From 61a67aff316ca5b25f8169f5dce27ced23c09773 Mon Sep 17 00:00:00 2001
From: Sergey <sergey@terentiev.me>
Date: Wed, 27 May 2020 22:01:51 +0300
Subject: [PATCH] =?UTF-8?q?=D0=9E=D1=88=D0=B8=D0=B1=D0=BA=D0=B0=20=D1=81?=
 =?UTF-8?q?=D0=BB=D0=B8=D1=8F=D0=BD=D0=B8=D1=8F=20=D0=B2=D0=B5=D1=82=D0=BE?=
 =?UTF-8?q?=D0=BA?=
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---
 Marlin/src/HAL/STM32F1/eeprom.cpp | 20 ++++++--------------
 1 file changed, 6 insertions(+), 14 deletions(-)

diff --git a/Marlin/src/HAL/STM32F1/eeprom.cpp b/Marlin/src/HAL/STM32F1/eeprom.cpp
index 48daffc4f0..d10af28a8c 100644
--- a/Marlin/src/HAL/STM32F1/eeprom.cpp
+++ b/Marlin/src/HAL/STM32F1/eeprom.cpp
@@ -56,18 +56,11 @@ bool PersistentStore::write_data(int &pos, const uint8_t *value, size_t size, ui
   while (size--) {
     uint8_t * const p = (uint8_t * const)pos;
     uint8_t v = *value;
-    uint8_t r_val;
-    
-    DEBUG("Write to : %d val: %0X",pos,v);
-    r_val=eeprom_read_byte((uint16_t *)p);
-    
-    if (v != r_val) {
-      DEBUG("Read val: %0X To write val: %0X",r_val,v);
-      eeprom_write_byte((uint16_t *)p, v);
-      r_val=eeprom_read_byte((uint16_t *)p);
-      DEBUG("Read back val: %0X",r_val);
-      if (r_val != v) {
-        ERROR("Write error");
+    // EEPROM has only ~100,000 write cycles,
+    // so only write bytes that have changed!
+    if (v != eeprom_read_byte(p)) {
+      eeprom_write_byte(p, v);
+      if (eeprom_read_byte(p) != v) {
         SERIAL_ECHO_MSG(STR_ERR_EEPROM_WRITE);
         return true;
       }
@@ -81,8 +74,7 @@ bool PersistentStore::write_data(int &pos, const uint8_t *value, size_t size, ui
 
 bool PersistentStore::read_data(int &pos, uint8_t* value, size_t size, uint16_t *crc, const bool writing/*=true*/) {
   do {
-    DEBUG("Read form: %d",pos);
-    uint8_t c = eeprom_read_byte((uint16_t*)pos);
+    uint8_t c = eeprom_read_byte((uint8_t*)pos);
     if (writing && value) *value = c;
     crc16(crc, &c, 1);
     pos++;