinter);
              break;

            default:
              break;
          }
        }
    }

    if (logic.Running()) _state = xState::Active;

    return ss;
  }

  void MMU3::filament_ramming() {
    execute_extruder_sequence(ramming_sequence, sizeof(ramming_sequence) / sizeof(E_Step));
  }

  void MMU3::execute_extruder_sequence(const E_Step *sequence, uint8_t steps) {
    planner_synchronize();

    const E_Step *step = sequence;
    for (uint8_t i = steps; i > 0; --i) {
      extruder_move(pgm_read_float(&(step->extrude)), pgm_read_float(&(step->feedRate)));
      step++;
    }
    planner_synchronize(); // it looks like it's better to sync the moves at the end - smoother move (if the sequence is not too long).

    Disable_E0();
  }

  void MMU3::execute_load_to_nozzle_sequence() {
    planner_synchronize();
    // Compensate for configurable Extra Loading Distance
    planner_set_current_position_E(planner_get_current_position_E() - (logic.ExtraLoadDistance() - MMU2_FILAMENT_SENSOR_POSITION));
    execute_extruder_sequence(load_to_nozzle_sequence, sizeof(load_to_nozzle_sequence) / sizeof(load_to_nozzle_sequence[0]));
  }

  void MMU3::reportError(ErrorCode ec, ErrorSource res) {
    // Due to a potential lossy error reporting layers linked to this hook
    // we'd better report everything to make sure especially the error states
    // do not get lost.
    // - The good news here is the fact, that the MMU reports the errors repeatedly until resolved.
    // - The bad news is, that MMU not responding may repeatedly occur on printers not having the MMU at all.
    //
    // Not sure how to properly handle this situation, options:
    // - skip reporting "MMU not responding" (at least for now)
    // - report only changes of states (we can miss an error message)
    // - maybe some combination of MMUAvailable + UseMMU flags and decide based on their state
    // Right now the filtering of MMU_NOT_RESPONDING is done in ReportErrorHook() as it is not a problem if mmu2.cpp

    // Depending on the Progress code, we may want to do some action when an error occurs
    switch (logic.Progress()) {
      case ProgressCode::UnloadingToFinda:
        unloadFilamentStarted = false;
        planner_abort_queued_moves(); // Abort excess E-moves to be safe
        break;
      case ProgressCode::FeedingToFSensor:
        // FSENSOR error during load. Make sure E-motor stops moving.
        loadFilamentStarted = false;
        planner_abort_queued_moves(); // Abort excess E-moves to be safe
        break;
      default: break;
    }

    if (ec != lastErrorCode) { // deduplicate: only report changes in error codes into the log
      lastErrorCode = ec;
      lastErrorSource = res;
      LogErrorEvent(PrusaErrorTitle(PrusaErrorCodeIndex(ec)));

      if (ec != ErrorCode::OK && ec != ErrorCode::FILAMENT_EJECTED && ec != ErrorCode::FILAMENT_CHANGE) {
        IncrementMMUFails();

        // Check if it is a "power" failure. TMC-related errors are considered power failures.
        static constexpr uint16_t tmcMask =
          (  (uint16_t)ErrorCode::TMC_IOIN_MISMATCH
           | (uint16_t)ErrorCode::TMC_RESET
           | (uint16_t)ErrorCode::TMC_UNDERVOLTAGE_ON_CHARGE_PUMP
           | (uint16_t)ErrorCode::TMC_SHORT_TO_GROUND
           | (uint16_t)ErrorCode::TMC_OVER_TEMPERATURE_WARN
           | (uint16_t)ErrorCode::TMC_OVER_TEMPERATURE_ERROR
           | (uint16_t)ErrorCode::MMU_SOLDERING_NEEDS_ATTENTION ) & 0x7FFFU; // skip the top bit

        static_assert(tmcMask == 0x7E00); // Just make sure we fail compilation if any of the TMC error codes change

        if ((uint16_t)ec & tmcMask) { // @@TODO can be optimized to uint8_t operation
          // TMC-related errors are from 0x8200 higher
          incrementTMCFailures();
        }
      }
    }

