Depends on the LED's ... most of the small 3mm, 5mm or 2x5mm rectangular =
ones=20
I use require 20-25mA, and PIC's can deliver 25mA.  However, I've found t=
hat=20
for normal indoor viewing, I get excellent brightness at 11mA ... and tha=
t's=20
also multiplexed !

If you multiplex with 1/16 duty-cycle, I'd guess you'd need to push the f=
ull=20
25mA thru them, but I feel sure you'll find this more than enough if you =
use=20
the right LED's.  Just compare mcd's at the tested currents for the LED=20
options you have.

If you do need more current, look at the ULN2003-type drivers, or get som=
e=20
transistor drivers on the row lines (and the column lines).  Best test ..=
=2E=20
setup a quick "LED-blinky" program, but with 1/16 duty-cycle and see if i=
t's=20
bright enough for you.

Cheers,
-Neil.


On Wednesday 11 June 2003 20:02, Thomas N scribbled:
> Hi everyone,
>
> With 32 I/O from the 16F877, I think I can control a 16x16 LED matrix
> display.  Because of the limited current coming out from the I/O, I don=
't
> think a PIC can drive the LEDs directly.  Is there a driver IC or somet=
hing
> to drive the LEDs?  Is there a better way to do this?
>
> Thank you in advance!
>
> Thomas
>
>
> ---------------------------------
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