Lpc2000

John,

as Robert already mentioned your test includes the delays that are by
design in the path to the I/O pads if the I/O is connected to the APB
(Philips calls it VPB, same thing). You do not just measure execution
speed of code / instructions. 
Please use a program, lets say >> 1kB, look at the size and the
executed code and the average 1.9 should be very close to what you
will see. This number, 1.9,  is actually from ARM presentations I saw
at the ARM Developers Forum.

Bob

--- In lpc2000@yahoogroups.com, Robert Adsett <subscriptions@a...> wrote:
> At 10:21 PM 3/17/05 +0000, johnsonnenberg99 wrote:
> >I'm seeing slightly different numbers.
> >Yesterday I put two lines of code in my C program.
> >Line 1 was  IOSET0 = xxxx   to set an IO pin.
> >Line 2 wss  IOCLR0 = xxxx   to clear the same pin.,
> >This compiled to a total of 8 lines of assemble code using IAR.
> >When executed, the IO pin stayed high for 2 uS with a 24MHz clock.
> >This implies the 8 instruction took over 48 clock ticks.  I was in
> >the THUMB mode, and I'll try it again in the ARM mode.
> 
> I believe you are timing I/O speed not instruction speed.  Take a
search 
> back through the history of the group.  In particular there was some 
> discussion on this in the first month or two of the groups existence.
> 
> Robert
> 
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