Briel Computers Forum

fsafstrom · Joined: 26 Dec 2006 Posts: 155 Location: San Antonio, Texas

I guess you are never a true geek until you have written a Game of Life program. Cool

Just to stand out of all the other geeks, let's write it in 6502 Assembler on a computer most people never heard on and on top of that, add a homebrew hardware that took months to build. Very Happy

It's quite simple, hook up a 6522 VIA and map it to address $C040.
See thread, http://www.brielcomputers.com/phpBB2/viewtopic.php?t=190

Get an old ATX power supply (since I had one lying around) and convert it to a poor mans Lab supply.
http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply

Then order some 8x8 LED units from China for $23 and wait one month to get them.
During this time, order free samples from http://www.maxim-ic.com/, it took me 4 months to get 10 Max7219... Rolling Eyes

They won't send you 10 of these puppies at once so just keep ordering...

Then get a few more parts for around $30 and spend another month soldering...
At the end, you will have a beautiful 24x24 LED display...

Testing the display:

The setup running game of life:

The not-so-easy-to-debug side of the board:

Here is a short Video I put on Photobucket:

Want your own replica ?
Check it out here => http://www.brielcomputers.com/replica1.html

And the 6502 assembler for your Replica,

fsafstrom · Joined: 26 Dec 2006 Posts: 155 Location: San Antonio, Texas

I just had to take a break before I document how this thing works...

The 24x24 LED display is actually nine 8x8 LED units.
Each 8x8 unit is controlled by a MAX 7219 LED driver, if you look at the test I made, you can see how they are organized.
So that is basically LED unit 1-9 from top left to bottom right.
The Max 7219 keeps track of which LEDs I want to light up, so I only need to send the data once and then the chip will do the rest for me.
Each row (cathode) in the LED unit is connected to the digit section on the Max 7219 and each column (Anode) to the Segment section.
The Max 7219 accepts serial data so the chips are daisy chained together, however the clock and latch are parallel and goes to all chips in parallel.
Data basically flows from one chip to another so the most efficient way of sending data is to send 9 commands in a row and then latch it (tell the driver to use the data).
So when sending graphical data, you send 9 columns and then latch it.
Then row two, three and so on to row 8.

The VIA (6522) have a shift register so it's really doing a lot of work for me, all I need to do is load the shift register and tell it to send the data to the Max 7219.

Let me know if you have any questions or comments.

MAX 7219 Datasheet,
http://datasheets.maxim-ic.com/en/ds/MAX7219-MAX7221.pdf

cheese1113 · Joined: 13 Nov 2005 Posts: 91 Location: Reedley, CA

That is awesome! I think that there is potential for games with this set up!!
_________________
Max Wooden

fsafstrom · Joined: 26 Dec 2006 Posts: 155 Location: San Antonio, Texas

Yes, there will soon be a LED Pong game, maybe with a SID 6581 for sound effects or a SoundGin...
IF I can get the SoundGin to work that is, they don't seem to work to well on solderless breadboards... Sad

cheese1113 · Joined: 13 Nov 2005 Posts: 91 Location: Reedley, CA

You made Hack A Day! http://www.hackaday.com/2007/04/25/my-motors-finally-came-extra/
_________________
Max Wooden

fsafstrom · Joined: 26 Dec 2006 Posts: 155 Location: San Antonio, Texas

I actually sent the link to Hack a day...
I'm glad they picked it up.

Here is a short Video I put on Photobucket:

ethan · Joined: 02 May 2007 Posts: 1

Very nice. I can probably figure it out the hard way by inspecting the code, but how did you attach the 6522 to the array of 7219s? I'm guessing CB2 is data-in to the first 7219, but what are the other pin assignments?

Thanks and congrats on this. I need to track down a pile of LED matrices. I already have a few 7219s on hand.

-ethan

fsafstrom · Joined: 26 Dec 2006 Posts: 155 Location: San Antonio, Texas

Hi Ethan,

The Load data (pin 12) on Max 7219 is connected to PA0 (pin 2) on the 6522.
Clock (pin 13) on Max 7219 is connected to CB1 (pin 18 ) on the 6522.
Data In (pin 1) on Max 7219 is connected to CB2 (pin 19) on the 6522.

