Arduino - RowColumnScanning

May 02, 2012, at 10:04 AM by Scott Fitzgerald -

Changed line 191 from:

(:source http://github.com/arduino/Arduino/raw/master/build/shared/examples/7.Display/RowColumnScanning/RowColumnScanning.ino lang=arduino tabwidth=4:)

to:

(:source http://github.com/arduino/Arduino/raw/master/build/shared/examples/07.Display/RowColumnScanning/RowColumnScanning.ino lang=arduino tabwidth=4:)

November 15, 2011, at 10:20 PM by Scott Fitzgerald -

Changed line 191 from:

(:source http://github.com/arduino/Arduino/raw/master/build/shared/examples/7.Display/RowColumnScanning/RowColumnScanning.pde lang=arduino tabwidth=4:)

to:

(:source http://github.com/arduino/Arduino/raw/master/build/shared/examples/7.Display/RowColumnScanning/RowColumnScanning.ino lang=arduino tabwidth=4:)

September 23, 2010, at 11:54 PM by Tom Igoe -

Changed lines 207-208 from:

LED Bar Graph ?: how to make an LED bar graph.

to:

LED Bar Graph: how to make an LED bar graph.

September 23, 2010, at 04:43 PM by Christian Cerrito -

Changed lines 3-4 from:

Row-columm Scanning to control an 8x8 LED Matrix

to:

Row-columm Scanning to control an 8x8 LED Matrix

September 19, 2010, at 04:01 PM by Christian Cerrito -

Added line 210:

September 19, 2010, at 03:56 PM by Christian Cerrito -

Changed lines 207-208 from:

Row Column Scanning - how to control an 8x8 matrix of LEDs.

to:

LED Bar Graph ?: how to make an LED bar graph.

September 19, 2010, at 03:53 PM by Christian Cerrito -

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Writing Functions ? - create modular pieces of code to perform a defined task.

to:

Writing Functions - create modular pieces of code to perform a defined task.

Added lines 213-215:

September 19, 2010, at 03:52 PM by Christian Cerrito -

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to:

Hardware Required

Arduino Board
(1) 8 x 8 LED Matrix
(2) potentiometers
hook-up wire
breadboard

September 16, 2010, at 04:20 PM by Tom Igoe -

Changed line 183 from:

 (:source http://github.com/arduino/Arduino/raw/master/build/shared/examples/Display/RowColumnScanning/RowColumnScanning.pde lang=arduino  tabwidth=4:)

to:

(:source http://github.com/arduino/Arduino/raw/master/build/shared/examples/7.Display/RowColumnScanning/RowColumnScanning.pde lang=arduino tabwidth=4:)

February 23, 2010, at 10:33 PM by Tom Igoe -

Changed lines 183-214 from:

 /*
   Row-Column Scanning an 8x8 LED matrix with X-Y input
  
  This example controls an 8x8 LED matrix using two analog inputs
  
  created 27 May 2009
  modified 29 Jun 2009
  by Tom Igoe
  
  This example works for the Lumex  LDM-24488NI Matrix. See 
  http://sigma.octopart.com/140413/datasheet/Lumex-LDM-24488NI.pdf
  for the pin connections
  
  For other LED cathode column matrixes, you should only need to change 
  the pin numbers in the row[] and column[] arrays
  
  rows are the anodes
  cols are the cathodes
  ---------
  
  Pin numbers:
  Matrix:
  * Digital pins 2 through 13,
  * analog pins 2 through 5 used as digital 16 through 19
  Potentiometers:
  * center pins are attached to analog pins 0 and 1, respectively
  * side pins attached to +5V and ground, respectively.
  
  http://www.arduino.cc/en/Tutorial/RowColumnScanning
  
  see also http://www.tigoe.net/pcomp/code/category/arduinowiring/514 for more
  */

to:

 (:source http://github.com/arduino/Arduino/raw/master/build/shared/examples/Display/RowColumnScanning/RowColumnScanning.pde lang=arduino  tabwidth=4:)

Deleted lines 184-263:

 // 2-dimensional array of row pin numbers:
 const int row[8] = {
   2,7,19,5,13,18,12,16 };

 // 2-dimensional array of column pin numbers:
 const int col[8] = {
   6,11,10,3,17,4,8,9  };

 // 2-dimensional array of pixels:
 int pixels[8][8];

 // cursor position:
 int x = 5;
 int y = 5;

 void setup() {
   Serial.begin(9600);
   // initialize the I/O pins as outputs:

