gistfile1.txt

/*
  Analog Input
 Demonstrates analog input by reading an analog sensor on analog pin 0 and
 turning on and off a light emitting diode(LED)  connected to digital pin 13.
 The amount of time the LED will be on and off depends on
 the value obtained by analogRead().

 The circuit:
 * Potentiometer attached to analog input 0
 * center pin of the potentiometer to the analog pin
 * one side pin (either one) to ground
 * the other side pin to +5V
 * LED anode (long leg) attached to digital output 13
 * LED cathode (short leg) attached to ground

 * Note: because most Arduinos have a built-in LED attached
 to pin 13 on the board, the LED is optional.


 Created by David Cuartielles
 modified 30 Aug 2011
 By Tom Igoe

 This example code is in the public domain.

 http://www.arduino.cc/en/Tutorial/AnalogInput

 */

int sensorPin = A0;    // select the input pin for the potentiometer
int ledPin = 13;      // select the pin for the LED
int16_t sensorValue = 0;  // variable to store the value coming from the sensor
int count = 0;

const int Setter = 5;
const int Unsetter = 6;

// the setup function runs once when you press reset or power the board
void setup() {
  pinMode(Setter, OUTPUT);
  pinMode(Unsetter, OUTPUT);

  // declare the ledPin as an OUTPUT:
  pinMode(ledPin, OUTPUT);
  Serial.println("Well, setup completed...");
}

void loop() {
  Serial.print("About to read_differential... ");
  Serial.println(count);
  // analogReference(EXTERNAL);
  sensorValue = analogRead(A0); // adc_read(0x30); //
  Serial.print("A0=");
  Serial.println(sensorValue);
  sensorValue = analogRead(A4); // adc_read(0x30); //
  Serial.print("A4=");
  Serial.println(sensorValue);
  if (sensorValue > 0) {
    digitalWrite(ledPin, HIGH);
    pulse(Setter);
  } else {
    digitalWrite(ledPin, LOW);
    pulse(Unsetter);
  }
  delay(500);
  count++;
}


void pulse(int pin) {
  digitalWrite(pin, HIGH);
  delay(15);
  digitalWrite(pin, LOW);
}

int16_t adc_read(byte mux)
{
    // _BV(REFS1) | _BV(REFS0) |
    ADMUX = _BV(REFS1) | _BV(REFS0) | (mux & 0x1f);
    ADCSRB = _BV(ADHSM); // high speed mode
    if(mux & 0x20) ADCSRB |= _BV(MUX5);
    delayMicroseconds(125); // required for amplifier to settle
    
    // Start the conversion
    bitWrite(ADCSRA, ADSC, 1);
    delayMicroseconds(125); // required for amplifier to settle
    
    while (bit_is_set(ADCSRA, ADSC));

    uint8_t low  = ADCL; // must read ADCL first - it then locks ADCH
    uint8_t high = ADCH; // unlocks both
    
    Serial.print("Read values...\nlow=");
    Serial.print(low);
    Serial.print(" high=");
    Serial.println(high);

    int smallInt = (uint16_t)high << 8 | (uint16_t)low;
const int negative = (smallInt & (1 << 9)) != 0;
int nativeInt;

if (negative)
  nativeInt = smallInt | ~((1 << 10) - 1);
else
  nativeInt = smallInt;
    
    return nativeInt;
}