The VIA (6522) is setup with port A as output and for the shift register to shift out at the pace of Phi2.

logjam · Joined: 15 May 2007 Posts: 14

I LOVE a project with LEDs! Smile

Here is a picture of mine:

Front: http://www.stockly.com/images2/060129-LED_Display_Front_2718.jpg

Back: http://www.stockly.com/images2/060129-LED_Display_Back_2716.jpg

Legs: http://www.stockly.com/images2/060129-Weight_of_39584_Legs_2696.jpg

I have not built the driver circuits. I only finished it to win a bet (which had no wagers). I averaged 3.5 hours per 990 LED board. Smile

I plan to make a new one with finer pitch LED MODULES. Like your modules, with a .3" pitch. My display has a .4 inch pitch.

I built it for my Altair and Apple-1. The only thing I know is ALL the LEDs are in correctly and all light up. Smile

fsafstrom · Joined: 26 Dec 2006 Posts: 155 Location: San Antonio, Texas

Now that's an LED display... Wink

I'm not sure I dare to ask, but how many LED's is in that display ?

logjam · Joined: 15 May 2007 Posts: 14

19,008. It is 192x99, or 24x9 characters of 8x11 pixels.

I thought I'd be able to refresh 30 rows when I made the boards. I did some tests with my LEDs and found that I could only do a little over 10. I decided to refresh 11 rows at once since that is how many rows are in one character. The display will be refreshed as 1728x11.

I'm thinking about a different display of about 64x48. This display would display greyscale data. I took some movies I had and converted them to 64x48 greyscale. You have to squint to see them, but it was pretty good!

64x48 greyscale is 3072 bytes per frame. 4 bits of gray scale might be enough, so we could get 1536 bytes per frame.

It would be fun to use the Apple 1 as a source for the streaming video. Smile

It would take 15-30k per second so the 6502 would have no time to do anything but receive frames...

fsafstrom · Joined: 26 Dec 2006 Posts: 155 Location: San Antonio, Texas

Very impressive...

What kind of hardware do you use to drive the LED's ?
The MAX7219 "only" handles 8x8 LED's so my guess would be some kind of custom hardware...

By the way, I calculated my power requirement to be 3 Amps for the 575 LED's with full intensity.
For 19008 LED's that would translate into 100 Amps for the whole board... Wink

On the other hand, I never measured the actual consumption so I could be way off...

logjam · Joined: 15 May 2007 Posts: 14

Not off... Smile

I found a 5V 90A power supply here:
http://www.surpluscenter.com/item.asp?UID=2007051702510729&item=15-1050&catname=electric

There is also a new 5v 100A or even 150A supply for $168 or $295

http://www.power-factor-1st.com/shop/enclosed-switching-power-supplies/g2-series/page2.html

So it should be around as bright as a 500W light bulb all said and done... Which over the area of the entire panel shouldn't be TOO bright...

My driver circuits are here:

http://www.stockly.com/images2/060121-Root_1_1.PDF

Each DriverBlock.sch is one of these:

http://www.stockly.com/images2/060121-DriverBlock_1_1.PDF

I have not sketched out the design for the 11 row drivers. They are basically the same thing except I will be using MOSFETs instead of those ULN2803s.

I have a 574 latch so that the entire row of LEDs changes at once instead of seeing a possible "wipe" of the display as new line data is clocked in. Possibly a waste, possibly not. This display is not like yours. I have to actually multiplex the LEDs myself. The MAX chip does that for you. I'm probably going to use an FPGA to do all of the bit twiddling and then have the display appear to the computer as "memory". A bit in memory would show up as one LED. This also allows for interesting things like "seeing" a program run as its memory space changes! Smile

logjam · Joined: 15 May 2007 Posts: 14

That Root.sch I posted is for 64 columns. There are 1728 columns total. There are an estimated 8,000 solder joints in the driver boards. I am not looking forward to that.

fsafstrom · Joined: 26 Dec 2006 Posts: 155 Location: San Antonio, Texas

I saw that this thread passed 10 000 views, kewl...

Let's hope that at least one or two people got interested enough in the Replica to buy one... Cool