This is a very simple project that controls a set of LEDs using a DIP switch. The purpose of the sketch is to show the use of some Arduino serial communication functions, and to increase familiarity interfacing with digital I/O pins.

Two LEDs were connected to the RX and TX pins on the Arduino (digital pins 0 and 1), but remember to disconnect these pins while the sketch is being uploaded.

Parts list:

• Arduino Duemilanove
• Breadboard
• 8 LEDs, assorted colors
• Jumper wire, assorted lengths
• DIP switch
• 6 10K Ohm resistors (pull up)
• 8 100 Ohm resistors (current limiting)

Sketch:

// www.TheElectronicsHobbyist.com/blog
// Natalia Fargasch Norman
// LED control via DIP switches

// Arduino pins used for the LEDs
#define LED1 13
#define LED2 12
#define LED3 11
#define LED4 10
#define LED5 9
#define LED6 8

// Arduino pins used for the switches
#define S1 7
#define S2 6
#define S3 5
#define S4 4
#define S5 3
#define S6 2

// State of each switch (0 or 1)
int s1state;
int s2state;
int s3state;
int s4state;
int s5state;
int s6state;

void setup() {
  // pins for LEDs are outputs
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
  pinMode(LED3, OUTPUT);
  pinMode(LED4, OUTPUT);
  pinMode(LED5, OUTPUT);
  pinMode(LED6, OUTPUT);
  // pins for switches are inputs
  pinMode(S1, INPUT);
  pinMode(S2, INPUT);
  pinMode(S3, INPUT);
  pinMode(S4, INPUT);
  pinMode(S5, INPUT);
  pinMode(S6, INPUT);
  // setup serial port
  Serial.begin(9600);
  Serial.println("Serial port open");
}

void loop() {
  s1state = digitalRead(S1);
  digitalWrite(LED1, s1state);
  s2state = digitalRead(S2);
  digitalWrite(LED2, s2state);
  s3state = digitalRead(S3);
  digitalWrite(LED3, s3state);
  s4state = digitalRead(S4);
  digitalWrite(LED4, s4state);
  s5state = digitalRead(S5);
  digitalWrite(LED5, s5state);
  s6state = digitalRead(S6);
  digitalWrite(LED6, s6state);
  Serial.print(s1state);
  Serial.print(s2state);
  Serial.print(s3state);
  Serial.print(s4state);
  Serial.print(s5state);
  Serial.print(s6state);
  Serial.println();
}

A video of the project in action.

You might also enjoy:

1. LED Patterns Using DIP Switch and Arduino
2. Controlling a Seven-Segment Display Using Arduino Part 3
3. Controlling a Seven-Segment Display Using Arduino Part 4
4. Arduino 2-Digit 7-Segment Display with Buttons | Part 4

The third and final Arduino sketch uses bits to represent each segment and is a reduced code version of the previous sketch (1,210 bytes for sketch #3 instead of 1,852 bytes for sketch #2). A ten element array holds a byte for each number 0-9 that specifies what segments should be lit (pin low). Bit 0 corresponds to segment A, bit 1 to segment B and so on. In order to display the number 1, segments B and C need to be lit, so that is represented by the value 0b1111001. Function “lightSegments” reads these bits in sequence and sets the corresponding segments accordingly.

Sketch #3:

// www.TheElectronicsHobbyist.com/blog
// Natalia Fargasch Norman
// Seven-segment LED Display
// Common Anode pins 3 and 8

//   G F + A B
//   | | | | |   -> pins and segments they control
//   ---------
//  F|   A   |B
//   |---G---|   -> segments
//  E|   D   |C
//   ---------
//   | | | | |   -> pins and segments they control
//   E D + C DP

// Segments that make each number when lit:
// 0 => -FEDCBA
// 1 => ----BC-
// 2 => G-ED-BA
// 3 => G--DCBA
// 4 => GF--CB-
// 5 => GF-DC-A
// 6 => GFEDC-A
// 7 => ----CBA
// 8 => GFEDCBA
// 9 => GF-DCBA

// Arduino digital pins used to light up
// corresponding segments on the LED display
#define A 2
#define B 3
#define C 4
#define D 5
#define E 6
#define F 7
#define G 8

