Free Project - 245 LED Display

[T.Jackson]

I realize that with my time here thus far I have offered little in terms technical assistance, PIC Basic snippets and so on.

So here's a nice BIG fish for everyone to cut their teeth on. A 245 LED, PC-programmable moving message display. Near-final cut, early last year the project was prototyped on two large PCBs and performed quite well. It's mandatory that high-intensity LEDs are used because the duty cycle is only around 2.8% for each column in the multiplex scheme. (Do NOT recommend expanding the display with more columns, the design is at its limits as is)

The component count is quite immense. This includes a 16f628, 24LC256 EEPROM, Max RS232, Decade Counters - 4017 variety, tonne of common passives, it'll take a couple of solid days work to put together. I can't offer the PCB layout sorry.

The zip file download includes schematics, micro controller source and Windows-based source written in Visual Basic 5.0, plus compiled executable. You will need the Virtual machine runtime DLL for the executable. This can be either msvbvm50.dll or msvbvm60.dll which are both freely obtainable.

Best Regards,
Trent Jackson

[Pic_User]

Hey Trent,

Thanks for the nice upload. You have included a lot of detailed information. We can learn a lot from the project. Interesting.

-Adam-

[T.Jackson]

I have also included a copy of the draft article - contains a modest amount of technical theory for the project. Sorry if some of you find it to be a bit of a hard read, it hasn't been proof read or edited, only been read by myself once or twice. In a technical sense I believe it to be accurate however.

I do sincerely hope that someone finds the project of interest, quite a fair bit of my time was poured into its development. The software was written in a matter of just a couple of days, but the overall hardware design did take some considerable time. It was intended to be published as a full scale project in the Silicon Chip magazine. Unfortunately however it won't ever go to print. Too expensive to build, too quirky to assemble, for a project like this to be successful it needs a double sided through-hole plated PCB a long with LED modules - not 245 individual LEDs.

All told, to make matters even more difficult, you can buy something like this pre assembled for under $100. It's just never gonna be this cheap for a KIT. But on the flip side of the coin, there is a nice learning aspect with building a big and useful project like this.

Trent Jackson

[Dazheng]

Hi Trent Thank you very much for posting your project. Its verrrry interesting project and I want to build one for myself.

[T.Jackson]

It's definitely worth building. Wish I still had my prototype. It was never returned to me.

[T.Jackson]

Turns out I will be getting my prototype returned, so I can offer technical support to those keen on building it.

[ismael b.]

HELLO TRENT

The OTHER SIDE Of the PCB is POSSIBLE SCANNEAR WHERE THEY ARE the COMPONENTS (CD4017, pic16f628, etc). OPPOSING SIDE OF THE COMPONENTS.

DEBTOR,


ISMAEL BRATTI BRAZIL

[T.Jackson]

Picture far right shows the main controller board with all associated digital circuitry. Suggest taking a closer look.

Far left - the display board which houses all 245 LEDs a long with column drivers
(Q1 - Q35). The display board is stacked on top of the controller board and wired accordingly. (see schematic) <br/>

[T.Jackson]

Someone has just brought to my attention that there's a missing dependency file in the download. This file is mscomm32.ocx and is required for serial communications. Unfortunately I can't include this in the download because I"m not licensed to do so.

You may obtain it here:
http://www.2ocx.com/show.php?ocx=mscomm32.ocx

<br/>

[Dan Cata]

Did you make a movie or something of the display working so we can see how it looks when ready? Mine is almost done!

[fazan83]

I realize that with my time here thus far I have offered little in terms technical assistance, PIC Basic snippets and so on.