   // iterate over the pins:
   for (int thisPin = 0; thisPin < 8; thisPin++) {
     // initialize the output pins:
     pinMode(col[thisPin], OUTPUT); 
     pinMode(row[thisPin], OUTPUT);  
     // take the col pins (i.e. the cathodes) high to ensure that
     // the LEDS are off: 
     digitalWrite(col[thisPin], HIGH);    
   }

   // initialize the pixel matrix:
   for (int x = 0; x < 8; x++) {
     for (int y = 0; y < 8; y++) {
       pixels[x][y] = HIGH;
     }
   }
 }

 void loop() {
   // read input:
   readSensors();

   // draw the screen:
   refreshScreen();
 }

 void readSensors() {
   // turn off the last position:
   pixels[x][y] = HIGH;
   // read the sensors for X and Y values:
   x = 7 - map(analogRead(0), 0, 1023, 0, 7);
   y = map(analogRead(1), 0, 1023, 0, 7);
   // set the new pixel position low so that the LED will turn on
   // in the next screen refresh:
   pixels[x][y] = LOW;

 void refreshScreen() {
   // iterate over the rows (anodes):
   for (int thisRow = 0; thisRow < 8; thisRow++) {
     // take the row pin (anode) high:
     digitalWrite(row[thisRow], HIGH);
     // iterate over the cols (cathodes):
     for (int thisCol = 0; thisCol < 8; thisCol++) {
       // get the state of the current pixel;
       int thisPixel = pixels[thisRow][thisCol];
       // when the row is HIGH and the col is LOW,
       // the LED where they meet turns on:
       digitalWrite(col[thisCol], thisPixel);
       // turn the pixel off:
       if (thisPixel == LOW) {
         digitalWrite(col[thisCol], HIGH);
       }
     }
     // take the row pin low to turn off the whole row:
     digitalWrite(row[thisRow], LOW);
   }
 }

November 26, 2009, at 12:17 AM by David A. Mellis -

Changed line 219 from:

   2,7,19,5,18,12,16 };

to:

   2,7,19,5,13,18,12,16 };

August 27, 2009, at 02:57 PM by Tom Igoe -

Added lines 170-172:

image developed using Fritzing. For more circuit examples, see the Fritzing project page

July 05, 2009, at 01:50 PM by Tom Igoe -

Changed lines 177-179 from:

[@ /*

  Row-Column Scanning an 8x8 LED matrix with X-Y input

to:

(:div class=code :)

 /*
   Row-Column Scanning an 8x8 LED matrix with X-Y input
  
  This example controls an 8x8 LED matrix using two analog inputs
  
  created 27 May 2009
  modified 29 Jun 2009
  by Tom Igoe
  
  This example works for the Lumex  LDM-24488NI Matrix. See 
  http://sigma.octopart.com/140413/datasheet/Lumex-LDM-24488NI.pdf
  for the pin connections
  
  For other LED cathode column matrixes, you should only need to change 
  the pin numbers in the row[] and column[] arrays
  
  rows are the anodes
  cols are the cathodes
  ---------
  
  Pin numbers:
  Matrix:
  * Digital pins 2 through 13,
  * analog pins 2 through 5 used as digital 16 through 19
  Potentiometers:
  * center pins are attached to analog pins 0 and 1, respectively
  * side pins attached to +5V and ground, respectively.
  
  http://www.arduino.cc/en/Tutorial/RowColumnScanning
  
  see also http://www.tigoe.net/pcomp/code/category/arduinowiring/514 for more
  */

Deleted line 212:

 This example controls an 8x8 LED matrix using two analog inputs

Changed lines 214-216 from:

 created 27 May 2009
 modified 29 Jun 2009
 by Tom Igoe

to:

 // 2-dimensional array of row pin numbers:
 const int row[8] = {
   2,7,19,5,18,12,16 };

Changed lines 218-220 from:

 This example works for the Lumex  LDM-24488NI Matrix. See 
 http://sigma.octopart.com/140413/datasheet/Lumex-LDM-24488NI.pdf
 for the pin connections

to:

 // 2-dimensional array of column pin numbers:
 const int col[8] = {
   6,11,10,3,17,4,8,9  };

Changed lines 222-223 from:

 For other LED cathode column matrixes, you should only need to change 
 the pin numbers in the row[] and column[] arrays

to:

 // 2-dimensional array of pixels:
 int pixels[8][8];

Changed lines 225-227 from:

 rows are the anodes
 cols are the cathodes
 ---------

to:

 // cursor position:
 int x = 5;
 int y = 5;

Changed lines 229-235 from:

 Pin numbers:
 Matrix:
 * Digital pins 2 through 13,
 * analog pins 2 through 5 used as digital 16 through 19
 Potentiometers:
 * center pins are attached to analog pins 0 and 1, respectively
 * side pins attached to +5V and ground, respectively.

