Tutorial.BarGraph History

Hide minor edits - Show changes to markup

April 10, 2014, at 05:15 PM by Roberto Guido - added a potentiometer in the list of required hardware. Thanks to Kris for the alert
Added line 16:
  • (1) Potentiometer
May 02, 2012, at 04:04 PM by Scott Fitzgerald -
Changed lines 38-39 from:
to:
November 16, 2011, at 04:20 AM by Scott Fitzgerald -
Changed lines 38-39 from:
to:
September 23, 2010, at 10:43 PM by Christian Cerrito -
Added lines 3-4:

LED Bar Graph

September 19, 2010, at 09:35 PM by Christian Cerrito -
Changed line 49 from:
  • Array: a variation on the For Loop example that demonstrates how to use an array.
to:
  • Array - a variation on the For Loop example that demonstrates how to use an array.
Changed line 51 from:
to:
September 19, 2010, at 09:34 PM by Christian Cerrito -
Changed line 37 from:
to:
Added lines 39-51:

See Also:

September 19, 2010, at 09:20 PM by Christian Cerrito -
Changed lines 5-6 from:

This tutorial borrows from the For Loop and Arrays tutorial as well as the Analog Input tutorial.

to:

This tutorial borrows from the For Loop and Arrays tutorial as well as the Analog Input tutorial.

September 19, 2010, at 08:44 PM by Christian Cerrito -
Added lines 11-17:

Hardware Required

  • Arduino Board
  • (1) LED bar graph display or 10 LEDs
  • (10) 220 ohm resistors
  • hook-up wire
  • breadboard
September 19, 2010, at 08:08 PM by Christian Cerrito -
Changed lines 24-25 from:
to:
September 16, 2010, at 10:20 PM by Tom Igoe -
Changed line 29 from:
to:
February 24, 2010, at 04:32 AM by Tom Igoe -
Changed line 29 from:
to:
February 24, 2010, at 04:31 AM by Tom Igoe -
Changed lines 29-47 from:
 /*
   LED bar graph
  
   Turns on a series of LEDs based on the value of an analog sensor.
   This is a simple way to make a bar graph display. Though this graph
   uses 10 LEDs, you can use any number by changing the LED count
   and the pins in the array.
   
   This method can be used to control any series of digital outputs that
   depends on an analog input.
  
   The circuit:
    * LEDs from pins 2 through 11 to ground
  
  created 26 Jun 2009
  by Tom Igoe 
  
  http://www.arduino.cc/en/Tutorial/BarGraph
  */
to:
Deleted lines 30-67:
 // these constants won't change:
 const int analogPin = 0;    // the pin that the potentiometer is attached to
 const int ledCount = 10;    // the number of LEDs in the bar graph

 int ledPins[] = { 
   2, 3, 4, 5, 6, 7,8,9,10,11 };   // an array of pin numbers to which LEDs are attached

 void setup() {
   // loop over the pin array and set them all to output:
   for (int thisLed = 0; thisLed < ledCount; thisLed++) {
     pinMode(ledPins[thisLed], OUTPUT); 
   }
 }

 void loop() {
   // read the potentiometer:
   int sensorReading = analogRead(analogPin);
   // map the result to a range from 0 to the number of LEDs:
   int ledLevel = map(sensorReading, 0, 1023, 0, ledCount);

   // loop over the LED array:
   for (int thisLed = 0; thisLed < ledCount; thisLed++) {
     // if the array element's index is less than ledLevel,
     // turn the pin for this element on:
     if (thisLed < ledLevel) {
       digitalWrite(ledPins[thisLed], HIGH);
     } 
     // turn off all pins higher than the ledLevel:
     else {
       digitalWrite(ledPins[thisLed], LOW); 
     }
   }
 }

August 27, 2009, at 08:57 PM by Tom Igoe -
Added lines 17-19:

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

July 05, 2009, at 07:49 PM by Tom Igoe -
Changed lines 24-31 from:

[@ /*

  LED bar graph

  Turns on a series of LEDs based on the value of an analog sensor.
  This is a simple way to make a bar graph display. Though this graph
  uses 10 LEDs, you can use any number by changing the LED count
  and the pins in the array.
to:
Changed lines 26-27 from:
  This method can be used to control any series of digital outputs that
  depends on an analog input.
to:
 /*
   LED bar graph
  
   Turns on a series of LEDs based on the value of an analog sensor.
   This is a simple way to make a bar graph display. Though this graph
   uses 10 LEDs, you can use any number by changing the LED count
   and the pins in the array.
   
   This method can be used to control any series of digital outputs that
   depends on an analog input.
  
