Tetris on a PIC

[MrDEB]

Been planning this for awhile and a recent post over at DDIY about board size is impossible using the 38mmx38mm LED matrix as I assume they are referring to. 38 * 2 = 76mm plus the switches which are 12mm across 76 + 24 = 100 but no room for space in between as I see it.
Have been working on a board but using SMT for all except the LED matrixs. Looking for right size so entire project can fit on a very small board from Itead studios.
http://digital-diy.com/forum/electronic ... tml#p14671
anyone who wishes to get involved with this is welcome.

[W4GNS]

I'm curious, as I'm THE KING of fat fingers. How small do you think this board can go, and still be practible ? I understand making it small cost wise, but looking at the picture it already appears to be small considering it's a game to play, press buttons, etc. If it was an occasional button press I can see smaller. But the main point of the game is pressing buttons, and small would be more difficult,for me anyway.

[brad]

How about you mix it up a bit and put in an accelerometer. That way you can move the pieces around by tilting

Speaking of small designs - I should be receiving my latest order from itead studio. These boards are the same size as the bi-color led matrix displays (32mm x 32mm) It's something I plan on selling real soon now!

screen-capture-24.png (51.06 KiB) Viewed 18115 times

screen-capture-23.png (53.19 KiB) Viewed 18115 times

The board holds:
18f43k20 microcontroller
mini usb socket
lithium polymer battery charger chip
2 x capacitors
push button
on / off switch
8 x 2n2222 transistors
27 x resistors
2 x photodiodes
bi-color led matrix

[MrDEB]

Curious about your Itead boards?
Exactly what does it do with only one 32 x 32 display.
This is very similar to a project I started, got sidetracked and now back to it.
A schematic and/or description of this upcoming project.

[MrDEB]

After retiring to bed I got to wondering why you used transistors instead of say a ULN2803? I redid my Tetris board design using individual 1206 resistors instead of 16pin smd resistor paks. Layout looks cleaner but more components.
THANKS to Jon for changing coarse instead of moving switches around and suggesting rotating the board 45 degrees, the board can then be 100mm x 100mm.
If I used smaller LED matrix blocks I think could make this fit on a 50 x 50 board and fit in ones pocket. The switches are then a real issue but then look at how small a cellphone has switches.

[MrDEB]

transistors w/ bias resistors built in!!
http://www.mouser.com/ProductDetail/NXP ... 0RPw%3d%3d
never heard of this but might be easier to use than the ULN2803 as I am having issues with traces.

[brad]

Nice find with those transistors! that would save a lot of extra soldering (not to mention space on your PCB)

I used transistors instead of the ULN2803 because the LED matrix is a common anode variety. If they were common cathode then the ULN2803 would be perfect

[MrDEB]

planning on using http://www.mouser.com/ProductDetail/Pan ... NAKhw6c%3d
has a 2.2k resistors.
Laying out the board using a uln2803 gets impossible.

[MrDEB]

It shouldn't make to much of a difference common Anode or common Cathode. The uln2803 could be used for either I would think. Just change the output level.

[bitfogav]

It shouldn't make to much of a difference common Anode or common Cathode. The uln2803 could be used for either I would think. Just change the output level.

The UNL2803 uses eight NPN Darlington transistors?!

[brad]

It shouldn't make to much of a difference common Anode or common Cathode. The uln2803 could be used for either I would think. Just change the output level.

What do you mean exactly?

[MrDEB]

I was thinking out loud that maybe a ULN2803 could be used as a "high side" switch by using a pull down resistor or ?.
Perhaps have the PIC output a high then go low for switching or ???

[brad]

Unfortunately not. It was a bit annoying actually because I originally designed my circuit with a ULN2803 and didn't realise that it wouldn't work until it was basically complete!

[MrDEB]

Talk about annoying, I realized that I designed my present schematic using a common anode instead of common cathode matrix. My latest project I have some help from Kingbright concerning matrix block size etc. Working on getting a sample of 8 x 8 Led matrix w/ 10mm LED dots in RED and Green if they even have such a beast.
Received samples of 5 x 7 bi color matrices.
To add to my problems when I printed the board design to copper I failed to disable the silk screen layer. Spent time scratching away unwanted black lines on one side. Tomorrow after I print the bottom layer, back to scratching.
Back to it tomorrow is the best solution to avoid going from bad to worse.

[brad]

Scratching copper off is no fun, can you post a pic of how the board turned out?