to:

 void setup() {
   Serial.begin(9600);
   // initialize the I/O pins as outputs:

Changed lines 233-241 from:

 http://www.arduino.cc/en/Tutorial/RowColumnScanning

to:

   // iterate over the pins:
   for (int thisPin = 0; thisPin < 8; thisPin++) {
     // initialize the output pins:
     pinMode(col[thisPin], OUTPUT); 
     pinMode(row[thisPin], OUTPUT);  
     // take the col pins (i.e. the cathodes) high to ensure that
     // the LEDS are off: 
     digitalWrite(col[thisPin], HIGH);    
   }

Changed lines 243-325 from:

 see also http://www.tigoe.net/pcomp/code/category/arduinowiring/514 for more
 */

// 2-dimensional array of row pin numbers: const int row[8] = {

  2,7,19,5,18,12,16 };

// 2-dimensional array of column pin numbers: const int col[8] = {

  6,11,10,3,17,4,8,9  };

// 2-dimensional array of pixels: int pixels[8][8];

// cursor position: int x = 5; int y = 5;

void setup() {

  Serial.begin(9600);
  // initialize the I/O pins as outputs:

  // iterate over the pins:
  for (int thisPin = 0; thisPin < 8; thisPin++) {
    // initialize the output pins:
    pinMode(col[thisPin], OUTPUT); 
    pinMode(row[thisPin], OUTPUT);  
    // take the col pins (i.e. the cathodes) high to ensure that
    // the LEDS are off: 
    digitalWrite(col[thisPin], HIGH);    
  }

  // initialize the pixel matrix:
  for (int x = 0; x < 8; x++) {
    for (int y = 0; y < 8; y++) {
      pixels[x][y] = HIGH;
    }
  }

}

void loop() {

  // read input:
  readSensors();

  // draw the screen:
  refreshScreen();

}

void readSensors() {

  // turn off the last position:
  pixels[x][y] = HIGH;
  // read the sensors for X and Y values:
  x = 7 - map(analogRead(0), 0, 1023, 0, 7);
  y = map(analogRead(1), 0, 1023, 0, 7);
  // set the new pixel position low so that the LED will turn on
  // in the next screen refresh:
  pixels[x][y] = LOW;

}

void refreshScreen() {

  // iterate over the rows (anodes):
  for (int thisRow = 0; thisRow < 8; thisRow++) {
    // take the row pin (anode) high:
    digitalWrite(row[thisRow], HIGH);
    // iterate over the cols (cathodes):
    for (int thisCol = 0; thisCol < 8; thisCol++) {
      // get the state of the current pixel;
      int thisPixel = pixels[thisRow][thisCol];
      // when the row is HIGH and the col is LOW,
      // the LED where they meet turns on:
      digitalWrite(col[thisCol], thisPixel);
      // turn the pixel off:
      if (thisPixel == LOW) {
        digitalWrite(col[thisCol], HIGH);
      }
    }
    // take the row pin low to turn off the whole row:
    digitalWrite(row[thisRow], LOW);
  }

} @]

to:

   // initialize the pixel matrix:
   for (int x = 0; x < 8; x++) {
     for (int y = 0; y < 8; y++) {
       pixels[x][y] = HIGH;
     }
   }
 }

 void loop() {
   // read input:
   readSensors();

   // draw the screen:
   refreshScreen();
 }

 void readSensors() {
   // turn off the last position:
   pixels[x][y] = HIGH;
   // read the sensors for X and Y values:
   x = 7 - map(analogRead(0), 0, 1023, 0, 7);
   y = map(analogRead(1), 0, 1023, 0, 7);
   // set the new pixel position low so that the LED will turn on
   // in the next screen refresh:
   pixels[x][y] = LOW;

 void refreshScreen() {
   // iterate over the rows (anodes):
   for (int thisRow = 0; thisRow < 8; thisRow++) {
     // take the row pin (anode) high:
     digitalWrite(row[thisRow], HIGH);
     // iterate over the cols (cathodes):
     for (int thisCol = 0; thisCol < 8; thisCol++) {
       // get the state of the current pixel;
       int thisPixel = pixels[thisRow][thisCol];
       // when the row is HIGH and the col is LOW,
       // the LED where they meet turns on:
       digitalWrite(col[thisCol], thisPixel);
       // turn the pixel off:
       if (thisPixel == LOW) {
         digitalWrite(col[thisCol], HIGH);
       }
     }
     // take the row pin low to turn off the whole row:
     digitalWrite(row[thisRow], LOW);
   }
 }

(:divend:)

June 30, 2009, at 11:13 AM by Tom Igoe -

Changed line 184 from:

 modified 26 Jun 2009

to:

 modified 29 Jun 2009

Changed lines 189-196 from:

 for the pin connections.

