From 7bfb747a4bf48bfe2d38240b5cf4229967be8e39 Mon Sep 17 00:00:00 2001
From: limpkin <limpkin@limpkin.fr>
Date: Tue, 23 Dec 2025 19:41:24 +0100
Subject: [PATCH 1/2] using a unique low level semaphore to prevent
 simultaneous access to pixel data

---
 src/main.cpp | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index 64f3529d..9e710b9b 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -114,8 +114,7 @@ ModuleLiveScripts moduleLiveScripts = ModuleLiveScripts(&server, &esp32sveltekit
 ModuleChannels moduleChannels = ModuleChannels(&server, &esp32sveltekit);
 ModuleMoonLightInfo moduleMoonLightInfo = ModuleMoonLightInfo(&server, &esp32sveltekit);
 
-volatile xSemaphoreHandle effectSemaphore = xSemaphoreCreateBinary();
-volatile xSemaphoreHandle driverSemaphore = xSemaphoreCreateBinary();
+volatile xSemaphoreHandle lowLevelSemaphore = xSemaphoreCreateBinary();
 
 TaskHandle_t effectTaskHandle = NULL;
 TaskHandle_t driverTaskHandle = NULL;
@@ -128,7 +127,7 @@ void effectTask(void* pvParameters) {
   for (;;) {
     esp32sveltekit.lps++;  // 🌙 todo: not moonlight specific?
 
-    if (xSemaphoreTake(effectSemaphore, pdMS_TO_TICKS(100)) == pdFALSE) {
+    if (xSemaphoreTake(lowLevelSemaphore, pdMS_TO_TICKS(100)) == pdFALSE) {
       // EXT_LOGW(ML_TAG, "effectSemaphore wait too long"); //happens if no driver!, but let effects continue (for monitor) at 10 fps
     }
 
@@ -140,7 +139,7 @@ void effectTask(void* pvParameters) {
       layerP.loop20ms();
     }
 
-    xSemaphoreGive(driverSemaphore);
+    xSemaphoreGive(lowLevelSemaphore);
 
     vTaskDelay(1);  // yield to other tasks, 1 tick (~1ms)
   }
@@ -152,11 +151,11 @@ void driverTask(void* pvParameters) {
   // layerP.setup() done in effectTask
 
   for (;;) {
-    xSemaphoreTake(driverSemaphore, pdMS_TO_TICKS(100));
+    xSemaphoreTake(lowLevelSemaphore, pdMS_TO_TICKS(100));
 
     layerP.loopDrivers();
 
-    xSemaphoreGive(effectSemaphore);
+    xSemaphoreGive(lowLevelSemaphore);
 
     vTaskDelay(1);  // yield to other tasks, 1 tick (~1ms)
   }
@@ -325,8 +324,6 @@ void setup() {
       false);
     #endif
 
-  xSemaphoreGive(effectSemaphore);  // Allow effectTask to run first
-
   // 🌙
   xTaskCreateUniversal(effectTask,                          // task function
                        "AppEffectTask",                     // name

From bca999117c22828ba2a6dee2437bb4965e4bb18a Mon Sep 17 00:00:00 2001
From: limpkin <limpkin@limpkin.fr>
Date: Tue, 23 Dec 2025 20:24:23 +0100
Subject: [PATCH 2/2] actually use semaphores for what they're intended

---
 src/main.cpp | 30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index 9e710b9b..8a143488 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -129,18 +129,20 @@ void effectTask(void* pvParameters) {
 
     if (xSemaphoreTake(lowLevelSemaphore, pdMS_TO_TICKS(100)) == pdFALSE) {
       // EXT_LOGW(ML_TAG, "effectSemaphore wait too long"); //happens if no driver!, but let effects continue (for monitor) at 10 fps
+      //EXT_LOGW(ML_TAG, "effect: semaphore wait too long");
     }
+    else {
+      layerP.loop();  // run all the effects of all virtual layers (currently only one layer)
 
-    layerP.loop();  // run all the effects of all virtual layers (currently only one layer)
+      static unsigned long last20ms = 0;
+      if (millis() - last20ms >= 20) {
+        last20ms = millis();
+        layerP.loop20ms();
+      }
 
-    static unsigned long last20ms = 0;
-    if (millis() - last20ms >= 20) {
-      last20ms = millis();
-      layerP.loop20ms();
+      xSemaphoreGive(lowLevelSemaphore);
     }
 
-    xSemaphoreGive(lowLevelSemaphore);
-
     vTaskDelay(1);  // yield to other tasks, 1 tick (~1ms)
   }
 }
@@ -151,12 +153,14 @@ void driverTask(void* pvParameters) {
   // layerP.setup() done in effectTask
 
   for (;;) {
-    xSemaphoreTake(lowLevelSemaphore, pdMS_TO_TICKS(100));
-
-    layerP.loopDrivers();
-
-    xSemaphoreGive(lowLevelSemaphore);
+    if (xSemaphoreTake(lowLevelSemaphore, pdMS_TO_TICKS(100))  == pdFALSE) {
+      //EXT_LOGW(ML_TAG, "driver: semaphore wait too long");
+    }
+    else {
+      layerP.loopDrivers();
 
+      xSemaphoreGive(lowLevelSemaphore);
+    }
     vTaskDelay(1);  // yield to other tasks, 1 tick (~1ms)
   }
 }
@@ -324,6 +328,8 @@ void setup() {
       false);
     #endif
 
+  xSemaphoreGive(lowLevelSemaphore);
+
   // 🌙
   xTaskCreateUniversal(effectTask,                          // task function
                        "AppEffectTask",                     // name