newbie Q - edge detection?

[RMCRAVEN]

Hello

I'm looking through the PB Pro manual, trying to work out how to detect a rising edge on a port input (for a PIC such as a 16F628, for example).

I want to detect edges rather than levels - rising and falling - on inputs and generate output pulses which occur as a result. The inputs will be (0V-->+5V) or (+5V-->0V) transitions, derived from TTL or CMOS input pulses or clocks etc.

By the way, I realise that there'll be some propagation delay through the PIC due to machine cycles etc. but that's not a problem - a few us in a few tens of ms is a small per cent delay. I should also note that I realise that I can differentiate the input with hardware in order to provide a narrow pulse and measure it with PULSEIN etc - I want to see if it can all be done in firmware though.

Can anyone suggest how to build a routine in PBPro? I can't see from the commands in front of me how to go about it (I am assured it is possible in ASM but that's a bit ambitious for me at the moment).

Cheers for any pointers - I'm having fun at the moment downloading example .BAS files and compiling them to the hex and ASM results, in an atttempt to relate the assembler listing to the basic source.

RMC, England