  For other LED cathode column matrixes, you should only need to change 
  the pin numbers in the row[] and column[] arrays

 rows are the anodes
 cols are the cathodes
 ---------

to:

 for the pin connections

Added lines 191-197:

 For other LED cathode column matrixes, you should only need to change 
 the pin numbers in the row[] and column[] arrays

 rows are the anodes
 cols are the cathodes
 ---------

Changed lines 202-203 from:

 Accelerometer: 
 * X and Y axes attached to analog in 0 and 1

to:

 Potentiometers:
 * center pins are attached to analog pins 0 and 1, respectively
 * side pins attached to +5V and ground, respectively.

Changed lines 206-208 from:

  http://www.arduino.cc/en/Tutorial/RowColumnScanning

 see http://www.tigoe.net/pcomp/code/category/arduinowiring/514 for more

to:

 http://www.arduino.cc/en/Tutorial/RowColumnScanning

 see also http://www.tigoe.net/pcomp/code/category/arduinowiring/514 for more

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// max and min values from the accelerometer, // found by experiment: const int sensorMin = 380; const int sensorMax = 620;

to:

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   2,7,19,5,18,12,16 };

to:

  2,7,19,5,18,12,16 };

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  x = 7 - map(analogRead(0), sensorMin, sensorMax, 0, 7);
  y = map(analogRead(1), sensorMin, sensorMax, 0, 7);

to:

  x = 7 - map(analogRead(0), 0, 1023, 0, 7);
  y = map(analogRead(1), 0, 1023, 0, 7);
  // set the new pixel position low so that the LED will turn on
  // in the next screen refresh:

June 30, 2009, at 11:11 AM by Tom Igoe -

Changed lines 172-173 from:

click the image to enlarge

to:

click the image to enlarge.

June 29, 2009, at 12:00 PM by Tom Igoe -

Added lines 162-165:

the 16 pins of the matrix are hooked up to 16 pins of the Arduino. Four of the analog pins are used as digital inputs 16 through 19. The order of the pins is assigned in two arrays in the code.

Two potentiometers control the movement of a lit LED in the matrix.

June 29, 2009, at 11:53 AM by Tom Igoe -

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Although there are pre-made LED matrices, you can also make your own matrix from 64 LEDs, using the schematic as shown above.

Deleted lines 21-22:

June 29, 2009, at 11:51 AM by Tom Igoe -

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LED displays are often packaged as matrixes of LEDs arranged in rows of common anodes and columns of common cathodes, or the reverse. Here's a typical example, and its schematic:

to:

LED displays are often packaged as matrixes of LEDs arranged in rows of common anodes and columns of common cathodes, or the reverse. Here's a typical example, and its schematic:

June 29, 2009, at 11:51 AM by Tom Igoe -

Changed lines 175-176 from:

  Row-Column Scanning an 8x8 LED matrix with accelerometer
 for Arduino

to:

  Row-Column Scanning an 8x8 LED matrix with X-Y input

Changed lines 177-178 from:

 This example controls an 8x8 LED matrix using two inputs
 from an accelerometer.

to:

 This example controls an 8x8 LED matrix using two analog inputs

Changed lines 183-186 from:

 This example works for the Fairchild GMA2288C matrix.  See

http://sigma.octopart.com/125394/datasheet/Fairchild-GMA2288C.pdf for the pin connections

to:

 This example works for the Lumex  LDM-24488NI Matrix. See 
 http://sigma.octopart.com/140413/datasheet/Lumex-LDM-24488NI.pdf
 for the pin connections.

  For other LED cathode column matrixes, you should only need to change 
  the pin numbers in the row[] and column[] arrays

Added line 203:

 see http://www.tigoe.net/pcomp/code/category/arduinowiring/514 for more

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   9,8,7,6,16,17,18,19 };

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   2,7,19,5,18,12,16 };

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  13,12,11,10,5,4,3,2  };

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  6,11,10,3,17,4,8,9  };

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June 29, 2009, at 11:47 AM by Tom Igoe -

June 29, 2009, at 11:44 AM by Tom Igoe -

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June 29, 2009, at 11:43 AM by Tom Igoe -

June 29, 2009, at 11:42 AM by Tom Igoe -

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Examples > Display

Row-columm Scanning to control an 8x8 LED Matrix

LED displays are often packaged as matrixes of LEDs arranged in rows of common anodes and columns of common cathodes, or the reverse. Here's a typical example, and its schematic:

These can be very useful displays. To control a matrix, you connect both its rows and columns to your microcontroller. The columns are connected to the LEDs anodes (see Figure 1), so a column needs to be high for any of the LEDs in that column to turn on. The rows are connected to the LEDs cathodes, so the row needs to be low for an individual LED to turn on. If the row and the column are both high or both low, no voltage flows through the LED and it doesn’t turn on.