   The circuit:
    * LEDs from pins 2 through 11 to ground
  
  created 26 Jun 2009
  by Tom Igoe 
  
  http://www.arduino.cc/en/Tutorial/BarGraph
  */
Deleted lines 45-46:
  The circuit:
   * LEDs from pins 2 through 11 to ground
Changed lines 47-48 from:
 created 26 Jun 2009
 by Tom Igoe 
to:
 // these constants won't change:
 const int analogPin = 0;    // the pin that the potentiometer is attached to
 const int ledCount = 10;    // the number of LEDs in the bar graph
Changed lines 51-90 from:
 http://www.arduino.cc/en/Tutorial/BarGraph
 */

// these constants won't change: const int analogPin = 0; // the pin that the potentiometer is attached to const int ledCount = 10; // the number of LEDs in the bar graph

int ledPins[] = {

  2, 3, 4, 5, 6, 7,8,9,10,11 };   // an array of pin numbers to which LEDs are attached

void setup() {

  // loop over the pin array and set them all to output:
  for (int thisLed = 0; thisLed < ledCount; thisLed++) {
    pinMode(ledPins[thisLed], OUTPUT); 
  }

}

void loop() {

  // read the potentiometer:
  int sensorReading = analogRead(analogPin);
  // map the result to a range from 0 to the number of LEDs:
  int ledLevel = map(sensorReading, 0, 1023, 0, ledCount);

  // loop over the LED array:
  for (int thisLed = 0; thisLed < ledCount; thisLed++) {
    // if the array element's index is less than ledLevel,
    // turn the pin for this element on:
    if (thisLed < ledLevel) {
      digitalWrite(ledPins[thisLed], HIGH);
    } 
    // turn off all pins higher than the ledLevel:
    else {
      digitalWrite(ledPins[thisLed], LOW); 
    }
  }

}

@]

to:
June 26, 2009, at 09:22 PM by Tom Igoe -
Added lines 9-10:

http://media.digikey.com/photos/Lite%20On%20Photos/LITE-ON%20INC-%20LTA-1000G.jpg

June 26, 2009, at 09:20 PM by Tom Igoe -
Changed lines 3-4 from:

The bar graph - a series of LEDs in a line, such as you see on an audio display - is a common hardware display for analog sensors. It's made up of a series of LEDs in a row, an analog input like a potentiometer, and a little code in between. This tutorial demonstrates how to control a series of LEDs in a row, but can be applied to any series of digital outputs.

to:

The bar graph - a series of LEDs in a line, such as you see on an audio display - is a common hardware display for analog sensors. It's made up of a series of LEDs in a row, an analog input like a potentiometer, and a little code in between. You can buy multi-LED bar graph displays fairly cheaply, like this one. This tutorial demonstrates how to control a series of LEDs in a row, but can be applied to any series of digital outputs.

June 26, 2009, at 09:14 PM by Tom Igoe -
Changed lines 5-79 from:

This tutorial borrows from the For Loop and Arrays tutorial as well as the AnalogInput tutorial.

to:

This tutorial borrows from the For Loop and Arrays tutorial as well as the Analog Input tutorial.

The sketch works like this: first you read the input. You map the input value to the output range, in this case ten LEDs. Then you set up a for loop to iterate over the outputs. If the output's number in the series is lower than the mapped input range, you turn it on. If not, you turn it off.

Circuit

click the image to enlarge

Schematic:

click the image to enlarge

Code

/*
  LED bar graph

  Turns on a series of LEDs based on the value of an analog sensor.
  This is a simple way to make a bar graph display. Though this graph
  uses 10 LEDs, you can use any number by changing the LED count
  and the pins in the array.

  This method can be used to control any series of digital outputs that
  depends on an analog input.

  The circuit:
   * LEDs from pins 2 through 11 to ground

 created 26 Jun 2009
 by Tom Igoe 

 http://www.arduino.cc/en/Tutorial/BarGraph
 */


// these constants won't change:
const int analogPin = 0;    // the pin that the potentiometer is attached to
const int ledCount = 10;    // the number of LEDs in the bar graph

int ledPins[] = { 
  2, 3, 4, 5, 6, 7,8,9,10,11 };   // an array of pin numbers to which LEDs are attached


void setup() {
  // loop over the pin array and set them all to output:
  for (int thisLed = 0; thisLed < ledCount; thisLed++) {
    pinMode(ledPins[thisLed], OUTPUT); 
  }
}

void loop() {
  // read the potentiometer:
  int sensorReading = analogRead(analogPin);
  // map the result to a range from 0 to the number of LEDs:
  int ledLevel = map(sensorReading, 0, 1023, 0, ledCount);

  // loop over the LED array:
  for (int thisLed = 0; thisLed < ledCount; thisLed++) {
    // if the array element's index is less than ledLevel,
    // turn the pin for this element on:
    if (thisLed < ledLevel) {
      digitalWrite(ledPins[thisLed], HIGH);
    } 
    // turn off all pins higher than the ledLevel:
    else {
      digitalWrite(ledPins[thisLed], LOW); 
    }
  }
}


June 26, 2009, at 09:09 PM by Tom Igoe -
Added lines 1-5:

Examples > Display

The bar graph - a series of LEDs in a line, such as you see on an audio display - is a common hardware display for analog sensors. It's made up of a series of LEDs in a row, an analog input like a potentiometer, and a little code in between. This tutorial demonstrates how to control a series of LEDs in a row, but can be applied to any series of digital outputs.

This tutorial borrows from the For Loop and Arrays tutorial as well as the AnalogInput tutorial.

Share