[vdr] Re: OT: LED circuit

[Christian Berger <einStein@donau.de>]

Am Montag, 12. August 2002 14:48 schrieben Sie:
> Hi!
>
> Sorry for beeing off topic.
> Does anybody know a circuit design for accessing a 2 1/2 digit 7-segment
> LED display via serial or parallel port?
> The serial dot matrix displays are to expensive for me and I want to use
> LED display which already exists in my case (was used to show the cpu
> clock frequency) to display eg. the channel number. Using the harddisk
> activity indicator LED as "recording" indicator also would be a nice
> idea. Thanks!!!

Hmm, well it should be possible to do something like that with shift 
registers. This is relatively expensive since a 
shift register is about 50 cents. (there are also dual shift registers 
avaliable).

I would use the strobe signal of the parallel port as clock signal of the 
registers. They would have to be serial in and parallel out. For each 
digit you have a shift register. The digit's LEDs are connected to the 
parallel output of the register. The serial data-in is connected to one of 
the data-out lines. Since we have 8 data-lines you could connect up to 8 
digits. (even more if you change it a bit)

What do you think?

> Christoph

Servus
  Casandro
-- 
#define T 1000
#define M T*T
int main(){int x,y;for(y=0;y<20;y++){for(x=0;x<70;x++){int
c=-1;int xr,yr,zr;int xp,yp,zp;xp=yp=zp=0;xr=(x-35);yr=(y-
10);zr=10;while(1){if(yp>T){c=5;if((((zp)/T)%2==1)^(((xp+M
)/T)%2==1))c=0;break;}if(zp>T*10){c=0;if (((yp*yp+xp*xp)/(
T*100))%2==1)c=2;break;}zp+=zr;xp+=xr;yp+=yr;}printf("%c",
c+32);}printf("\n");}};