To control an individual LED, you set its column high and its row low. To control multiple LEDs in a row, you set the rows high, then take the column high, then set the lows row or high as appropriate; a low row will turn the corresponding LED on, and a high row will turn it off.

It doesn’t matter which pins of the microcontroller you connect the rows and columns to, because you can assign things in software. Connected the pins in a way that makes wiring easiest. A typical layout is shown below.

Circuit

click the image to enlarge

Schematic:

click the image to enlarge

Code

/*
  Row-Column Scanning an 8x8 LED matrix with accelerometer
 for Arduino 

 This example controls an 8x8 LED matrix using two inputs
 from an accelerometer.

 created 27 May 2009
 modified 26 Jun 2009
 by Tom Igoe

 This example works for the Fairchild GMA2288C matrix.  See
http://sigma.octopart.com/125394/datasheet/Fairchild-GMA2288C.pdf
for the pin connections

 rows are the anodes
 cols are the cathodes
 ---------

 Pin numbers:
 Matrix:
 * Digital pins 2 through 13,
 * analog pins 2 through 5 used as digital 16 through 19
 Accelerometer: 
 * X and Y axes attached to analog in 0 and 1

  http://www.arduino.cc/en/Tutorial/RowColumnScanning

 */

// max and min values from the accelerometer, 
// found by experiment:
const int sensorMin = 380;
const int sensorMax = 620;

// 2-dimensional array of row pin numbers:
const int row[8] = {
   9,8,7,6,16,17,18,19 };

// 2-dimensional array of column pin numbers:
const int col[8] = {
  13,12,11,10,5,4,3,2  };

// 2-dimensional array of pixels:
int pixels[8][8];           

// cursor position:
int x = 5;
int y = 5;

void setup() {
  Serial.begin(9600);
  // initialize the I/O pins as outputs:

  // iterate over the pins:
  for (int thisPin = 0; thisPin < 8; thisPin++) {
    // initialize the output pins:
    pinMode(col[thisPin], OUTPUT); 
    pinMode(row[thisPin], OUTPUT);  
    // take the col pins (i.e. the cathodes) high to ensure that
    // the LEDS are off: 
    digitalWrite(col[thisPin], HIGH);    
  }

  // initialize the pixel matrix:
  for (int x = 0; x < 8; x++) {
    for (int y = 0; y < 8; y++) {
      pixels[x][y] = HIGH;
    }
  }
}

void loop() {
  // read input:
  readSensors();

  // draw the screen:
  refreshScreen();

}

void readSensors() {
  // turn off the last position:
  pixels[x][y] = HIGH;
  // read the sensors for X and Y values:
  x = 7 - map(analogRead(0), sensorMin, sensorMax, 0, 7);
  y = map(analogRead(1), sensorMin, sensorMax, 0, 7);
  pixels[x][y] = LOW;

}

void refreshScreen() {
  // iterate over the rows (anodes):
  for (int thisRow = 0; thisRow < 8; thisRow++) {
    // take the row pin (anode) high:
    digitalWrite(row[thisRow], HIGH);
    // iterate over the cols (cathodes):
    for (int thisCol = 0; thisCol < 8; thisCol++) {
      // get the state of the current pixel;
      int thisPixel = pixels[thisRow][thisCol];
      // when the row is HIGH and the col is LOW,
      // the LED where they meet turns on:
      digitalWrite(col[thisCol], thisPixel);
      // turn the pixel off:
      if (thisPixel == LOW) {
        digitalWrite(col[thisCol], HIGH);
      }
    }
    // take the row pin low to turn off the whole row:
    digitalWrite(row[thisRow], LOW);
  }

}

There is a more complex example in the Arduino playground. Other examples can be found on Tom Igoe's blog:

Tom's original version of this tutorial
Two matrixes on an Arduino Mega
Two-Matrix Pong

Tutorial.RowColumnScanning History

Row-columm Scanning to control an 8x8 LED Matrix

Row-columm Scanning to control an 8x8 LED Matrix

See Also:

Hardware Required

Row-columm Scanning to control an 8x8 LED Matrix

Circuit

Code