From 70d3bcfd2a9a65b23290ba47c23e0bcbeb58eee1 Mon Sep 17 00:00:00 2001
From: Sebastian Nieto <sebanieto@gmail.com>
Date: Mon, 7 Sep 2026 21:27:30 -0300
Subject: [PATCH] Implement smooth non-blocking backlight fade for day/night
 transitions

---
 sketch/obd2_gauge/meter.h        | 55 +++++++++++++++++++++++---------
 sketch/obd2_gauge/obd2_gauge.ino |  2 ++
 2 files changed, 42 insertions(+), 15 deletions(-)

diff --git a/sketch/obd2_gauge/meter.h b/sketch/obd2_gauge/meter.h
index ca7145a..dca5201 100644
--- a/sketch/obd2_gauge/meter.h
+++ b/sketch/obd2_gauge/meter.h
@@ -801,37 +801,62 @@ void updateMeter(uint8_t pidNo, String response) { // update parameter on screen
 }
 /*-------------------------------*/
 
+// Target and current brightness variables for smooth fade
+uint8_t targetBacklight = 255;
+float currentBacklight = 255.0f;
+uint32_t lastBacklightStepTime = 0;
+
+void updateBacklightFade() {
+  uint32_t now = millis();
+  if (now - lastBacklightStepTime >= 15) { // every 15ms step
+    lastBacklightStepTime = now;
+    if (abs(currentBacklight - (float)targetBacklight) > 0.5f) {
+      if (currentBacklight < targetBacklight) {
+        currentBacklight += 3.0f;
+        if (currentBacklight > targetBacklight)
+          currentBacklight = targetBacklight;
+      } else {
+        currentBacklight -= 3.0f;
+        if (currentBacklight < targetBacklight)
+          currentBacklight = targetBacklight;
+      }
+      ledcWrite(backlightChannel, (uint32_t)currentBacklight);
+    }
+  }
+}
+
 // auto dim backlight function
 void autoDim() {
   int light = analogRead(LDR_PIN); // read light
-  if (light > LIGHT_LEVEL) {       // low light
+  if (light > LIGHT_LEVEL) {       // low light (dark)
     low_count++;
-    if (low_count > 10) {
-      low_count = 10; // low amb light 10 times count
+    if (low_count > 6) {
+      low_count = 6;
       if (!dim) {
-        ledcWrite(backlightChannel, 50); // dim light
+        targetBacklight = 50; // smooth fade target: dim
         dim = true;
 #ifdef SERIAL_DEBUG
-        Serial.println(F("Backlight -> dim"));
+        Serial.println(F("Backlight -> target dim (50)"));
 #endif
-      } // if !dim
-    } // if low_count
+      }
+    }
     high_count = 0;
 
-  } else {
+  } else { // bright light (day)
     high_count++;
-    if (high_count > 10) {
-      high_count = 10; // high amb light 10 times count
+    if (high_count > 6) {
+      high_count = 6;
       if (dim) {
-        ledcWrite(backlightChannel, 255); // brightest
+        targetBacklight = 255; // smooth fade target: bright
         dim = false;
 #ifdef SERIAL_DEBUG
-        Serial.println(F("Backlight -> bright"));
+        Serial.println(F("Backlight -> target bright (255)"));
 #endif
-      } // if dim
-    } // if high_count
+      }
+    }
     low_count = 0;
-  } // if light > lightlevel
+  }
+  updateBacklightFade();
 } // autodim
 //---------------------------
 /*############################################*/
diff --git a/sketch/obd2_gauge/obd2_gauge.ino b/sketch/obd2_gauge/obd2_gauge.ino
index b67fc28..640ba0c 100644
--- a/sketch/obd2_gauge/obd2_gauge.ino
+++ b/sketch/obd2_gauge/obd2_gauge.ino
@@ -413,6 +413,8 @@ recent_client_addr : {0x00,0x00,0x00,0x00,0x00,0x00} array of bytes[6]
 
 /*###################################*/
 void loop() {
+  updateBacklightFade(); // non-blocking smooth backlight fade handler
+
   // SCAN TOUCHSCREEN & BUTTON
   // - Single click on a quadrant: toggles between clock (arc) and number
   // - Double click on a quadrant: puts that instrument in full screen (or exits full screen)