Update Usermod: Battery

Issue:
When taking the initial voltage reading after first powering on, voltage hasn't had chance to stabilize so the reading can be inaccurate, which in turn may incorrectly trigger the low-power preset. (Manifests when the user has selected a low read interval and/or is using a capacitor).

Resolution:
A non-blocking, fixed 10 second delay has been added to the initial voltage reading to give the voltage time to stabilize.

This is a reworked version of the (now closed) PR here:
https://github.com/Aircoookie/WLED/pull/3959

- Rebased the update for 0_15.

- Added a constant so the delay can be modified via my_config.h.

- Small adjustments to make the PR compatible again after the recent restructuring in this PR: (https://github.com/Aircoookie/WLED/pull/3003).

Thankyou!

usermods/Battery/battery_defaults.h

@@ -14,6 +14,12 @@
   #endif
 #endif
 
+// The initial delay before the first battery voltage reading after power-on.
+// This allows the voltage to stabilize before readings are taken, improving accuracy of initial reading.
+#ifndef USERMOD_BATTERY_INITIAL_DELAY
+  #define USERMOD_BATTERY_INITIAL_DELAY 10000 // (milliseconds)
+#endif
+
 // the frequency to check the battery, 30 sec
 #ifndef USERMOD_BATTERY_MEASUREMENT_INTERVAL
   #define USERMOD_BATTERY_MEASUREMENT_INTERVAL 30000

usermods/Battery/readme.md

@@ -37,6 +37,7 @@ define `USERMOD_BATTERY` in `wled00/my_config.h`
 | ----------------------------------------------- | ----------- |-------------------------------------------------------------------------------------- |
 | `USERMOD_BATTERY`                               |             | define this (in `my_config.h`) to have this usermod included wled00\usermods_list.cpp |
 | `USERMOD_BATTERY_MEASUREMENT_PIN`               |             | defaults to A0 on ESP8266 and GPIO35 on ESP32                                         |
+| `USERMOD_BATTERY_INITIAL_DELAY`                 | ms          | delay before initial reading. defaults to 10 seconds to allow voltage stabilization
 | `USERMOD_BATTERY_MEASUREMENT_INTERVAL`          | ms          | battery check interval. defaults to 30 seconds                                        |
 | `USERMOD_BATTERY_{TYPE}_MIN_VOLTAGE`            | v           | minimum battery voltage. default is 2.6 (18650 battery standard)                      |
 | `USERMOD_BATTERY_{TYPE}_MAX_VOLTAGE`            | v           | maximum battery voltage. default is 4.2 (18650 battery standard)                      |
@@ -88,6 +89,10 @@ Specification from:  [Molicel INR18650-M35A, 3500mAh 10A Lithium-ion battery, 3.
 
 2024-04-30
 
+- improved initial reading accuracy by delaying initial measurement to allow voltage to stabilize at power-on
+
+2024-04-30
+
 - integrate factory pattern to make it easier to add other / custom battery types
 - update readme
 

usermods/Battery/usermod_v2_Battery.h

@@ -22,6 +22,10 @@ class UsermodBattery : public Usermod
     UMBattery* bat = new UnkownUMBattery();
     batteryConfig cfg;
 
+    // Initial delay before first reading to allow voltage stabilization
+    unsigned long initialDelay = USERMOD_BATTERY_INITIAL_DELAY;
+    bool initialDelayComplete = false;
+    bool isFirstVoltageReading = true;
     // how often to read the battery voltage
     unsigned long readingInterval = USERMOD_BATTERY_MEASUREMENT_INTERVAL;
     unsigned long nextReadTime = 0;
@@ -137,7 +141,6 @@ class UsermodBattery : public Usermod
           if (pinManager.allocatePin(batteryPin, false, PinOwner::UM_Battery)) {
             DEBUG_PRINTLN(F("Battery pin allocation succeeded."));
             success = true;
-            bat->setVoltage(readVoltage());
           }
 
         if (!success) {
@@ -148,10 +151,10 @@ class UsermodBattery : public Usermod
         }
       #else //ESP8266 boards have only one analog input pin A0
         pinMode(batteryPin, INPUT);
-        bat->setVoltage(readVoltage());
       #endif
 
-      nextReadTime = millis() + readingInterval;
+      // First voltage reading is delayed to allow voltage stabilization after powering up
+      nextReadTime = millis() + initialDelay;
       lastReadTime = millis();
 
       initDone = true;
@@ -178,6 +181,25 @@ class UsermodBattery : public Usermod
 
       lowPowerIndicator();
 
+      // Handling the initial delay
+      if (!initialDelayComplete && millis() < nextReadTime)
+        return; // Continue to return until the initial delay is over
+
+      // Once the initial delay is over, set it as complete
+      if (!initialDelayComplete)
+        {
+          initialDelayComplete = true;
+          // Set the regular interval after initial delay
+          nextReadTime = millis() + readingInterval;
+        }
+
+      // Make the first voltage reading after the initial delay has elapsed
+      if (isFirstVoltageReading)
+        {
+          bat->setVoltage(readVoltage());
+          isFirstVoltageReading = false;
+        }
+
       // check the battery level every USERMOD_BATTERY_MEASUREMENT_INTERVAL (ms)
       if (millis() < nextReadTime) return;