In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Peter Van der Zee wrote:

Thanks Micheal and Paul;

I fully understand the operation of two cascaded flip-flops; but I still can't understand the significance/application of SYNC when it comes to the SX.

If an input was clocked (read) at a point of transition, the processor w register would see it as a one or a zero. On the other hand, had SYNC been enabled, then the first F/F would also read it as a one or a zero because it is synced to the same clock. And one more clock later it would be through the delay chain.

So in the UNSYNCED case, a READ would put the present data into W, and in the SYNCED case it would put the value at the input two clocks ago into W.

In both cases, if the clock uccurred at the transition point of the input, the result would be uncertain; for UNSYNCED it is uncertain NOW, and for SYNCED it is equally uncertain two cycles LATER. The uncertainty is just delayed.

I don't get the usefulness of this........ but wondered what I was missing.

Cheers,

Peter (pjv)

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