Temphum si7021 (mysensors#33)

* Added Si7021 temphum sketch

* Added Vcc library

Author: Yveaux

examples/Si7021TemperatureAndHumiditySensor/Si7021TemperatureAndHumiditySensor.ino

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+/**
+ * The MySensors Arduino library handles the wireless radio link and protocol
+ * between your home built sensors/actuators and HA controller of choice.
+ * The sensors forms a self healing radio network with optional repeaters. Each
+ * repeater and gateway builds a routing tables in EEPROM which keeps track of the
+ * network topology allowing messages to be routed to nodes.
+ *
+ * Created by Henrik Ekblad <[email protected]>
+ * Copyright (C) 2013-2015 Sensnology AB
+ * Full contributor list: https://github.com/mysensors/Arduino/graphs/contributors
+ *
+ * Documentation: http://www.mysensors.org
+ * Support Forum: http://forum.mysensors.org
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ *******************************
+ *
+ * REVISION HISTORY
+ * Version 1.0: Yveaux
+ * 
+ * DESCRIPTION
+ * This sketch provides an example of how to implement a humidity/temperature
+ * sensor using a Si7021 sensor.
+ *  
+ * For more information, please visit:
+ * http://www.mysensors.org/build/humiditySi7021
+ * 
+ */
+
+// Enable debug prints
+#define MY_DEBUG
+
+// Enable REPORT_BATTERY_LEVEL to measure battery level and send changes to gateway
+//#define REPORT_BATTERY_LEVEL
+
+// Enable and select radio type attached 
+#define MY_RADIO_NRF24
+//#define MY_RADIO_RFM69
+//#define MY_RS485
+
+#include <MySensors.h>  
+
+#define CHILD_ID_HUM  0
+#define CHILD_ID_TEMP 1
+
+static bool metric = true;
+
+// Sleep time between sensor updates (in milliseconds)
+static const uint64_t UPDATE_INTERVAL = 60000;
+
+#include <SI7021.h>
+static SI7021 sensor;
+
+#ifdef REPORT_BATTERY_LEVEL
+#include <Vcc.h>
+static uint8_t oldBatteryPcnt = 200;  // Initialize to 200 to assure first time value will be sent.
+const float VccMin        = 1.8;      // Minimum expected Vcc level, in Volts: Brownout at 1.8V    -> 0%
+const float VccMax        = 2.0*1.6;  // Maximum expected Vcc level, in Volts: 2xAA fresh Alkaline -> 100%
+const float VccCorrection = 1.0;      // Measured Vcc by multimeter divided by reported Vcc
+static Vcc vcc(VccCorrection); 
+#endif
+
+void presentation()  
+{ 
+  // Send the sketch info to the gateway
+  sendSketchInfo("TemperatureAndHumidity", "1.0");
+
+  // Present sensors as children to gateway
+  present(CHILD_ID_HUM, S_HUM,   "Humidity");
+  present(CHILD_ID_TEMP, S_TEMP, "Temperature");
+
+  metric = getControllerConfig().isMetric;
+}
+
+void setup()
+{
+  while (not sensor.begin())
+  {
+    Serial.println(F("Sensor not detected!"));
+    delay(5000);
+  }
+}
+
+
+void loop()      
+{  
+  // Read temperature & humidity from sensor.
+  const float temperature = float( metric ? sensor.getCelsiusHundredths() : sensor.getFahrenheitHundredths() ) / 100.0;
+  const float humidity    = float( sensor.getHumidityBasisPoints() ) / 100.0;
+
+#ifdef MY_DEBUG
+  Serial.print(F("Temp "));
+  Serial.print(temperature);
+  Serial.print(metric ? 'C' : 'F');
+  Serial.print(F("\tHum "));
+  Serial.println(humidity);
+#endif
+
+  static MyMessage msgHum( CHILD_ID_HUM,  V_HUM );
+  static MyMessage msgTemp(CHILD_ID_TEMP, V_TEMP);
+
+  send(msgTemp.set(temperature, 2));
+  send(msgHum.set(humidity, 2));
+
+#ifdef REPORT_BATTERY_LEVEL
+  const uint8_t batteryPcnt = static_cast<uint8_t>(0.5 + vcc.Read_Perc(VccMin, VccMax));
+
+#ifdef MY_DEBUG
+  Serial.print(F("Vbat "));
+  Serial.print(vcc.Read_Volts());
+  Serial.print(F("\tPerc "));
+  Serial.println(batteryPcnt);
+#endif
+
+  // Battery readout should only go down. So report only when new value is smaller than previous one.
+  if ( batteryPcnt < oldBatteryPcnt )
+  {
+      sendBatteryLevel(batteryPcnt);
+      oldBatteryPcnt = batteryPcnt;
+  }
+#endif
+
+  // Sleep until next update to save energy
+  sleep(UPDATE_INTERVAL); 
+}

libraries/Vcc/.gitignore

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+# Compiled Object files
+*.slo
+*.lo
+*.o
+*.obj
+
+# Compiled Dynamic libraries
+*.so
+*.dylib
+*.dll
+
+# Compiled Static libraries
+*.lai
+*.la
+*.a
+*.lib
+
+# Executables
+*.exe
+*.out
+*.app