Added "temperature_sender.cpp" to examples

examples/temperature_sender.cpp

@@ -0,0 +1,64 @@
+#include <Arduino.h>
+
+#include "sensesp_app.h"
+#include "transforms/linear.h"
+#include "devices/analog_input.h"
+
+#include "transforms/analogvoltage.h"
+#include "transforms/voltagedividerR2.h"
+#include "transforms/temperatureinterpreter.h"
+
+// SensESP builds upon the ReactESP framework. Every ReactESP application
+// defines an "app" object vs defining a "main()" method.
+ReactESP app([] () {
+
+  // Some initialization boilerplate when in debug mode...
+  #ifndef SERIAL_DEBUG_DISABLED
+  Serial.begin(115200);
+
+  // A small arbitrary delay is required to let the
+  // serial port catch up
+
+  delay(1000);
+  Debug.setSerialEnabled(true);
+  #endif
+
+  // Create the global SensESPApp() object.
+  sensesp_app = new SensESPApp();
+
+
+  // The "SignalK path" identifies this sensor to the SignalK network. Leaving
+  // this blank would indicate this particular sensor (or transform) does not
+  // broadcast SignalK data
+  const char* sk_path = "electrical.generator.engine.water.temp";
+
+
+  // A blank sk path means you do not want any SignalK generated from that
+  // particular transform...
+  const char* no_sk_wanted = "";
+
+
+  // Connecting a "sender" to the MCU involves using a "voltage divider" circuit. A resistor (R1) is connected
+  // to the voltage output of the board (3.3v or 5v, specified in Vin) to an intersection of two wires.  One
+  // wire connects to the AnalogInput pin of the MCU, and the other wire connects to the sending
+  // unit doing the measurement. The sender is itself a variable resistor that is then connected to ground, forming
+  // the "R2" of a voltage divider circuit. The transform "VoltageDividerR2" can take a known
+  // voltage in, resistance R1, and based on the current voltage read from AnalogInput, compute
+  // the current resistance of the sender (R2).
+  const float Vin = 3.3; // Voltage sent into the voltage divider circuit that includes the analog sender
+  const float R1 = 51.0; // The resistance, in ohms, of the R1 resitor in the analog sender divider circuit
+
+  auto* pAnalogInput = new AnalogInput();
+
+  // Translating the number returned by AnalogInput into a temperature requires several transformations.
+  // Wire them up in sequence...
+  pAnalogInput->connectTo(new AnalogVoltage()) ->
+                connectTo(new VoltageDividerR2(R1, Vin, no_sk_wanted, "/gen/temp/sender")) ->
+                connectTo(new TemperatureInterpreter(no_sk_wanted, "/gen/temp/curve")) ->
+                connectTo(new Linear(sk_path, 1.0, 0.0, "/gen/temp/adjust"));
+
+
+  // Start the SensESP application running
+  sensesp_app->enable();
+
+});