ArduinoEventHub

tempmeter.ino

#include <Process.h>
 
const int sensorPin = A0;
const int greenLedPin = 4;
const int redLedPin = 2;
// the HTTP status that we expect back from the Event Hub
const char okHttpStatus[] = "201";
   
void setup() {  
  pinMode(greenLedPin, OUTPUT);
  pinMode(redLedPin, OUTPUT);
   
  // turn the LED on (HIGH is the voltage level)
  digitalWrite(greenLedPin, HIGH);
  // turn the LED on (HIGH is the voltage level)
  digitalWrite(redLedPin, HIGH);     
 
  Bridge.begin();   // Initialize the Bridge
  Serial.begin(9600);   // Initialize the Serial
}
 
void loop() {
  // turn the LED off (LOW is the voltage level)
  digitalWrite(greenLedPin, LOW);
  // turn the LED off (LOW is the voltage level)
  digitalWrite(redLedPin, LOW);  
   
  // read the value on AnalogIn pin 0 and store it in a variable
  int sensorVal = analogRead(sensorPin);
 
  // convert the ADC reading to voltage, 
  // somehow the Yun gives me only 4.5V instead of 5V
  float voltage = (sensorVal / 1024.0) * 4.5;
 
  // convert the voltage to temperature in degrees C, 
  // the sensor changes 10 mV per degree
  float temperature = (voltage - .5) * 100;
 
  Process p;
  // Run the python script with the temperature and device ID 
  // as parameters
  String cmd = "python /root/sendtoeventhub.py temperature" \
  + String(temperature) + " yun";
 
  p.runShellCommand(cmd);
   
  // do nothing until the process finishes, so you get the whole output:
  while (p.running());
 
  char httpStatus[4];
  int i = 0;
  // Read command output. If all went well the 
  // Python script returns the HTTP status 201
  while (p.available()) {
    int serialResult = p.read(); // look for an integer
    if (p.available())
    {
      if (i &lt; 3)
      {
        httpStatus[i] = (char)serialResult;
        i++;
      }
    }
  }
   
  // Compare the return status with the expected HTTP status
  if (strcmp(httpStatus, okHttpStatus) == 0)
  {
    digitalWrite(greenLedPin, HIGH);
    digitalWrite(redLedPin, LOW);
  }
  else
  {
    digitalWrite(greenLedPin, LOW);
    digitalWrite(redLedPin, HIGH);
  }
 
  delay(1000);
}