Arduino library for controlling seven segment 4 bit common anode LED display.
A 4 bit seven segment LED display has 12 pins - four of those are used for selecting a digit and the rest are used to light up a particular part of the segment. Each segment has a letter assigned to it, like in the image shown below.
Using the library is really easy. Different manufacturers use different pin layouts for their displays - so first you need to find the correct layout for your display model. Once you know the function of each pin, you can connect them to the Arduino board and create a LEDDisplay object in this simple manner:
#include <LEDDisplay.h>
LEDDisplay* myDisplay;
void setup() {
int segmentPins[] = {9, 7, 5, 3, 2, 8, 6};
int digitPins[] = {11, 10, 13, 12};
int decimalPoint = 4;
myDisplay = new LEDDisplay(segmentPins, digitPins, decimalPoint);
}
The constructor has three arguments - firstly an integer array containing the pins ordered by the segment they represent in this sequence: A,B,C,D,E,F,G. Then another integer array containing the pins that correspond to the digits in this order: Digit 1, Digit 2, Digit 3, Digit 4. The last argument is the pin that activates the decimal point.
In the example above pins 9, 7, 5, 3, 2, 8, 6 correspond respectively to segments A, B, C, D, E, F, G and pins 11, 10, 13, 12 correspond respectively to digits 1, 2, 3, 4.
Note that we use pins from the Arduino, NOT from the LED display itself. The pins from the LED are connected according to the segment/digit they activate.
If you are not sure or don't know how to hook up the LED to the Arduino, you can follow the instructions here.
clear() - Clears the display.
display(int) - Displays an integer in the range [0,9999], leading zeros are omitted.
display(int, bool[4]) - Displays an integer in range [0,9999] and sets the decimal point for each flag that is true. Each element in the array represents the decimal point for the corresponding digit. For example the element with index 1 in the array represents the second digit and so on. On a integer with N digits, only N decimal points can be set.
display(char[]) - Displays a symbol array with maximum of 4 elements. Note that not every symbol is representable in seven segment form, in such case the symbol in question is skipped.
display(char[], bool[4]) - Displays a symbol array with maximum of 4 elements and sets the decimal point for each flag that is true. Each element in the array represents the decimal point for the corresponding digit.
display(String) - Displays a string with maximum of 4 elements. Note that not every symbol is representable in seven segment form, in such case the symbol in question is skipped.
display(String, bool[4]) - Displays a string with maximum of 4 elements and sets the decimal point for each flag that is true. Each element in the array represents the decimal point for the corresponding digit.
The following code creates an LEDDisplay object and displays the word play for a brief period of time, then displays the number 7412 with decimal point set on digit 1 and 3.
#include <LEDDisplay.h>
LEDDisplay* myDisplay;
bool* arr = new bool[4] {true, false, true, false};
int segmentPins[] = {9, 7, 5, 3, 2, 8, 6};
int digitPins[] = {11, 10, 13, 12};
void setup() {
myDisplay = new LEDDisplay(segmentPins, digitPins, 4);
}
void loop() {
for (int i = 0; i < 100; i++) {
myDisplay->display("play");
}
for (int i = 0; i < 100; i++) {
myDisplay->display(7412, arr);
}
}
This library is inspired by a similar one by rastating that you can find here, but which had some limitations and I decided to write one on my own from scratch.