PFW-1397 To reserve EEPROM write cycles, only update toolchange counter when a print finishes or is stopped

Firmware/Marlin_main.cpp

@@ -9850,6 +9850,10 @@ void save_statistics(unsigned long _total_filament_used, unsigned long _total_pr
 
 	total_filament_used = 0;
 
+  if (MMU2::mmu2.Enabled())
+  {
+    MMU2::mmu2.update_tool_change_counter_eeprom();
+  }
 }
 
 float calculate_extruder_multiplier(float diameter) {

Firmware/mmu2.cpp

@@ -118,6 +118,7 @@ MMU2::MMU2()
     , loadingToNozzle(false)
     , inAutoRetry(false)
     , retryAttempts(MAX_RETRIES)
+    , toolchange_counter(0)
 {
 }
 
@@ -301,10 +302,11 @@ void MMU2::DecrementRetryAttempts(){
     }
 }
 
-void MMU2::increment_tool_change_counter()
+void MMU2::update_tool_change_counter_eeprom()
 {
     uint32_t toolchanges = eeprom_read_dword((uint32_t*)EEPROM_TOTAL_TOOLCHANGE_COUNT);
-    eeprom_write_dword((uint32_t *)EEPROM_TOTAL_TOOLCHANGE_COUNT, ++toolchanges);
+    eeprom_update_dword((uint32_t *)EEPROM_TOTAL_TOOLCHANGE_COUNT, toolchanges + (uint32_t)read_toolchange_counter());
+    reset_toolchange_counter();
 }
 
 bool MMU2::tool_change(uint8_t index) {

Firmware/mmu2.h

@@ -182,7 +182,7 @@ public:
     bool is_mmu_error_monitor_active;
 
     /// Method to read-only mmu_print_saved
-    bool MMU_PRINT_SAVED() const { return mmu_print_saved != SavedState::None; }
+    inline bool MMU_PRINT_SAVED() const { return mmu_print_saved != SavedState::None; }
 
     /// Automagically "press" a Retry button if we have any retry attempts left
     /// @param ec ErrorCode enum value
@@ -193,9 +193,19 @@ public:
     // Called by the MMU protocol when a sent button is acknowledged.
     void DecrementRetryAttempts();
 
-private:
     /// increments tool change counter in EEPROM
-    void increment_tool_change_counter();
+    /// ATmega2560 EEPROM has only 100'000 write/erase cycles
+    /// so we can't call this function on every tool change.
+    void update_tool_change_counter_eeprom();
+
+    /// @return count for toolchange in current print
+    inline uint16_t read_toolchange_counter() const { return toolchange_counter; };
+
+    inline void reset_toolchange_counter() { toolchange_counter = 0; };
+
+private:
+    // Increment the toolchange counter via SRAM to reserve EEPROM write cycles
+    inline void increment_tool_change_counter() { ++toolchange_counter; };
 
     /// Reset the retryAttempts back to the default value
     void ResetRetryAttempts();
@@ -291,6 +301,7 @@ private:
     
     bool inAutoRetry;
     uint8_t retryAttempts;
+    uint16_t toolchange_counter;
 };
 
 /// following Marlin's way of doing stuff - one and only instance of MMU implementation in the code base