led dot matrix urgent

Thread Starter


Joined Dec 17, 2006
Hi every one:D ;
i am new to this forum and i am currently undertakin an electrical engineering degree and i thought it would be a good idea to join.
I have a problem to program the pic 18f4620 to control the led dot matrix. Actually I have to design the led billboard just like display at outdoor. Firstly, I just wanna to learn how to control the led dot matrix 7x5(juz 1 frame for 1 character)..but its not success. For ur information Im using pic18f4620 and shift register(74hc595) to shift the data(spi concept)..i also using MicroC compiler to write my program(c programming)..
For example I want to display the character R and it will scrolling (moving to the left).i already attach fail for discription about my project.anybody can help me??



Joined Feb 3, 2008
can you help me by explain how to coding the programme to show capital letter 'A' .Maybe u can tell me the concept how its work


Joined Dec 27, 2007
Usually, billboards use a column select, then activate the rows in order to display a single line (part of a letter). Then, the column is incremented, then another line is displayed. This is done quickly and is part of a loop structure. You need look-up tables to create the letters out of individual lines.

Your method is a bit confusing. It seems a bit more tailored to using large displays, since you're using 3 outputs from your microcontroller, plus a lot of unnecessary complexity, to achieve what you can do easily with two more outputs.

You need to do this line by line. So, write a single column, send the serial data to write a 00000001. Write the next column, send 00000010, etc. Try to find an elegant way to do this in a loop structure, so that you can use it for larger arrays of letters.