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Help me to display a message from PC on LED Message Board

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Newbie level 4
Feb 9, 2006
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I'm doing a project on LED message board. It's only part of my project title. My title required me to write a PC simulation program on LED message board with 3 effects and 3 size selctions. The second part is the LED message board itself, then the third part is the wireless upload from the PC to the LED message board.

I've almost done my first and third parts of my title request, but when it comes to the LED message board, my brain's becoming blank!!! I got a circuit diagram from, but I have no clue how it runs as a whole? I basically know how the shift register work but when it's connected to the microcontroller, all starts confusing. Yet, I'm not that good in assemble programming, thinking of using C or mikroBasic but still, I'm not sure how the port pins should run???

I still have a month before the due date of my project, so PLEASE HELP me!!! It's not necessary to be the circuit I found above, if you have any better suggestions, please share with me!!!

74hc595 mikrobasic


A good place to start :

**broken link removed**

**broken link removed**

hope it'll help!
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Re: LED Message Board!!!

I don't see anything wrong with the schematic you have found, but it would be beneficial for you if you practised a little bit on simpler circuits containing less diodes; here are examples of circuits and software in PICBASIC:


LED Message Board!!!

Thanks for the suggestions, but can you tell me how the microcontroller and shift register 74HC595??? How the PortA pin 1 to pin 3 work in this case??? When should it be active high or low??? Just a simple algorithm will do!!!

LED Message Board!!!

i would suggest u use C or picbasic pro for ur project... so u can left those redundant stuff to b done by the compiler n u can concentrate on ur algorithm...

mostly this type of chift register is quite simple to use... mostly is clk, strobe, enable, data...

as it name imply, the clk is the shifting clk..... strobe is like latch when u assert this strobe, data will capture... the enable is to let u ON or OFF the output pin... data is those pin connect to the LEDs which to b ON or OFF...

wth PICBasic Pro, there is the "shiftout" instruction u can use wth this type of shift register... this instruction is built for for this type of shift register.. very convenient

if u are using CCS C, then shift_left() or shift_right() is almost the same as the "shiftout" but more things to control... C let u hav more control on ur program... in my humble opinion..

try it first then mayb i can help..


Re: LED Message Board!!!

I've read the webpage you provided, thanks for that!!!

But can anyone look at the circuit and provide me some simple algorithm or program that works on the circuit I post? I just need an clear idea on how to light up a character "R" or others on this circuit.

Re: LED Message Board!!!

I have already use 74HC595 and it works fine except one thing....
when i tried to scan it, it looks like leave some little track... some led supposed to be off but it turned on,but not as bright as the others. Did someone have experienced the same problem? , i using 4 74HC595 in series to drive 4 dot matrix. Thanks a lot for your help.

Best regards

LED Message Board!!!

Can someone donate so points to me??? I've try to access to some useful pages suggested, some in this forum, but I done have enough points to view the necessary information!!!

Re: LED Message Board!!!

You need to know the programming of microcontroller and a little idea of hardware design. You can use At89s52 for this as it has ISP so easy to debug. If you want me to help you mail me with your total project plan probably I will be able to send you total solution.

mail me to

With regards
Rituparna Saikia

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