New Pololu QTRX Sensors

Other Hardware Sensors
1

Hello Group!

I recently purchased some new QTRX-RC sensors from Pololu and I used their Arduino library to use the sensors and their examples work fine. Now I have a question. I am trying to turn on an LED and then turn it back off. I am having some difficulty in doing so. The code is below. I tried reading the values and creating a threshhold however that failed to work.

#include <QTRSensors.h>

#define NUM_SENSORS   2                               
#define TIMEOUT       2500                              
#define EMITTER_PIN    QTR_NO_EMITTER_PIN   

QTRSensorsRC qtrrc((unsigned char[]) {3, 4},
  NUM_SENSORS, TIMEOUT, EMITTER_PIN);
unsigned int sensorValues[NUM_SENSORS];


void setup() {
delay(500);
pinMode(13, OUTPUT);
digitalWrite(13, HIGH);    
for (int i = 0; i < 400; i++) {
qtrrc.calibrate();  
}
digitalWrite(13, LOW); 

Serial.begin(9600);
for (int i = 0; i < NUM_SENSORS; i++) {
Serial.print(qtrrc.calibratedMinimumOn[i]);
Serial.print(' ');
}
Serial.println();

for (int i = 0; i < NUM_SENSORS; i++) {
Serial.print(qtrrc.calibratedMaximumOn[i]);
Serial.print(' ');
}
Serial.println();
Serial.println();
delay(1000);
}


void loop() {
qtrrc.read(sensorValues);
for (unsigned char i = 0; i < NUM_SENSORS; i++) {
Serial.print(sensorValues[i]);
Serial.print('\t');
}
Serial.println();
delay(250);
}

How would I write the code to turn an LED on or OFF? This code is from their own Arduino Library. Thanks for the help!

2

I was able to get the code to turn and LED on and OFF by using a threshold below:

void loop(){

qtrrc.read(sensorValues); 

for (unsigned char i = 0; i < NUM_SENSORS; i++){
Serial.print(sensorValues[i]);
Serial.print('\t');
Serial.print('\t');
}
Serial.println();
delay(250);
if(sensorValues[0] && sensorValues[1] < 600) {
digitalWrite(13, HIGH);
} else {
digitalWrite(13, LOW);
}
}

However I would like to not use the threshold values as the sensor could be in any room with different lighting. How can I take the sensor readings and just use a simple HIGH and LOW and would it react the same as if I was using the threshold numbers? Thanks!