MC14489

Arduino library for controlling the MC14489, a 5-digit LED display driver capable of driving multiple common cathode 7-segment displays using a simple serial interface.

1. Installation

Method 1:

In the Arduino IDE:

1. Open LIBRARY MANAGER
2. Search phrase MC14489
3. Find the MC14489 by Ignacy110 library in the list
4. Click INSTALL

Method 2:

1. Download the repository as .zip file.
2. In the Arduino IDE, select: Sketch → Include Library → Add .ZIP Library...
3. Select the downloaded .zip file.

2. Connecting the MC14489 chip and pinout

Symbol	Pin	Description	I/O
f	1	f LED segments	output
e	2	e LED segments	output
VDD	3	Positive supply voltage (4.5V - 6.0V)	power
d	4	d LED segments	output
c	5	c LED segments	output
b	6	b LED segments	output
a	7	a LED segments	output
Rx	8	resistor connected between this pin and VSS (it sets the nominal display value)	analog input
BANK 1	9	first LED digit cathode	output
ENABLE	10	chip enable (active low)	input
CLOCK	11	clock signal	input
DATA IN	12	serial data input	input
BANK 2	13	second LED digit cathode	output
VSS	14	GND	power
BANK 3	15	third LED digit cathode	output
BANK 4	16	fourth LED digit cathode	output
BANK 5	17	fifth LED digit cathode	output
DATA OUT	18	serial data output (for cascading)	output
h	19	h LED segments	output
g	20	g LED segments	output

Communication uses a 3-wire interface:

• ENABLE (active low)
• CLOCK
• DATA IN

These three pins should be connected to Arduino digital pins defined in the code (see section 3.1).

3. Usage

3.1 Basic setup

Include this library <MC14489.h>.

Before using the library methods, you need to create an instance of the MC14489 class e.g. MC14489 ledDisplay(2, 3, 4); where the parameters denote pins: DATA, CLOCK, ENABLE. For readability you can define pins in advance using #define.

To operate the display correctly, you must initialize the transmission by calling the begin() method.

Example:

#include <MC14489.h> // include the library

#define ledDataPin 2 // define the Arduino pin number
#define ledClockPin 3 // define the Arduino pin number
#define ledEnablePin 4 // define the Arduino pin number

MC14489 ledDisplay(ledDataPin, ledClockPin, ledEnablePin);
// create an ledDisplay object using Arduino pins for communication with the MC14489

void setup()
{
  ledDisplay.begin(); // initialize communication
}

3.2 Use library methods

All available methods and their syntax are described in paragraph 4.

Simple example of use:

This program alternately displays the number 12345 and the text HELLO.

#include <MC14489.h> // include the library

#define ledDataPin 2 // define the Arduino pin number
#define ledClockPin 3 // define the Arduino pin number
#define ledEnablePin 4 // define the Arduino pin number

MC14489 ledDisplay(ledDataPin, ledClockPin, ledEnablePin);
// create an ledDisplay object using Arduino pins for communication with the MC14489

void setup()
{
  ledDisplay.begin(); // initialize communication
}

void loop()
{
  ledDisplay.clear(0); // clear the display
  ledDisplay.set(1,12345); // set the number 12345 starting from position 1
  ledDisplay.display(); // display
  delay(1000); // 1 second delay

  ledDisplay.clear(0); // clear the display
  ledDisplay.set(1,"HELLO"); // set the text "HELLO" starting from position 1
  ledDisplay.display(); // display
  delay(1000); // 1 second delay
}

Tip

More examples are in the examples folder.

4. Methods

Important

All methods provided by this library are member functions of the MC14489 class.
Therefore they must be called using the created object, for example ledDisplay.

4.1 Display refreshing

The display() method is used to refresh information on the display.

After calling this method, all changes made using set(), clear(), setDecimalPoint(), and setBrightness() are applied to the display.

4.2 Setting the number or characters on the display

The set(position, value, direction) method is used to set numbers and characters on the display.

Tip

A list of supported characters is available in paragraph 5.

This method is overloaded (there are four variants) and allows sending numbers or text, with optional left or right alignment.

This method takes two or three arguments:

No.	Argument name	Allowed values	Description
1	position	uint8_t - from 1 to 5	position from which characters or numbers will be written
2	value	int - a number that is in the range of the int type const char* - text (C-style string)	characters or numbers to be written (if a number or text has more characters than can fit on the display, it will be cut off)
3*	direction	bool - 0 or 1	Set text alignment to left (0 value - default) or right (1 value) relative to position * - you can omit this argument when calling the function - by default direction = 0

Specific prototypes of the set() function and examples of their use in practice (e.g. in the loop() function):

set() method prototypes	Example of use in practice	Example description
set(uint8_t position, int value)	set(2,123)	From the second position set the number 123 (left alignment from the second position)
set(uint8_t position, int value, bool direction)	set(5,840,1)	Set the number to 840, but the last character must be at position five (right alignment from the fifth position)
set(uint8_t position, const char* str)	set(3,"OFF")	From the third position set the text OFF (left alignment from the third position)
set(uint8_t position, const char* str, bool direction)	set(2,"o7",1)	Set the text to o7, but the last character must be at position two (right alignment from the second position)

Note

If the value exceeds the available display space, it will be truncated.

4.3 Clear display

The clear(bool value) method is used to clear the display.

Depending on the parameter, this method can clear the display in two ways:

value	Function
0	blank digits
1	all digits set to 0

4.4 Setting decimal points

The setDecimalPoint(uint8_t value) method is used to set dots - decimal points on the display.

The MC14489 chip allows you to set the displayed decimal points in 8 ways.

The value parameter controls which decimal points are enabled:

value	Function
0	no decimal points
1	decimal point after the first digit
2	decimal point after the second digit
3	decimal point after the third digit
4	decimal point after the fourth digit
5	decimal point after the fifth digit
6	decimal points after first digit and second digit
7	decimal points after all digits

Values greater than 7 are ignored.

4.5 Setting brightness

The setBrightness(bool value) method is used to set the display brightness.

The MC14489 chip supports two brightness levels: dim and bright.

The value parameter selects the brightness level:

value	Function
0	dim display
1	bright display

5. List of available characters

The MC14489 chip can display the following numbers and characters:

• numbers: 1, 2, 3, 4, 5, 6, 7, 8, 9, 0
• characters (in string): 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, A, b, C, d, E, F, c, H, h, J, L, n, O, o, P, r, U, u, y, -, =, *, space (" ")

Passing a character from outside this list to the set() method causes a space to be displayed.