project: built a 7x10 led matrix module

MATRIXDOBLE30L.JPG (39854 bytes)



Easy to build. Test and application programs available.

Watch video!

Features of project: 7x10 leds matrix module implemented with two 7x5 modules. Direct connection without wires to 14 pin LCD connector, for Bolt 18F2550 and Bolt v.Lite.

The module may be connected to a standard LCD interface, so your system may work either with LCD, a seven segment display or a 7x10 led matrix module.

4 test and application programs are included: shows two numbers, a decimal counter 00 to 99, to display a message with scrolling in columns and to display a random number.



The module uses the time multiplexing technique to turn on the LED patterns and form letters, numbers and graphics.

Complete libraries are provided with patterns to show numbers, letters, symbols and graphics.

in the picture at left a graphic character is shown. 2 graphic characters are provided in libraries: an arrow and a heart. Library with complete set of patterns is:


Please consult the table shown below to see complete set of characters available in this library.



The design of the circuit is based on two 7x5 GMM-12057ASB modules.  The 14-pin connector is compatible with signals of Bolt 18F2550.

The operating principle of the double matrix of 7x10 uses a technique of time multiplexing to display characters on the display.

RA1 and RA2 are used to control a 4017 Johnson counter while RB1...RB7 output the character patterns in the columns of LEDs.

10 BC337 transistors are used to activate each column. The transistors are triggered one a a time by the Johnson counter.

Electronic diagram here: matrix7x10.pdf


The character set for the 7x10 matrix modules is the following:

library: LETRASCCS3.h

-Letters A...Z, including “”

-Letters a...z, including “”, and vocals with accent: , , , , .

-Numbers 0...9

-The following symbols:  







2 Graphics:









 -       2 graphic symbols: ARROW AND HEART

-         To show an ARROW, type “%&” in program.

-         to show a HEART, type “/(“.

-         Both symbols are shown in a matrix of 7x10

Module may be connected directly to the 14 pin LCD port, either to Bolt 18F2550 system, or Bolt v.Lite module as shown.

4 application programs available here:



C-18-MATRIX-7X10-DECIMAL-COUNTER.c Decimal counter 00..99
C18-MATRIX-7X10-RANDOM-NUMBER-GENERATOR.c Random number generator. After reset, shows a random number in 2 digits. User may modify program to change speed.
C18-MATRIX-7X10-SHOWS-2-CHARACTERS.c Shows 2 characters, letters, graphics or numbers
C18-MATRIX-7X10-MESSAGE-WITH-SCROLLING.c Shows horizontal scrolling message
LETRASCCS3.h Library with letters, numbers and graphics patterns, version 3
LETRASCCS2.h Library with letters and numbers patterns, version 2
18F2550BOLT.h Universal Bolt 18F2550 library