Z Offset now stored into EEPROM immediately.

Marlin/Conditionals_LulzBot.h

@@ -37,7 +37,7 @@
     #error Must specify model and toolhead. Please see "Configuration_LulzBot.h" for directions.
 #endif
 
-#define LULZBOT_FW_VERSION ".19"
+#define LULZBOT_FW_VERSION ".20"
 
 // Select options based on printer model
 
@@ -749,4 +749,44 @@
     #define LULZBOT_AFTER_Z_HOME_ACTION
 #endif
 
+/* Historically, the Lulzbot firmware would save the Z-Offset into the EEPROM
+ * each time it is changed. The latest Marlin made this more difficult since they
+ * added a CRC to the EEPROM. We work around this by bracketing the EEPROM_READ
+ * and EEPROM_WRITE routines such that the CRC ignores the Z-Offset value. That
+ * code also captures the eeprom_index so we can write only that value later.
+ */
+
+/* The following goes in "configuration_store.cpp", before and after
+ * "EEPROM_WRITE(zprobe_zoffset)" and "EEPROM_READ(zprobe_zoffset)"
+ */
+#define LULZBOT_EEPROM_BEFORE_ZOFFSET \
+    const uint16_t eeprom_saved_crc = working_crc; \
+    eeprom_zoffset_index = eeprom_index;
+
+#define LULZBOT_EEPROM_AFTER_ZOFFSET \
+    working_crc = eeprom_saved_crc;
+
+/* The following goes in "configuration_store.h" */
+#define LULZBOT_SAVE_ZOFFSET_TO_EEPROM_DECL \
+    static int eeprom_zoffset_index; \
+    static void store_zoffset();
+
+/* The following goes in "configuration_store.cpp" */
+#define LULZBOT_SAVE_ZOFFSET_TO_EEPROM_IMPL \
+    int MarlinSettings::eeprom_zoffset_index = -1; \
+    void MarlinSettings::store_zoffset() { \
+        if(eeprom_zoffset_index > 0) { \
+            uint16_t working_crc; \
+            int eeprom_index = eeprom_zoffset_index; \
+            EEPROM_WRITE(zprobe_zoffset); \
+            SERIAL_ECHO_START(); \
+            SERIAL_ECHOPAIR("Updating zoffset in EEPROM: ", zprobe_zoffset); \
+            SERIAL_ECHOPAIR("; EEPROM Index: ", eeprom_zoffset_index); \
+            SERIAL_ECHOLNPGM(""); \
+        } \
+    }
+
+/* The following goes in "ultralcd.cpp" in "lcd_babystep_zoffset" */
+#define LULZBOT_SAVE_ZOFFSET_TO_EEPROM settings.store_zoffset();
+
 #endif /* CONDITIONALS_LULZBOT */

Marlin/configuration_store.cpp

@@ -300,6 +300,8 @@ void MarlinSettings::postprocess() {
     } while (--size);
   }
 
+  LULZBOT_SAVE_ZOFFSET_TO_EEPROM_IMPL
+
   /**
    * M500 - Store Configuration
    */
@@ -393,7 +395,9 @@ void MarlinSettings::postprocess() {
     #if !HAS_BED_PROBE
       const float zprobe_zoffset = 0;
     #endif
+    LULZBOT_EEPROM_BEFORE_ZOFFSET
     EEPROM_WRITE(zprobe_zoffset);
+    LULZBOT_EEPROM_AFTER_ZOFFSET
 
     //
     // Planar Bed Leveling matrix
@@ -789,7 +793,9 @@ void MarlinSettings::postprocess() {
       #if !HAS_BED_PROBE
         float zprobe_zoffset;
       #endif
+      LULZBOT_EEPROM_BEFORE_ZOFFSET
       EEPROM_READ(zprobe_zoffset);
+      LULZBOT_EEPROM_AFTER_ZOFFSET
 
       //
       // Planar Bed Leveling matrix

Marlin/configuration_store.h

@@ -58,6 +58,8 @@ class MarlinSettings {
       static void report(bool forReplay=false) { UNUSED(forReplay); }
     #endif
 
+    LULZBOT_SAVE_ZOFFSET_TO_EEPROM_DECL
+
   private:
     static void postprocess();
 

Marlin/ultralcd.cpp

@@ -1008,7 +1008,7 @@ void kill_screen(const char* lcd_msg) {
     #if ENABLED(BABYSTEP_ZPROBE_OFFSET)
 
       void lcd_babystep_zoffset() {
-        if (lcd_clicked) { defer_return_to_status = false; return lcd_goto_previous_menu(); }
+        if (lcd_clicked) { defer_return_to_status = false; LULZBOT_SAVE_ZOFFSET_TO_EEPROM; return lcd_goto_previous_menu(); }
         defer_return_to_status = true;
         ENCODER_DIRECTION_NORMAL();
         if (encoderPosition) {