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Fix LEDs glitching at startup (ESP32 only) #5337

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Fix LEDs glitching at startup (ESP32 only) #5337

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33a12f9
fix bootup output glitch by using NVM stored credentials
DedeHai Feb 1, 2026
00da21f
fix race condition
DedeHai Feb 1, 2026
c092c6f
fix typo
DedeHai Feb 1, 2026
cea77f9
add ifdef guards for ESP8266
DedeHai Feb 2, 2026
386b703
revert whitespace change
DedeHai Feb 2, 2026
2cbc7c6
clear intention on union access
DedeHai Feb 2, 2026
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28 changes: 27 additions & 1 deletion wled00/wled.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -503,7 +503,7 @@ void WLED::setup()

if (strcmp(multiWiFi[0].clientSSID, DEFAULT_CLIENT_SSID) == 0 && !configBackupExists())
showWelcomePage = true;
WiFi.persistent(false);
WiFi.persistent(false); // note: on ESP32 this is only applied if WiFi.mode() is called and only if mode changes, use low level esp_wifi_set_storage() to change storage method immediately
WiFi.onEvent(WiFiEvent);
WiFi.mode(WIFI_STA); // enable scanning
findWiFi(true); // start scanning for available WiFi-s
Expand Down Expand Up @@ -666,6 +666,27 @@ void WLED::initAP(bool resetAP)

void WLED::initConnection()
{
#ifdef ARDUINO_ARCH_ESP32
static bool firstCall = true;
bool updateWiFiNVM = false;
if (firstCall) {
// check cached WiFi config in flash, esp_wifi_get_config still contains NVM values at this point
// note: connecting to the NVM stored wifi is much faster and prevents boot-up glitches on LEDs (there is no benefit on ESP8266)
wifi_config_t cachedConfig;
esp_err_t configResult = esp_wifi_get_config( (wifi_interface_t)ESP_IF_WIFI_STA, &cachedConfig );
if( configResult == ESP_OK ) {
if (strncmp((const char*)cachedConfig.sta.ssid, multiWiFi[0].clientSSID, 32) != 0 ||
strncmp((const char*)cachedConfig.sta.password, multiWiFi[0].clientPass, 64) != 0) {
updateWiFiNVM = true; // SSID or pass changed, update NVM at next WiFi.begin() call
DEBUG_PRINTLN(F("WiFi config NVM update triggered"));
}
}
firstCall = false;
}
else
esp_wifi_set_storage(WIFI_STORAGE_RAM); // do not update NVM credentials while running to prevent wear on flash
#endif

DEBUG_PRINTF_P(PSTR("initConnection() called @ %lus.\n"), millis()/1000);
#ifdef WLED_ENABLE_WEBSOCKETS
ws.onEvent(wsEvent);
Expand Down Expand Up @@ -716,6 +737,11 @@ void WLED::initConnection()
char hostname[25];
prepareHostname(hostname);

#ifdef ARDUINO_ARCH_ESP32
if(updateWiFiNVM && selectedWiFi == 0) // NVM only can store one wifi: store credentials of first WiFi even if multiple are configured
esp_wifi_set_storage(WIFI_STORAGE_FLASH); // temporary override WiFi.persistent(false) to store credentials in flash (is reset to RAM on next initConnection() call)
#endif

#ifdef WLED_ENABLE_WPA_ENTERPRISE
if (multiWiFi[selectedWiFi].encryptionType == WIFI_ENCRYPTION_TYPE_PSK) {
DEBUG_PRINTLN(F("Using PSK"));
Expand Down