From c685867d51272bd4f2de1d80015ea197009152a4 Mon Sep 17 00:00:00 2001
From: Stefan Ostermann <stefan@ostermail.de>
Date: Sun, 4 Apr 2021 18:42:39 +0200
Subject: [PATCH] battery sensor

---
 receiver-arduino/receiver-arduino.ino   | 11 ++++-
 sensor433-arduino/sensor433-arduino.ino | 56 ++++++++++++++++++-------
 2 files changed, 50 insertions(+), 17 deletions(-)

diff --git a/receiver-arduino/receiver-arduino.ino b/receiver-arduino/receiver-arduino.ino
index 4adfe63..712542d 100644
--- a/receiver-arduino/receiver-arduino.ino
+++ b/receiver-arduino/receiver-arduino.ino
@@ -14,12 +14,12 @@ RH_ASK driver(RH_SPEED, RH_RX_PIN);
 
 float t = 0;
 float h = 0;
-uint8_t bat_percent = 0;
-uint8_t bat_raw = 0;
+long bat = 0;
 
 #define MSG_START 0x00
 #define MSG_TEMP 0x01
 #define MSG_HUMID 0x02
+#define MSG_BAT 0x03
 #define MSG_ERR 0xee
 
 void setup() {
@@ -55,6 +55,13 @@ void loop() {
           Serial.print(t);
           Serial.print("%");
           break;
+        case MSG_BAT:
+          // battery data
+          Serial.println("0x03 Battery");
+          memcpy(&bat, &rh_buf[1], 4);
+          Serial.print(bat);
+          Serial.print("mV");
+          break;          
         case MSG_ERR:
           // error
           Serial.println("0xEE error");
diff --git a/sensor433-arduino/sensor433-arduino.ino b/sensor433-arduino/sensor433-arduino.ino
index c77cce8..353fe6b 100644
--- a/sensor433-arduino/sensor433-arduino.ino
+++ b/sensor433-arduino/sensor433-arduino.ino
@@ -2,7 +2,7 @@
    RadioHead attiny85 DHT22 Weather Station
 
    2021 Stefan Ostermann based on several source from the internetz.
-   
+
    Sources:
    https://git.cryhost.de/crycode/attiny85-radiohead-dht22-weather-sensor/-/tree/master
 */
@@ -63,6 +63,7 @@ uint8_t rh_buf[RH_BUF_LEN] = { 0x00, 0x00, 0x00, 0x00, 0x00 };
 #define MSG_START 0x00
 #define MSG_TEMP 0x01
 #define MSG_HUMID 0x02
+#define MSG_BAT 0x03
 #define MSG_ERR 0xee
 
 
@@ -72,11 +73,13 @@ RH_ASK rh_driver(RH_SPEED, RH_RX_PIN, RH_TX_PIN, RH_PTT_PIN);
 volatile boolean f_wdt = 1;
 
 // temp / humid toggle
-volatile boolean toggle = 0;
+volatile uint8_t counter = 0;
 
 
 void gotoSleep(void);
 
+int getVcc();
+
 void setup() {
   // setup the LED pin
   pinMode(LED_PIN, OUTPUT);
@@ -118,28 +121,29 @@ void loop() {
     // temperature and humidity
     float t = 0;//float is 32bit = 1byte
     float h = 0;
+    long battery = 0;
 
-    // read from the sensor and check if it was successfull
-    if (dht_read_data(&dht, &t, &h) == 1) {
-      // normal message
-
-      if (toggle) {
+    if (counter % 4 == 0) {
+        rh_buf[0] = MSG_BAT;
+        battery = getVcc();
+        memcpy(&rh_buf[1], &battery, 4);
+        rh_send(RH_BUF_LEN);
+     }else if (dht_read_data(&dht, &t, &h) == 1) {
+      if (counter % 2 == 0) {
         rh_buf[0] = MSG_TEMP;
         memcpy(&rh_buf[1], &t, 4);
-      } else {
+      } else if (counter % 2 == 1) {
         rh_buf[0] = MSG_HUMID;
-        memcpy(&rh_buf[1],&h,4);
+        memcpy(&rh_buf[1], &h, 4);
       }
-      toggle = !toggle;
-
-      rh_send(RH_BUF_LEN);
-
+      rh_send(RH_BUF_LEN);  
     } else {
       // error message
       rh_buf[0] = MSG_ERR;
       rh_send(1);
 
     }
+    counter++;
 
     // turn off the LED
     digitalWrite(LED_PIN, LOW);
@@ -167,7 +171,7 @@ ISR(WDT_vect)
    system wakes up when watchdog is timed out
 */
 void system_sleep() {
-  cbi(ADCSRA, ADEN);                   // switch Analog to Digitalconverter OFF
+  //cbi(ADCSRA, ADEN);                   // switch Analog to Digitalconverter OFF
 
   set_sleep_mode(SLEEP_MODE_PWR_DOWN); // sleep mode is set here
   sleep_enable();
@@ -175,7 +179,7 @@ void system_sleep() {
   sleep_mode();                        // System sleeps here
 
   sleep_disable();                     // System continues execution here when watchdog timed out
-  sbi(ADCSRA, ADEN);                   // switch Analog to Digitalconverter ON
+  //sbi(ADCSRA, ADEN);                   // switch Analog to Digitalconverter ON
 }
 
 /* 0=16ms, 1=32ms,2=64ms,3=128ms,4=250ms,5=500ms
@@ -198,3 +202,25 @@ void setup_watchdog(int ii) {
   WDTCR = bb;
   WDTCR |= _BV(WDIE);
 }
+
+
+/**
+   From https://github.com/cano64/ArduinoSystemStatus/blob/master/SystemStatus.cpp
+*/
+int getVcc() {
+  //reads internal 1V1 reference against VCC
+  ADMUX = _BV(MUX3) | _BV(MUX2); // For ATtiny85/45
+
+  _delay_ms(5);; // Wait for Vref to settle
+  ADCSRA |= _BV(ADSC); // Convert
+  while (bit_is_set(ADCSRA, ADSC));
+  uint8_t low = ADCL;
+  unsigned int val = (ADCH << 8) | low;
+  //discard previous result
+  ADCSRA |= _BV(ADSC); // Convert
+  while (bit_is_set(ADCSRA, ADSC));
+  low = ADCL;
+  val = (ADCH << 8) | low;
+
+  return ((long)1024 * 1100) / val;
+}