Fix: output-glitching on ESPNow remote command reception

Processing of received button command is no longer processed in the callback, instead the value is saved to a variable and processed in the main loop.
The actual fix is to not access the file system while data is being sent out: even just trying to open a non-existing file causes glitches on the C3. Waiting for the bus to finish fixes this BUT it causes a frame-delay which is the lesser evil than random color flashes.

wled00/fcn_declare.h

@@ -231,6 +231,7 @@ bool getPresetName(byte index, String& name);
 
 //remote.cpp
 void handleRemote(uint8_t *data, size_t len);
+void processESPNowButton();
 
 //set.cpp
 bool isAsterisksOnly(const char* str, byte maxLen);

wled00/remote.cpp

@@ -1,6 +1,8 @@
 #include "wled.h"
 #ifndef WLED_DISABLE_ESPNOW
 
+#define ESPNOW_BUSWAIT_TIMEOUT 30 // timeout in ms to wait for bus to finish updating
+
 #define NIGHT_MODE_DEACTIVATED     -1
 #define NIGHT_MODE_BRIGHTNESS      5
 
@@ -38,6 +40,7 @@ typedef struct WizMoteMessageStructure {
 
 static uint32_t last_seq = UINT32_MAX;
 static int brightnessBeforeNightMode = NIGHT_MODE_DEACTIVATED;
+static uint8_t ESPNowButton = 0; // set in callback if new button value is received
 
 // Pulled from the IR Remote logic but reduced to 10 steps with a constant of 3
 static const byte brightnessSteps[] = {
@@ -121,6 +124,9 @@ static bool remoteJson(int button)
 
   sprintf_P(objKey, PSTR("\"%d\":"), button);
 
+  unsigned long start = millis();
+  while (strip.isUpdating() && millis()-start < ESPNOW_BUSWAIT_TIMEOUT) yield(); // wait for strip to finish updating, accessing FS during sendout causes glitches
+
   // attempt to read command from remote.json
   readObjectFromFile(PSTR("/remote.json"), objKey, pDoc);
   JsonObject fdo = pDoc->as<JsonObject>();
@@ -202,8 +208,14 @@ void handleRemote(uint8_t *incomingData, size_t len) {
   DEBUG_PRINT(F("] button: "));
   DEBUG_PRINTLN(incoming->button);
 
-  if (!remoteJson(incoming->button))
+  ESPNowButton = incoming->button; // save state, do not process in callback (can cause glitches)
-    switch (incoming->button) {
+  last_seq = cur_seq;
+}
+
+void processESPNowButton() {
+  if(ESPNowButton > 0) {
+  if (!remoteJson(ESPNowButton))
+    switch (ESPNowButton) {
       case WIZMOTE_BUTTON_ON             : setOn();                                         break;
       case WIZMOTE_BUTTON_OFF            : setOff();                                        break;
       case WIZMOTE_BUTTON_ONE            : presetWithFallback(1, FX_MODE_STATIC,        0); break;
@@ -219,7 +231,8 @@ void handleRemote(uint8_t *incomingData, size_t len) {
       case WIZ_SMART_BUTTON_BRIGHT_DOWN  : brightnessDown();                                break;
       default: break;
     }
-  last_seq = cur_seq;
+  }
+  ESPNowButton = 0;
 }
 
 #else

wled00/wled.cpp

@@ -84,6 +84,9 @@ void WLED::loop()
   #ifndef WLED_DISABLE_INFRARED
   handleIR();
   #endif
+  #ifndef WLED_DISABLE_ESPNOW
+  processESPNowButton();
+  #endif
   #ifndef WLED_DISABLE_ALEXA
   handleAlexa();
   #endif