Upload the Logic Tester Sketch

With the Logic Tester built, it’s time to upload the sketch. As shown in Example 15-1, the sketch operates an RGB LED using a pushbutton switch and two fixed resistors. Here are the steps you’ll need to follow:

1. Attach the Arduino to your computer using a USB cable.
2. Open the Arduino software and type Example 15-1 into the software’s text editor.
3. Upload the sketch to the Arduino.

Once the Logic Tester sketch has been uploaded to the Arduino microcontroller, the RGB’s red LED will be on, as shown in Figure 15-1. Attaching the long test wire to the +5VDC source on the MakerShield and pressing the pushbutton switch will allow the RGB green LED to turn on, as shown in Figure 15-3.

Example 15-1. The Logic Tester sketch

/*
  Logic Tester with RGB LED

  Turns on the green LED when a logic "1" (+5V) signal is detected. The
  red LED will turn on at logic "0" (0V) signal.  Also, when powering
  up the Arduino the red LED is on.

  4 May 2013
  Don Wilcher

 */

// RG pins wired to the Arduino microcontroller
// give them names:
int redled = 9;
int grnled = 10;
int probein = 8;
int probeStatus = 0;

// the setup routine runs once when you press reset:
void setup() {
 // initialize the digital pins as outputs:
  pinMode(redled, OUTPUT);
  pinMode(grnled, OUTPUT);
  pinMode(probein, INPUT);
  // turn RGB outputs off:
  digitalWrite(redled, HIGH);
  digitalWrite(grnled, HIGH);

}

// the loop routine runs over and over again forever:
void loop() {
// read the status of the test probe value:
probeStatus = digitalRead(probein);

if (probeStatus == HIGH) { // check if the test probe value is HIGH

  digitalWrite(redled, HIGH);       // turn the red LED off (HIGH is off)
  digitalWrite(grnled, LOW);        // turn the green LED on (LOW is on)
 }
else {

   digitalWrite(redled, LOW);       // turn the red LED on
   digitalWrite(grnled, HIGH);      // turn the green LED off

   }
}

TECH NOTE

HIGH is equivalent to binary 1 and LOW is equivalent to binary 0.

Figure 15-3. The Logic Tester checking +5VDC on MakerShield