So here's a nice BIG fish for everyone to cut their teeth on. A 245 LED, PC-programmable moving message display. Near-final cut, early last year the project was prototyped on two large PCBs and performed quite well. It's mandatory that high-intensity LEDs are used because the duty cycle is only around 2.8% for each column in the multiplex scheme. (Do NOT recommend expanding the display with more columns, the design is at its limits as is)

The component count is quite immense. This includes a 16f628, 24LC256 EEPROM, Max RS232, Decade Counters - 4017 variety, tonne of common passives, it'll take a couple of solid days work to put together. I can't offer the PCB layout sorry.

The zip file download includes schematics, micro controller source and Windows-based source written in Visual Basic 5.0, plus compiled executable. You will need the Virtual machine runtime DLL for the executable. This can be either msvbvm50.dll or msvbvm60.dll which are both freely obtainable.

Best Regards,
Trent Jackson

Trent Jackson,
I am really interested with your project but can you please post the code here?
I want to see the code and try to understand it.
That is the best way for me to understanding your design.

If cannot then fine.


Thanks in advance.

Ops sorry I just found the code here.

Sorry for not looking the file properly.
I will try this and ask you if I have any question.

Thanks

[T.Jackson]

Everything is in the d/l - if you have any queries then just post them here.

[Dan Cata]

Dear Trent, i have recently installed Win XP on my comp and copyed MSCOMM32.OCX in sys32 (VB not installed) ; the aplication runs but when i press "program messege to eeprom" button, i get an Communications error "Port already in use or doesn't exist ; Chose a different port " but the com1 is free; what do i do?

[T.Jackson]

Apart from suggesting that you try another comm port, it's hard-to-say because everything works fine on my end. I have Win XP with service pack 2. If there was a problem MSCOMM32.OCX, the program wouldn't run at all. So you can rule that out.

[magu]

I have build my led matrix from the start to finish. and i have some problems... I finaly programmmeed the PIC and when i connect the 5V and the 12V and the Serial Port, and when i bush the button for program LED it doesen`t stay ON (lighting).I start the VB program to sent EEPROM the informations but when finished nothing happens. I have a link with the sheme that i construct... i hope you can help me... THX.. I will wait for your answer.

http://www.zamfirelu.org/lm.jpg

[Bronx68]

Please explain the use of D3 through D7 do make an 'or gate' for reset. Why 100K resistors?
Why not use Q0 from each of the CD4017 counters?

[falingtrea]

Please explain the use of D3 through D7 do make an 'or gate' for reset. Why 100K resistors?
Why not use Q0 from each of the CD4017 counters?

The diodes are used to create a master reset from the PIC and to isolate each 4017's reset from each other. Diodes are usually a lot cheaper than logic for something as simple as this. The 100k is probably on the conservative side as far as a value, unless the designer was trying to reduce race conditions or output glitches by creating a simple RC filter.

[T.Jackson]

The diodes are used to create a master reset from the PIC and to isolate each 4017's reset from each other.

Correct!

Further explanation -- without the diodes intact, Q0 lines on the counters wouldn't have control over their designated MR line. You simply can't tie all the Q0 lines together with anything but a semiconductor for this. As for the 100K resistors -- these ensure that there's never going to be a short between RB5 on the PIC and associated Q0 lines on the counters. When RB5 swings high, any of the Q0 lines on the counters could be either high or low. This is CMOS we're talking about here, we could even go as high as a mega ohm.

[inspired4real]

