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+--- Thread: Seven segment four digit led display (/showthread.php?tid=212)
Seven segment four digit led display - John - 12-11-2014
Here is a good article on using the ardiuno seven seg led displays:
http://www.electroschematics.com/10512/arduino-4-digit-7-segment-led-display/
The relevant code is a follows:
/*
* Arduino 4x7 LED Display
* Displays numbers ranging from 0 through 1023
* Test Code displays the value of a sensor connected to the analog input A0
* Inspired by a code found in the Arduino Cookbook
* Tested at TechNode Protolabz/July 2014
*/
// bits representing segments A through G (and decimal point) for numerals 0-9
const int numeral[10] = {
//ABCDEFG /dp
B11111100, // 0
B01100000, // 1
B11011010, // 2
B11110010, // 3
B01100110, // 4
B10110110, // 5
B00111110, // 6
B11100000, // 7
B11111110, // 8
B11100110, // 9
};
// pins for decimal point and each segment
// DP,G,F,E,D,C,B,A
const int segmentPins[] = { 13,8,7,6,5,4,3,2 };
const int nbrDigits= 4; // the number of digits in the LED display
//dig 0 1 2 3
const int digitPins[nbrDigits] = { 9,10,11,12 };
void setup()
{
for(int i=0; i < 8; i++) {
pinMode(segmentPins[i], OUTPUT); // set segment and DP pins to output
}
for(int i=0; i < nbrDigits; i++) {
pinMode(digitPins[i], OUTPUT);
}
}
void loop()
{
int value = analogRead(0);
showNumber(value);
}
void showNumber( int number)
{
if(number == 0) {
showDigit( 0, nbrDigits-1) ; // display 0 in the rightmost digit
} else {
// display the value corresponding to each digit
// leftmost digit is 0, rightmost is one less than the number of places
for( int digit = nbrDigits-1; digit >= 0; digit--) {
if(number > 0) {
showDigit( number % 10, digit) ;
number = number / 10;
}
}
}
}
// Displays given number on a 7-segment display at the given digit position
void showDigit( int number, int digit)
{
digitalWrite( digitPins[digit], HIGH );
for(int segment = 1; segment < 8; segment++) {
boolean isBitSet = bitRead(numeral[number], segment);
// isBitSet will be true if given bit is 1
// isBitSet = ! isBitSet; // Code Option*
// uncomment the above Code Option line for common anode display
digitalWrite( segmentPins[segment], isBitSet);
}
delay(5);
digitalWrite( digitPins[digit], LOW );
}
RE: Seven segment four digit led display - ABearden - 12-11-2014
Neat code!
If you want even more outputs for the same pinout, you could also toss a 4-bit address decoder on the digitPins output then pass an address out. It would net you 16 addressable 7-segments. If you're short cycles and want on-demand digit changing, 8-bit latches would help too; might add a bit to the circuit board though!