Back in the good ol' days of TTL, we had fan-in and fan-out
specifications. Now, the current requirements of a CMOS input are
extremely low, and the PIC can source or sink 25mA (when operating at 5V).
The limitations now are on how long it takes to get the line up to 5V or
down to 0V while driving several chips. I don't think you'll have any
problem driving 32 chips. If you have any trouble, it may just require the
addition of a nop in your code to let the data lines settle before sending
your strobe pulse.

Good luck!

Harold


>
> Hi to all engineers and happy new year.
>
> I have to drive 128 small motor thru small bridge driver. each motor needs
> 2 wires and I only have 8 pins available. all I have to do is select the
> motor
> and update the direction. I plane to use 74hc373 that it can latch while
> I am selecting different pair. In this case I am going to need 32 latches
> connected to the PIC 8 pin bus and thru chip select update the status.
> My question is can I connect 32 logic directly to pic port or I
> may need to connect thru buffer.
> sorry I forgot to mention that I have keypad and lcd connected to other
> ports.
> I am using 18F4520
> any idea or recommendation will appreciate.
>
> Andre
>
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