    if (!retryIfPossible(ec))
      // If retry attempts are all used up
      // or if 'Retry' operation is not available
      // raise the MMU error screen and wait for user input
      ReportErrorHook((CommandInProgress)logic.CommandInProgress(), ec, uint8_t(lastErrorSource));
  }

  void MMU3::reportProgress(ProgressCode pc) {
    ReportProgressHook((CommandInProgress)logic.CommandInProgress(), pc);
    LogEchoEvent(ProgressCodeToText(pc));
  }

  void MMU3::onMMUProgressMsg(ProgressCode pc) {
    if (pc != lastProgressCode)
      onMMUProgressMsgChanged(pc);
    else
      onMMUProgressMsgSame(pc);
  }

  void MMU3::onMMUProgressMsgChanged(ProgressCode pc) {
    reportProgress(pc);
    lastProgressCode = pc;
    switch (pc) {
      case ProgressCode::UnloadingToFinda:
        if (  (CommandInProgress)logic.CommandInProgress() == CommandInProgress::UnloadFilament
          || ((CommandInProgress)logic.CommandInProgress() == CommandInProgress::ToolChange)
        ) {
          // If MK3S sent U0 command, ramming sequence takes care of releasing the filament.
          // If Toolchange is done while printing, PrusaSlicer takes care of releasing the filament
          // If printing is not in progress, ToolChange will issue a U0 command.
          break;
        }
        else {
          // We're likely recovering from an MMU error
          planner_synchronize();
          unloadFilamentStarted = true;
          helpUnloadToFinda();
        }
        break;
      case ProgressCode::FeedingToFSensor:
        // prepare for the movement of the E-motor
        planner_synchronize();
        loadFilamentStarted = true;
        break;
      default: break; // do nothing yet
    }
  }

  void __attribute__((noinline)) MMU3::helpUnloadToFinda() {
    extruder_move(-MMU2_RETRY_UNLOAD_TO_FINDA_LENGTH, MMU2_RETRY_UNLOAD_TO_FINDA_FEED_RATE);
  }

  void MMU3::onMMUProgressMsgSame(ProgressCode pc) {
    const uint8_t pulley_slow_feedrate = logic.PulleySlowFeedRate();
    const float extrude_distance = _MIN(_MAX(EXTRUDE_MAXLENGTH - 1, 1), pulley_slow_feedrate);

    switch (pc) {
      case ProgressCode::UnloadingToFinda:
        if (unloadFilamentStarted && !planner_any_moves()) { // Only plan a move if there is no move ongoing
          switch (WhereIsFilament()) {
            case FilamentState::AT_FSENSOR:
            case FilamentState::IN_NOZZLE:
            case FilamentState::UNAVAILABLE: // actually Unavailable makes sense as well to start the E-move to release the filament from the gears
              helpUnloadToFinda();
              break;
            default:
              unloadFilamentStarted = false;
          }
        }
        break;

      case ProgressCode::FeedingToFSensor:
        if (loadFilamentStarted) {
          switch (WhereIsFilament()) {
            case FilamentState::AT_FSENSOR:
              // fsensor triggered, finish FeedingToExtruder state
              loadFilamentStarted = false;

              // Abort any excess E-move from the planner queue
              planner_abort_queued_moves();

              // After the MMU knows the FSENSOR is triggered it will:
              // 1. Push the filament by additional 30mm (see fsensorToNozzle)
              // 2. Disengage the idler and push another 2mm.
              extruder_move(logic.ExtraLoadDistance() + 2, logic.PulleySlowFeedRate());
              break;
            case FilamentState::NOT_PRESENT:
              // fsensor not triggered, continue moving extruder
              //
              // Instead of doing a very long extrude as in PrusaFirmware,
              // Marlin's own MMU2s code has a better approach to this by spinning
              // the extruder indefinitelly...
              //
              // this ensures that while the MMU is pushing the filament,
              // the extruder will keep rotating, preventing the filament to hit
              // the extruder gears...
              while (planner.movesplanned() < 3) {
                extruder_move(extrude_distance, pulley_slow_feedrate, false);
              }
              break;
            default: break; // Abort here?
          }
        }
        break;

      default: break; // do nothing yet
    }
  }

} // MMU3

#endif // HAS_PRUSA_MMU3