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Led Message controler

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Hello All.... I have an LED rolling Message board. Its consist of P16V51RD is the main controller.. also 74LS138, 74H595 na d24C64, HT1380 and 74LS138...

any one know aboout the 16x8 Led board

Thank you

previous thread said:
I have a moving message dispplay with controller P89V51RD with HT1380 Timer chip. Its also have 74HC245 and 2 nos of 74LS138, 74HC595and AT24C64. its controlled by PS2 keyboard.. But now, the programme of the P89V51RD is correpted.. have any one with the same HEX file for the P89V51RD?

Thanks in advance...
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Here is a thread from EDA discussing similar project like yours.
Thank you absf.

Its is the same type of mine... I have the circuit, But I dont have the source.. I cant login the website you shared.. A Baned message will appeir when I log in... Any Idea to fix my problem?

Thank you again..


Active Member
Not sure why you cant get into the link. May be you need to register in order to read that info.

May be you need to register in order to read that info.
I cant registered again with my IP... Its showing an error.

Can you do it me for a favor?

Can you sign in there and provide all attachement in that thread...?

Thanking You

Manoj Soorya
I cant see any attachment in that threads... its is difficult to view the attachment without login... If I login, it shows "

"You have been banned for the following reason:
Repeated Posting of Duplicate Threads and Posts

Date the ban will be lifted: Never"

You can upload the files to

Its is free. I hope you can help me..

Thank you absf...


Active Member
Here's the post from Okada:
This is the circuit I have been given for reverse engineering.

It has a 4 feet matrix display.

It has other features like RS232 input, PS2 Keyboard input, HT1380 RTC, 24C64 EEPROM not shown in circuit.

Now the issue is only with matrix display code writing. How should I approach ?

The original board uses P89V51RD2 which is obsolete and the chip on board is defective. I am going to replace it by At89S52 as the code seems to fit in it (checked by creating 16x16 matrix font data for 100 charcaters, uses 1% of ROM)

As rows are less, should I use row scanning ?

That is place colums Data on columns and then turn on row 1 for a few ms and then turn off row 1
then turn on row 2 for a few ms and turn it off
continue like this till all 16 rows are scanned.

Is there any better and efficient approach ?

There are 12 HC595s. They are divided into 2 groups (6 + 6)

How is data transferred to it ?

Data to each 6x HC595 blocks gets transferred at the same time using same SH_CP and ST_CP ? I guess, yes.
Data for the two HC595 bloacks are placed on A4 and A5 (bit by bit) of LS245 and A7 and A6 of LS245 are used for SH_CP and ST_CP clocks. Right ?

What about Rows ?

They are just turned ON and OFF that is 2 rows (like row 1 and row 9) at the same time ? So, with 8 different selections of HC138 all 16 rows gets scanned ?

What about scrolling ? Data is divided into 2 blocks in column. How should I write code for scrolling message. How does data of column block 2 changes to column 1 block data ?

Looking at the HC138 outputs, cathodes of the displays are connected to rows ?
okada_1 001.jpg okada_1 002.jpg


Nice and thank you for sending this circuit for me.... I have the original diagram...

any hope to get the code for this schematic?


Active Member
If you have the PCB, you can find a way to read the hex codes embedded inside. If the code is protected, I guess the only way is to do reverse engineering and write your own code that would make the circuit work as intended just like what Okada is doing.

Dont think this is a simple piece of job even for the experienced people here; me not included. I am just a hobbist like you...

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Thank you absf for your replay..... Its code is protected.. I try to read. So I now searching internet for that.. I think I can find one for the same, But I need more time...

I previously say that, "you can got anything from internet, but you can't get your Dad and Mom. But I now say, extend your time for searching extra five minute, you can also get them.."

I really Belive my words, I have many reason....many reson...

anyway thank you for your kind attenssion in my post and help........
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