Configure / disable PRINTCOUNTER save interval (#20856)

Co-authored-by: Scott Lahteine <github@thinkyhead.com>

Marlin/src/HAL/LPC1768/inc/Conditionals_post.h

@@ -26,3 +26,10 @@
 #elif EITHER(I2C_EEPROM, SPI_EEPROM)
   #define USE_SHARED_EEPROM 1
 #endif
+
+// LPC1768 boards seem to lose steps when saving to EEPROM during print (issue #20785)
+// TODO: Which other boards are incompatible?
+#if defined(MCU_LPC1768) && PRINTCOUNTER_SAVE_INTERVAL > 0
+  #warning "To prevent step loss, motion will pause for PRINTCOUNTER auto-save."
+  #define PRINTCOUNTER_SYNC 1
+#endif