/* 
** Plot photoresistor(LDR) response curve
** Edward I. Comer December 2012
 */
// Defines
#define DELAYTIME 10000		// Delay 10 seconds
#define	MAXLIGHTLEVEL 25	// Max brightness level
#define STARTLIGHTLEVEL 9      // Starting point
#define	INCREMENT 1		// increment to boost light

// constants won't change. Used here to 
// set pin numbers:
const int localLEDPin =  13;         // the number of the LED pin
const int ldrPin = 1;                // pin number with LDR
const int lightPin = 3;              // pin for flashlight
int LightLevel = STARTLIGHTLEVEL;    // light brightness 0-to-255
int ldrValue = 0;                    // Value read

void setup() {
  // set the digital pin as output:
  pinMode(localLEDPin, OUTPUT); // set pin 13 as output
  Serial.begin(9600); // opens serial port, sets data rate to 9600 bps
//  Serial.println("ldrtest.ino running");
//  Serial.println("waiting 60 seconds");
  analogWrite(lightPin,0);    // settle at starting light level
  delay(10000);		// wait 10 secs for LDR to settle
//  delay(30000);		// wait 30 secs for LDR to settle
  //Serial.println("\"Light value\",\"LDR value\"");
}

void shutdown()
{
    analogWrite(lightPin,0);	// Turn light off
    Serial.print("END");
    Serial.write(0x0a);			// newline character for Linux
    // Rapid blink indicates completion of test
    while(1){  // endless loop
        digitalWrite(localLEDPin, HIGH);   // sets the LED on
	delay(500);                  // waits for a second
	digitalWrite(localLEDPin, LOW);    // sets the LED off
	delay(500);                  // waits for a second
  }
}

void loop()
{
	// Turn on local LED to indicate test start
	digitalWrite(localLEDPin, HIGH);		// local LED on
	analogWrite(lightPin,LightLevel);	// set light brightness
	delay(DELAYTIME);					// wait for LDR to settle
	ldrValue = analogRead(ldrPin);		// read LDR value
	// Turn on local LED to indicate test stopped
	digitalWrite(localLEDPin, LOW);		// local LED off

        Serial.print(LightLevel, DEC);		// Print CSV format X-axis
        //Serial.print(", ");
        Serial.print(" ");
        Serial.print(ldrValue, DEC);		// Print CSV format Y-axis
        Serial.write(0x0a);					// newline character for Linux
    
	LightLevel += INCREMENT;			// increment light brightness
	if(LightLevel > MAXLIGHTLEVEL){
	    shutdown();
	}
    LightLevel &= 255;					// limit variable to 1-byte
}