>Hello all. Was wondering about something. I've been trying out this
>Zilog starter kit that I got as part of entering the Circuit Cellar
>contest.
>
>The module has a Zilog eZ80F91 part on it with a 50MHz crystal. I've
>been scouring the datasheet to answer one silly question: what
>instruction rate does 50MHz system clock get me? I know not all the
>instructions are single cycle.
>
>The reason I ask is I have a program (in C) that wiggles a pin up and
>down, and when I put a scope on it it's frequency is only about
>50kHz!!??? Am I doing something wrong or is the MCU REALLY that
>inefficient? Does the chip come up is some "slow" default mode or
>something?
>
>Currently I'm changing the GPIO bit with stuff like this:
>
>PB_DR &= 0x7f;
>PB_DR |= 0x80;
>
>Is there a better way? I've tried stuff like PB_DR[7] but none of it
>works.

Herb, I did this several months ago on my dev kit using assembler and it
produced way way over 50kHz.  I'll try and setup the dev board on my bench
this week and give you an exact number.

Regards
Jean-Michel.

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