From 586d3c27325cc8f232e1f0cfc8249f8650c514ee Mon Sep 17 00:00:00 2001
From: Frank <91616163+softhack007@users.noreply.github.com>
Date: Mon, 5 Jan 2026 11:22:53 +0100
Subject: [PATCH] another attempt to prevent glitches caused by file access

wait for LEDs send out to finish, then access presets.json
---
 wled00/file.cpp    |  6 ++++++
 wled00/presets.cpp | 12 ++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/wled00/file.cpp b/wled00/file.cpp
index bf8ef929..6ac56161 100644
--- a/wled00/file.cpp
+++ b/wled00/file.cpp
@@ -547,6 +547,12 @@ bool handleFileRead(AsyncWebServerRequest* request, String path){
   }
   #endif
 
+  // wait for strip to finish updating, accessing FS during sendout causes glitches
+  #ifdef ARDUINO_ARCH_ESP32
+  unsigned wait_start = millis();
+  while (strip.isUpdating() && (millis() - wait_start < 40)) delay(1); // wait max 40ms
+  #endif
+
   if(WLED_FS.exists(path) || WLED_FS.exists(path + ".gz")) {
       request->send(WLED_FS, path, String(), request->hasArg(F("download")));
     return true;
diff --git a/wled00/presets.cpp b/wled00/presets.cpp
index c4fe6574..e675b63b 100644
--- a/wled00/presets.cpp
+++ b/wled00/presets.cpp
@@ -49,6 +49,12 @@ static void doSaveState() {
     return;
   }
 
+  // wait for strip to finish updating, accessing FS during sendout causes glitches
+  #ifdef ARDUINO_ARCH_ESP32
+  unsigned wait_start = millis();
+  while (strip.isUpdating() && (millis() - wait_start < 40)) delay(1); // wait max 40ms
+  #endif
+
   initPresetsFile(); // just in case if someone deleted presets.json using /edit
   JsonObject sObj = doc.to<JsonObject>();
 
@@ -357,6 +363,12 @@ void savePreset(byte index, const char* pname, JsonObject sObj)
       sObj.remove(F("psave"));
       if (sObj["n"].isNull()) sObj["n"] = saveName;
 
+      // wait for strip to finish updating, accessing FS during sendout causes glitches
+      #ifdef ARDUINO_ARCH_ESP32
+      unsigned wait_start = millis();
+      while (strip.isUpdating() && (millis() - wait_start < 40)) delay(1); // wait max 40ms
+      #endif
+
       initPresetsFile(); // just in case if someone deleted presets.json using /edit
       writeObjectToFileUsingId(getFileName(index<255), index, fileDoc);