At 07:40 PM 5/19/02 -0500, you wrote:
>Just started looking thru my bin of old TTL parts for a 74xx244 or some
>other driver to experiment with driving a higher current thru my 4 mux'ed
>LED's.  But then I thought -- if I have extra ports on the PIC, why can't
>I run these in pairs for each LED segment?  At 25mA max source/sink
>on a 16F872, I could get 50mA to the LED's.  And to prevent the
>condition of 2 pins of a pair being out of sync, I would use 2 pins on the
>same port for each LED ... RB0 and RB1 for segment a, RB2 and RB3
>for segment b, etc.

Yes, you could do that.. But I'd suggest getting a brighter display,
port pins are generally too valuable to waste 8 of them (the driver
would be cheaper). There is some worry about what could happen if the
port (through noise or whatever) gets set so the outputs are fighting
each other, but you'll be updating the port every few milliseconds
anyway.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
9/11 United we Stand

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