>  In this case I am writing the slave (on another
>PIC16F877), so I think I need to know the width.
>I want to make sure I can detect the pulse by polling,
>and send/receive the data before the next pulse.
>It looks like in order to do that, I need to set the
>master's clock rate high enough.

I think you will find that if you use the UART in synchronous mode, it will
act like a slave SPI interface. I have not done it, but this is the feeling
I get from discussion I have seen on this list about using the synchronous
mode. This will then save you trouble with making sure the master is slow
enough for the slave to keep up.

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