HELLO T JACKSON, YOUR PROJECT IS INSPIRING AS IF TO SAY CHALLENGING SO MANY PEOPLE AROUND THE WORLD. I WANT TO BUILD THIS PROJECT AND MAGUS SITE TENDS NOT TO OPEN AND IT IS LIKE IT IS NOT IN ENGLISH(SORRY TO MAGU IF I AM WRONG). I AM THOUGH A NEWBIE TO PIC IN SOME SENSE BUT HAVE BEEEN PLAYING WITH ANALOG ELECTRONICS FOR SOMETIME. WHAT I DONT REALLY UNDERSTAND IS THE EEPROM ASPECT OF YOUR PROJECT, I WANT TO KNOW HOW YOU LOAD THE ASCII CHARACTER SET INTO THE EEPROM FROM YOUR PROGRAM, OR ARE YOU NOT USING THAT METHOD. I WAS THINKING OF DEFINING EEPROM ADDRESSES FOR ASCII CHARACTER AND THEN LOADING EACH CHARACTER IN AN ADRESS THAT I WILL LATER READ TO DISPLAY CHARACTER. DO YOU HAVE ANY DETAIL MATERIALS ON HOW TO USE EERPOM LIKE THE ONE YOU USED IN THE PROJECT? HOW FAST REALLY DO YOU FETCH DATA FROM THIS EEPROM . I AM THINKING OF BUILDING A BIGGER DISPLAY USING 3mm ULTRABRIGHT LED WITH BUFFER AND SUPPLYING ABOUT 50ma OF CURRENT WITH MULTIPLEXING I DONT THINK THE LEDS WILL GET DAMAGED? SORRY REALLY IF MY QUESTION MAY BE TOO SIMPLE FOR YOU TO REPLY TO?
IS THERE ANYWAY I CAN GET MAGU'S LINK AND DOWNLOAD HIS STUFF. THANKS.

[T.Jackson]

The ASCII characters are custom, specific only to this project. They are programmed into the eeprom one byte at a time, whereas each byte represents data for the column in the character. Each column of data for a character is assigned a unique address in the eeprom and all the columns are collated together to form the character. It is impossible to explain the entire inner workings of the system in just a few paragraphs. I don't recommend this project for anyone who is new to pics / electronics.

Regards,

Trent Jackson

[yupng]

i need a software and hardware about dot matrix message display using wireless keyboard.
Use wireless keyboard to sent the data to dot matrix message display....
Anyone can help me???
Pls.........

[skimask]

i need a software and hardware about dot matrix message display using wireless keyboard. Use wireless keyboard to sent the data to dot matrix message display.... Anyone can help me??? Pls.........

Don't ask for much do ya...

What is your skill set?

Which PIC do you want to use?

What sort of hardware would you like to use?

What kind of wireless transmission protocol are you planning on using?

Lost yet?

Try eBay...

[yupng]

Don't ask for much do ya...

What is your skill set?

Which PIC do you want to use?

What sort of hardware would you like to use?

What kind of wireless transmission protocol are you planning on using?

Lost yet?

Try eBay...

What i want is use two microcontroller(MCU) to build this project. One MCU is connect to PC keyboard and transmitter(using RF or IR to transmit the data).Another MCU connect to receiver(can be IR or RF circuit) and dot matrix. I found one similar project but i cant found the datesheet for the MCU used in this project. I also don't understand the code.

[skimask]

What i want is use two microcontroller(MCU) to build this project. One MCU is connect to PC keyboard and transmitter(using RF or IR to transmit the data).Another MCU connect to receiver(can be IR or RF circuit) and dot matrix. I found one similar project but i cant found the datesheet for the MCU used in this project. I also don't understand the code.

And didn't answer ANY of the previous questions...

[yupng]

And didn't answer ANY of the previous questions...

i still doing the research for this project. So i not confirm what hardware are require for this project. I hope anyone has this similar project can post it to me. Actually my project topic is <Wireless Announcement Board>.
Any information that related to this project also can post to me.
Thanks.......

[selim]

HI T.Jackson

can you please tel me the modification in the code to work with 74hc164

Thank you in advance

[aladdin_2005]

hi t.jackson

we built ur project ,but we face some problems..
first we changed the eeprom type to (24lc16b) -256 is not avaible
but there was no thing working no message on the screen
and one thing more...
the eeprom when programmed by the serial and the pic (this stuff)
when we read it on our computer only one address changes the first one only..!

just wanted to know something too where the programme start writing on the eeprom (which address) .

i wonder if i continued working with this eeprom (24lc16b) should i change the software (the pic software).

Thanx in advance