adc.ino

/*HCHOtest1.0.ino 
Barebones sketch to read an analog voltage between 0 and 100mV.
An internal reference voltage of 1.1v is used to scale the digital conversion.
The maximum output of the HCHO sensor (100mV) is converted to a value of 103.
This value of 103 should equal a reading of 1000ppb HCHO.
*/

int analogPin = 3;          // Tip of output HCHO sensor jack connected to analog pin 3
                            // Ring of HCHO sensor connector connected to GND
int voltRaw = 0;            // variable to store the sensor value read
int ppbHCHO = 0;            // variable to store a result

void setup()
{
  analogReference(INTERNAL);       // Set analog reference to 1.1 volts
  Serial.begin(9600);              //  setup serial
}

void loop()
{
  voltRaw = analogRead(analogPin);                       // read the input pin
  ppbHCHO = voltRaw*10;                                  // scale the result between 0 and 1023
  
  Serial.print("Value between 0 and 103: ");             // Print to serial monitor
  Serial.println(voltRaw);                               // this is the conversion of the analog voltage to a digital number
  Serial.print("Value between 0 and 1023");               
  Serial.println(ppbHCHO);                               // This might approximate ppb

  delay(3000);                                           // take a reading and print to the serial monitor every 3 seconds
}