// Pushbutton connected to pin 9
#define BUTTON 9

int count = 0; // current display count

const byte numbers[10] = { 0b1000000, 0b1111001, 0b0100100, 0b0110000, 0b0011001, 0b0010010,
0b0000010, 0b1111000, 0b0000000, 0b0010000 };

void setup() {
  pinMode(A, OUTPUT);
  pinMode(B, OUTPUT);
  pinMode(C, OUTPUT);
  pinMode(D, OUTPUT);
  pinMode(E, OUTPUT);
  pinMode(F, OUTPUT);
  pinMode(G, OUTPUT);
  pinMode(BUTTON, INPUT);
  lightSegments(0b1000000);
}

void loop() {
  int val = digitalRead(BUTTON);
  if (val == HIGH) {
    count++;
    if (count == 10) count = 0;
    delay(200);
    lightSegments(numbers[count]);
  }
}

void lightSegments(byte number) {
  for (int i = 0; i < 7; i++) {
    int bit = bitRead(number, i);
    // segments connected to Arduino pins 2-8
    digitalWrite(i+2, bit);
  }
}

Watch a short video of this project in action.

You might also enjoy:

1. Controlling a Seven-Segment Display Using Arduino Part 3
2. Arduino 2-Digit 7-Segment Display with Buttons | Part 4
3. Arduino 2-Digit 7-Segment Display Counter | Part 1
4. Controlling a Seven-Segment Display Using Arduino Part 2

The second sketch cycles through the numbers from 0 to 9, but only increments the display counter each time a button is pressed. Note that this code includes simple debouncing by introducing a short delay when the Arduino detects that the button has been pressed.

Sketch #2:

// www.TheElectronicsHobbyist.com/blog
// Natalia Fargasch Norman
// Seven-segment LED Display
// Common Anode pins 3 and 8

//   G F + A B
//   | | | | |   -> pins and segments they control
//   ---------
//  F|   A   |B
//   |---G---|   -> segments
//  E|   D   |C
//   ---------
//   | | | | |   -> pins and segments they control
//   E D + C DP

// Segments that make each number when lit:
// 0 => ABCDEF
// 1 => BC
// 2 => ABDEG
// 3 => ABCDG
// 4 => BCFG
// 5 => ACDFG
// 6 => ACDEFG
// 7 => ABC
// 8 => ABCDEFG
// 9 => ABCDFG

// Arduino digital pins used to light up
// corresponding segments on the LED display
#define A 2
#define B 3
#define C 4
#define D 5
#define E 6
#define F 7
#define G 8

// Pushbutton connected to pin 9
#define BUTTON 9

// Common anode;
// on when pin is low
// and off when pin is high
#define ON LOW
#define OFF HIGH

int count = 0; // current display count
int val = 0;   // digital input from button

void setup() {
  pinMode(A, OUTPUT);
  pinMode(B, OUTPUT);
  pinMode(C, OUTPUT);
  pinMode(D, OUTPUT);
  pinMode(E, OUTPUT);
  pinMode(F, OUTPUT);
  pinMode(G, OUTPUT);
  pinMode(BUTTON, INPUT);
  zero();
}

void loop() {
  val = digitalRead(BUTTON);
  if (val == HIGH) {
    count++;
    delay(200);
    switch (count) {
      case 0:
        zero();
        break;
      case 1:
        one();
        break;
      case 2:
        two();
        break;
      case 3:
        three();
        break;
      case 4:
        four();
        break;
      case 5:
        five();
        break;
      case 6:
        six();
        break;
      case 7:
        seven();
        break;
      case 8:
        eight();
        break;
      case 9: {
        nine();
        count = -1;
        break;
      }
    }
  }
}

// 0 => ABCDEF
void zero() {
  digitalWrite(A, ON);
  digitalWrite(B, ON);
  digitalWrite(C, ON);
  digitalWrite(D, ON);
  digitalWrite(E, ON);
  digitalWrite(F, ON);
  digitalWrite(G, OFF);
}

// 1 => BC
void one() {
  digitalWrite(A, OFF);
  digitalWrite(B, ON);
  digitalWrite(C, ON);
  digitalWrite(D, OFF);
  digitalWrite(E, OFF);
  digitalWrite(F, OFF);
  digitalWrite(G, OFF);
}

