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Join Date: Aug 2011
Posts: 4

Dot Matrix

04/12/2012 2:24 AM

Hi,

We have just started subject of micro controller, and I want to display an alphabet in dot matrix. But I am confused how to control individual LEDs?

I can only control LEDs row wise or column wise.

If some one knows the code please guide me.. and yes programming should be in c++.

Thanks.

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#1

Re: Dot Matrix

04/12/2012 4:18 AM

what kind of controller are you using? are you using a led matrix or individual multiplexed LED's? more info please

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#5
In reply to #1

Re: Dot Matrix

04/13/2012 4:01 AM

oh sorry i forgot to mention.

i am using Atmel 89s52 and yes i am using led matrix.

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#2

Re: Dot Matrix

04/12/2012 4:48 AM

you got to check with the manufacturer of such matrix, for them to provide the control code!

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#3

Re: Dot Matrix

04/12/2012 8:09 AM

Please give the manufacturer and part number of your display device (LED array).

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Participant

Join Date: Apr 2012
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#4

Re: Dot Matrix

04/12/2012 12:50 PM

What type of microcontroller you have ?

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#6

Re: Dot Matrix

04/13/2012 4:31 AM
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#7

Re: Dot Matrix

04/15/2012 4:13 PM

Hi there I did a similar thing with a picaxe 28x chip and no driver circuitry or resistors (the pic didn`t blow up and worked quite happily) so it was relatively simple but not quite as bright as the commercial displays. Basically you use one of the microprocessor ports to drive the outputs or columns in the display and you wire all of the rows to another port also configured as output . So for an 8x8 array sending binary 10000000 to the output port a (columns) and 11111110 to port b (rows) will light 1 of your 64 leds. To get patterns manipulate the output and inputs e.g port a = 255 (11111111) and port b 0 (00000000) turns all 64 leds on. However you will soon see that certain patterns are not available directly so you must drive each column one at a time in a loop whilst feeding in the row information for that character as an 8 bit number. I used the memory on the chip to store the data and then read it in using a read or peek command. Likewise I wrote a program to convert the patterns to binary on a PC. If you want to get more complex you must use driver chips, serial data and shift registers so it can get very messy for a beginner.

http://www.youtube.com/watch?v=WRVsccpUWmA

This shows a 7x5 and 4x4 arrays I used some time ago.

Shows what you can do with minimum equipment but as for programming in C your on your own there I used basic.

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