At 11:41 PM 1/21/03 +0100, you wrote:
>Hi.
>I'v been looking for the equivalent resistance
>of the "weak pull up" that can be enabled on some
>PIC types. There is a "weak pull up current" (param D070
>in the 18C ref manual), and from that is seems as
>the pull up could be between 12,5Kohm and 100Kohm.

It's more like a lousy current source than a lousy
resistor.

>What I'd like to do, is to connect the output
>of a opto coupler with transistor output without
>using an extra pull up resistor to 5v directly to
>a PIC pin.

The turn-off will be rather slow, of course. Be sure
to calculate and allow enough margin to account for
all the factors in the optos.

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

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