// 2 => ABDEG
void two() {
  digitalWrite(A, ON);
  digitalWrite(B, ON);
  digitalWrite(C, OFF);
  digitalWrite(D, ON);
  digitalWrite(E, ON);
  digitalWrite(F, OFF);
  digitalWrite(G, ON);
}

// 3 => ABCDG
void three() {
  digitalWrite(A, ON);
  digitalWrite(B, ON);
  digitalWrite(C, ON);
  digitalWrite(D, ON);
  digitalWrite(E, OFF);
  digitalWrite(F, OFF);
  digitalWrite(G, ON);
}

// 4 => BCFG
void four() {
  digitalWrite(A, OFF);
  digitalWrite(B, ON);
  digitalWrite(C, ON);
  digitalWrite(D, OFF);
  digitalWrite(E, OFF);
  digitalWrite(F, ON);
  digitalWrite(G, ON);
}

// 5 => ACDFG
void five() {
  digitalWrite(A, ON);
  digitalWrite(B, OFF);
  digitalWrite(C, ON);
  digitalWrite(D, ON);
  digitalWrite(E, OFF);
  digitalWrite(F, ON);
  digitalWrite(G, ON);
}

// 6 => ACDEFG
void six() {
  digitalWrite(A, ON);
  digitalWrite(B, OFF);
  digitalWrite(C, ON);
  digitalWrite(D, ON);
  digitalWrite(E, ON);
  digitalWrite(F, ON);
  digitalWrite(G, ON);
}

// 7 => ABC
void seven() {
  digitalWrite(A, ON);
  digitalWrite(B, ON);
  digitalWrite(C, ON);
  digitalWrite(D, OFF);
  digitalWrite(E, OFF);
  digitalWrite(F, OFF);
  digitalWrite(G, OFF);
}

// 8 => ABCDEFG
void eight() {
  digitalWrite(A, ON);
  digitalWrite(B, ON);
  digitalWrite(C, ON);
  digitalWrite(D, ON);
  digitalWrite(E, ON);
  digitalWrite(F, ON);
  digitalWrite(G, ON);
}

// 9 => ABCDFG
void nine() {
  digitalWrite(A, ON);
  digitalWrite(B, ON);
  digitalWrite(C, ON);
  digitalWrite(D, ON);
  digitalWrite(E, OFF);
  digitalWrite(F, ON);
  digitalWrite(G, ON);
}

You might also enjoy:

1. Controlling a Seven-Segment Display Using Arduino Part 4
2. Controlling a Seven-Segment Display Using Arduino Part 2
3. Arduino 2-Digit 7-Segment Display with Buttons | Part 4
4. Arduino 2-Digit 7-Segment Display Counter | Part 1

This month’s project is a simple program to display the Arabic numbers using the Arduino and a 7-segment display.

Parts list:

• Arduino Duemilanove
• 7-Segment Display(I got the grab bag, with 50 displaysfor $10.95)
• Breadboard
• Mini Push Button Switch
• Jumper Wire

The 7-segment display used in this example is a common anode display with pin connections as shown in the picture, and the Arduino sketches were written so as to light up a segment when the corresponding pin is LOW.

The first of a series of three simple sketches cycles through the numbers from 0 to 9, resets the display to show a “0″ once it reaches “9″ and repeats until the power is turned off on the Arduino. The code below accomplishes this in a very simplified manner, as each digit is formed by a separate function that sequentially lights up each of the necessary segments to display that number.

The third sketch in this sequence will use individual bits to represent each segment and will require less written code, a good thing to keep in mind when programming microcontrollers, as they have a small memory footprint (the Arduino Duemilanove has 32K bytes of program memory).

Sketch #1:

// www.TheElectronicsHobbyist.com/blog
// Natalia Fargasch Norman
// Seven-segment LED Display
// Common Anode pins 3 and 8

//   G F + A B
//   | | | | |   -> pins and segments they control
//   ---------
//  F|   A   |B
//   |---G---|   -> segments
//  E|   D   |C
//   ---------
//   | | | | |   -> pins and segments they control
//   E D + C DP

// Segments that make each number when lit:
// 0 => ABCDEF
// 1 => BC
// 2 => ABDEG
// 3 => ABCDG
// 4 => BCFG
// 5 => ACDFG
// 6 => ACDEFG
// 7 => ABC
// 8 => ABCDEFG
// 9 => ABCDFG

