From 1ff7d3181e6e85466d4faa70444a1be03dea20fa Mon Sep 17 00:00:00 2001
From: Robert Vollmer <dev@robv.de>
Date: Fri, 11 Oct 2024 23:33:19 +0200
Subject: [PATCH] Don't write config to flash if it hasn't changed

---
 Firmware/LowLevel/src/main.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Firmware/LowLevel/src/main.cpp b/Firmware/LowLevel/src/main.cpp
index 4b5edc38..6d113ea9 100644
--- a/Firmware/LowLevel/src/main.cpp
+++ b/Firmware/LowLevel/src/main.cpp
@@ -120,6 +120,7 @@ uint16_t ui_interval = 1000;               // UI send msg (LED/State) interval (
 
 struct ll_high_level_config llhl_config;  // LL/HL configuration (is initialized with YF-C500 defaults)
 const String CONFIG_FILENAME = "/openmower.cfg";
+uint16_t config_crc_in_flash = 0;
 
 void sendMessage(void *message, size_t size);
 void sendUIMessage(void *message, size_t size);
@@ -812,7 +813,7 @@ void sendUIMessage(void *message, size_t size) {
 
 void saveConfigToFlash() {
     uint16_t crc = CRC16.ccitt((const uint8_t*) &llhl_config, sizeof(llhl_config));
-    // TODO: Return early if CRC is unchanged to avoid flash wear.
+    if (crc == config_crc_in_flash) return;
 
     File f = LittleFS.open(CONFIG_FILENAME, "w");
     f.write((const uint8_t*) &llhl_config, sizeof(llhl_config));
@@ -843,6 +844,7 @@ void readConfigFromFlash() {
         buffer[size - 2] != (crc & 0xFF))
         return;
 
+    config_crc_in_flash = crc;
     applyConfig(buffer, size);
     free(buffer);
 }