From ec78af6beaf98f13898a7650fb63057f10defa04 Mon Sep 17 00:00:00 2001
From: Nicolae Hodos <nicu.hodos@gmail.com>
Date: Sun, 29 Jan 2017 12:04:57 +0100
Subject: [PATCH] send voltage information

---
 water_sensor/water_sensor.ino | 40 +++++++++++++++++++++++++++++------
 1 file changed, 33 insertions(+), 7 deletions(-)

diff --git a/water_sensor/water_sensor.ino b/water_sensor/water_sensor.ino
index 447433b..178b05c 100644
--- a/water_sensor/water_sensor.ino
+++ b/water_sensor/water_sensor.ino
@@ -13,9 +13,9 @@
 #define SENDER 2
 #define CONTROLLER 4
 
+#define SENSOR_ID 3
+
 RCSwitch mySwitch = RCSwitch();
-char* CIRCUIT_OPEN  =  "00000000000000000000000001000011";
-char* CIRCUIT_CLOSED = "00000000000000000000000001100011";
 
 int counter = 0;
 
@@ -48,11 +48,11 @@ bool readState() {
 }
 
 void sendWindowState() {
-  if (readState()) {
-    mySwitch.send(CIRCUIT_OPEN);
-  } else {
-    mySwitch.send(CIRCUIT_CLOSED);
-  }
+  unsigned long value = 0x70000000;
+  value |= readVcc() << 6;
+  value |= !readState() << 5;
+  value |= SENSOR_ID;
+  mySwitch.send(value, 32);
 }
 
 void sleep() {
@@ -96,3 +96,29 @@ void enableWdt()
     WDTCR = _BV(WDIE) | _BV(WDP3) | _BV(WDP0);    //8192ms
 }
 
+long readVcc() {
+  // Read 1.1V reference against AVcc
+  // set the reference to Vcc and the measurement to the internal 1.1V reference
+  #if defined(__AVR_ATmega32U4__) || defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
+    ADMUX = _BV(REFS0) | _BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
+  #elif defined (__AVR_ATtiny24__) || defined(__AVR_ATtiny44__) || defined(__AVR_ATtiny84__)
+    ADMUX = _BV(MUX5) | _BV(MUX0);
+  #elif defined (__AVR_ATtiny25__) || defined(__AVR_ATtiny45__) || defined(__AVR_ATtiny85__)
+    ADMUX = _BV(MUX3) | _BV(MUX2);
+  #else
+    ADMUX = _BV(REFS0) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
+  #endif
+
+  delay(2); // Wait for Vref to settle
+  ADCSRA |= _BV(ADSC); // Start conversion
+  while (bit_is_set(ADCSRA,ADSC)); // measuring
+
+  uint8_t low  = ADCL; // must read ADCL first - it then locks ADCH
+  uint8_t high = ADCH; // unlocks both
+
+  long result = (high<<8) | low;
+
+  result = 1125300L / result; // Calculate Vcc (in mV); 1125300 = 1.1*1023*1000
+  return result; // Vcc in millivolts
+}
+