// Arduino digital pins used to light up
// corresponding segments on the LED display
#define A 2
#define B 3
#define C 4
#define D 5
#define E 6
#define F 7
#define G 8

// Common anode;
// on when pin is low
// and off when pin is high
#define ON LOW
#define OFF HIGH

int ms = 1000;

void setup() {
  pinMode(A, OUTPUT);
  pinMode(B, OUTPUT);
  pinMode(C, OUTPUT);
  pinMode(D, OUTPUT);
  pinMode(E, OUTPUT);
  pinMode(F, OUTPUT);
  pinMode(G, OUTPUT);
}

void loop() {
  zero();
  one();
  two();
  three();
  four();
  five();
  six();
  seven();
  eight();
  nine();
}

// 0 => ABCDEF
void zero() {
  digitalWrite(A, ON);
  digitalWrite(B, ON);
  digitalWrite(C, ON);
  digitalWrite(D, ON);
  digitalWrite(E, ON);
  digitalWrite(F, ON);
  digitalWrite(G, OFF);
  delay(ms);
}

// 1 => BC
void one() {
  digitalWrite(A, OFF);
  digitalWrite(B, ON);
  digitalWrite(C, ON);
  digitalWrite(D, OFF);
  digitalWrite(E, OFF);
  digitalWrite(F, OFF);
  digitalWrite(G, OFF);
  delay(ms);
}

// 2 => ABDEG
void two() {
  digitalWrite(A, ON);
  digitalWrite(B, ON);
  digitalWrite(C, OFF);
  digitalWrite(D, ON);
  digitalWrite(E, ON);
  digitalWrite(F, OFF);
  digitalWrite(G, ON);
  delay(ms);
}

// 3 => ABCDG
void three() {
  digitalWrite(A, ON);
  digitalWrite(B, ON);
  digitalWrite(C, ON);
  digitalWrite(D, ON);
  digitalWrite(E, OFF);
  digitalWrite(F, OFF);
  digitalWrite(G, ON);
  delay(ms);
}

// 4 => BCFG
void four() {
  digitalWrite(A, OFF);
  digitalWrite(B, ON);
  digitalWrite(C, ON);
  digitalWrite(D, OFF);
  digitalWrite(E, OFF);
  digitalWrite(F, ON);
  digitalWrite(G, ON);
  delay(ms);
}

// 5 => ACDFG
void five() {
  digitalWrite(A, ON);
  digitalWrite(B, OFF);
  digitalWrite(C, ON);
  digitalWrite(D, ON);
  digitalWrite(E, OFF);
  digitalWrite(F, ON);
  digitalWrite(G, ON);
  delay(ms);
}

// 6 => ACDEFG
void six() {
  digitalWrite(A, ON);
  digitalWrite(B, OFF);
  digitalWrite(C, ON);
  digitalWrite(D, ON);
  digitalWrite(E, ON);
  digitalWrite(F, ON);
  digitalWrite(G, ON);
  delay(ms);
}

// 7 => ABC
void seven() {
  digitalWrite(A, ON);
  digitalWrite(B, ON);
  digitalWrite(C, ON);
  digitalWrite(D, OFF);
  digitalWrite(E, OFF);
  digitalWrite(F, OFF);
  digitalWrite(G, OFF);
  delay(ms);
}

// 8 => ABCDEFG
void eight() {
  digitalWrite(A, ON);
  digitalWrite(B, ON);
  digitalWrite(C, ON);
  digitalWrite(D, ON);
  digitalWrite(E, ON);
  digitalWrite(F, ON);
  digitalWrite(G, ON);
  delay(ms);
}

// 9 => ABCDFG
void nine() {
  digitalWrite(A, ON);
  digitalWrite(B, ON);
  digitalWrite(C, ON);
  digitalWrite(D, ON);
  digitalWrite(E, OFF);
  digitalWrite(F, ON);
  digitalWrite(G, ON);
  delay(ms);
}

You might also enjoy:

1. Controlling a Seven-Segment Display Using Arduino Part 3
2. Controlling a Seven-Segment Display Using Arduino Part 4
3. Arduino 2-Digit 7-Segment Display with Buttons | Part 4
4. Arduino 2-Digit 7-Segment Display Counter | Part 1