From f0974e6e79026b54ed5f78a92d2e086cab4abd4a Mon Sep 17 00:00:00 2001
From: klaute <klaute@web.de>
Date: Mon, 28 Jan 2019 10:54:16 +0000
Subject: [PATCH] Update 'firmware/sensors.ino'

Comments comments comments
---
 firmware/sensors.ino | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/firmware/sensors.ino b/firmware/sensors.ino
index dc5479f..820650c 100755
--- a/firmware/sensors.ino
+++ b/firmware/sensors.ino
@@ -53,8 +53,12 @@ float fetchWindspeed() {
 // Copied from https://arduinodiy.wordpress.com/2016/12/25/monitoring-lipo-battery-voltage-with-wemos-d1-minibattery-shield-and-thingspeak/
 #ifdef BATTERY_POWERED
 float getBatteryVoltage() {
+  // ESP8266 ADC pin input voltage range ist 0V .. 1V
+  // The Wemos D1 mini does already contain a voltage divider circuit: A0(Wemos PCB) -- [220kOhm] -- ADC (ESP8266)-- [100kOhm] -- GND
+  // The (+) pole of the battery is connected to the A0 pin of the Wemos board through a additional 100kOhm resistance.
+  // The battery voltage of 4.2V max is measured as 1.0V on ESP8266 ADC pin.
   uint16_t raw = analogRead(A0);
   float volt = raw / 1023.0;
   return volt * 4.2;
 }
-#endif
+#endif