Hi Tom=E1s,
you can save some pin by using a HC589 8 bit input shift register and =

driving it with only 3 pins.
- check the pin numbering for the pic: vpp/re3 is number 1 not 13 (maybe =

there are more wrong).
- the HC595 can be cascaded so you can have 8*5 =3D 40 output with only 3 p=
in
Cheers
      Nicola



Tom=E1s =D3 h=C9ilidhe wrote:
> I'm making an electronic portable Connect4 game that will run on =

> batteries. It started out as a project for college but now I'm just =

> doing it over the Summer for fun.
>
> The game consists of a matrix of bi-colour LED's which represent the =

> chip places:
>
>     x   x   x   x   x   x   x
>     x   x   x   x   x   x   x
>     x   x   x   x   x   x   x
>     x   x   x   x   x   x   x
>     x   x   x   x   x   x   x
>     x   x   x   x   x   x   x
>
> The display is multiplexed, only one column is ever lit at a time. In =

> each column, all the LED cathodes are common, and the common cathode =

> goes to a low-side driver which is controlled by a PIC pin.
>
> Under each column there's a push button. You press the push button and a =

> chip falls into that column. Player 1 has green chips, Player 2 has red.
>
> I've decided to use the three-pin LED's that are called "tri-colour", =

> but I'll only be using them as bi-colour (i.e. I won't ever have both =

> colours lit at the same time).
>
> I'm using the PIC16F887 this time around (the 40-pin DIP kind) and I'm =

> using the Pickit2 to program it.
>
> The 887 has 5 ports: A, B, C, D, E
>
> Port B is the one that has internal pull-up's so I think it's the =

> natural choice for the push buttons. I'll have 7 push buttons but =

> unfortunately I can only use 5 pins on Port B because I need RB6 and RB7 =

> for hooking up to the Pickit2 (my board is going to have a header for =

> hooking up the Pickit2). For the final push button, I use the RE3 pin in =

> conjunction with my own pull-up resistor.
>
> For driving the rows, I opted for port D because it's pretty much just =

> an I/O port. I needed more pins for driving the rows so I used A0 thru =

> A5 also.
>
> For driving the columns, I opted for port C.
>
> Port E is the "save the day" port that just cleans up the mess of not =

> being able to use other pins such a RB6 and RB7.
>
> Here's a link to the current schematic of my project, I'd appreciate if
> you'd take a look and see what you think, give me advice! :-D
>
> http://users.imagine.ie/toe/scoth.pdf
>
>
>
>
>   =


-- =

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