Improve power saving (#1024)

* Limit tasks in loop based on voltage

* Updated disconnect voltage limit

* Fixed 8266 build

lib/AmsMqttHandler/src/AmsMqttHandler.cpp

@@ -166,7 +166,7 @@ bool AmsMqttHandler::connected() {
 
 bool AmsMqttHandler::loop() {
     bool ret = mqtt.loop();
-    delay(10);
+	delay(10); // Needed to preserve power. After adding this, the voltage is super smooth on a HAN powered device
     yield();
 	#if defined(ESP32)
 		esp_task_wdt_reset();

lib/HwTools/include/HwTools.h

@@ -67,7 +67,9 @@ private:
     bool ledInvert, rgbInvert;
     uint8_t vccPin, vccGnd_r, vccVcc_r;
     float vccOffset, vccMultiplier;
+    float vcc = 3.3; // Last known Vcc
     float maxVcc = 3.25; // Best to have this close to max as a start, in case Pow-U reboots and starts off with a low voltage, we dont want that to be perceived as max
+    unsigned long lastVccRead = 0;
 
     uint16_t analogRange = 1024;
     AdcConfig voltAdc, tempAdc;

lib/HwTools/src/HwTools.cpp

@@ -654,8 +654,12 @@ bool HwTools::writeLedPin(uint8_t color, uint8_t state) {
 }
 
 bool HwTools::isVoltageOptimal(float range) {
-	if(boardType >= 5 && boardType <= 7 && maxVcc > 2.8) { // Pow-*
-		float vcc = getVcc();
+	if(boardType >= 1 && boardType <= 8 && maxVcc > 2.8) { // BUS-Power boards
+        unsigned long now = millis();
+        if(now - lastVccRead > 250) {
+		    vcc = getVcc();
+            lastVccRead = now;
+        }
 		if(vcc > 3.4 || vcc < 2.8) {
 			maxVcc = 0; // Voltage is outside the operating range, we have to assume voltage is OK
 		} else if(vcc > maxVcc) {