Tuesday, May 21, 2013


This last weekend I went to the Maker's Fair and got a free breadboard Arduino. What a swag score After making a blinky light I decided to order a few parts from SparkFun Electronics and decided to toy around with a 7-segment display (I now wished I had gotten something a bit more challenging, but hey, I haven't done electronics in a long time). I followed the tutorial here and noticed many Arduino examples don't use objects. So, here is a version of the SparkFun 7-segment display example using objects.

/* Serial 7-Segment Display Example Code
    Serial Mode Stopwatch
   by: Jim Lindblom
     SparkFun Electronics
   date: November 27, 2012
   license: This code is public domain.
   This example code shows how you could use software serial
   Arduino library to interface with a Serial 7-Segment Display.
   There are example functions for setting the display's
   brightness, decimals and clearing the display.
   The print function is used with the SoftwareSerial library
   to send display data to the S7S.
   Arduino -------------- Serial 7-Segment
     5V   --------------------  VCC
     GND  --------------------  GND
      8   --------------------  RX

class LED
    // These are the Arduino pins required to create a software seiral
    //  instance. We'll actually only use the TX pin.
    int softwareTx;
    int softwareRx;
    SoftwareSerial *s7s;
      s7s = NULL;
    void initialize()
        softwareTx = 8;
        softwareRx = 7;
        s7s = new SoftwareSerial(softwareRx, softwareTx);
        // Must begin s7s software serial at the correct baud rate.
        //  The default of the s7s is 9600.
        // Clear the display, and then turn on all segments and decimals
        clearDisplay();  // Clears display, resets cursor
        s7s->print("-HI-");  // Displays -HI- on all digits
        setDecimals(0b111111);  // Turn on all decimals, colon, apos
        // Flash brightness values at the beginning
        setBrightness(0);  // Lowest brightness
        setBrightness(127);  // Medium brightness
        setBrightness(255);  // High brightness
        // Clear the display before jumping into loop
      if (s7s != NULL)
        delete s7s;
    void printDisplay(int value)
        char tempString[10];  // Will be used with sprintf to create strings
        // Magical sprintf creates a string for us to send to the s7s.
        //  The %4d option creates a 4-digit integer.
        sprintf(tempString, "%4d", value);
        // This will output the tempString to the S7S
    // Send the clear display command (0x76)
    //  This will clear the display and reset the cursor
    void clearDisplay()
      s7s->write(0x76);  // Clear display command
    // Set the displays brightness. Should receive byte with the value
    //  to set the brightness to
    //  dimmest------------->brightest
    //     0--------127--------255
    void setBrightness(byte value)
      s7s->write(0x7A);  // Set brightness command byte
      s7s->write(value);  // brightness data byte
    // Turn on any, none, or all of the decimals.
    //  The six lowest bits in the decimals parameter sets a decimal 
    //  (or colon, or apostrophe) on or off. A 1 indicates on, 0 off.
    //  [MSB] (X)(X)(Apos)(Colon)(Digit 4)(Digit 3)(Digit2)(Digit1)
    // Example: setDecimals(0b00000100);  // Sets digit 3 decimal on
    void setDecimals(byte decimals)

unsigned int counter = 0;  // This variable will count up to 65k
LED Led;

void setup()

void loop()
  Led.setDecimals(0b00000100);  // Sets digit 3 decimal on
  counter++;  // Increment the counter
  delay(100);  // This will make the display update at 10Hz.