Lpc2000

Hi Arturo,

your measurement seems very much in line with what ARM is quoting for
the ARM7 core. The core can run in the average over all programs they
tested with 1.9 clocks per instruction. This is not LPC2000 specific,
rather ARM7 core specific. As side information, the ARM9 core is
quoted at 1.3 clocks / instruction, so inherently faster while running
at the same frequency. 

Now to the possible difference between the chips you might be testing.
A device running 0 wait states will be very close to what you
measured. If you would use for example external flash memory (or
internal) and have to insert wait states, you will see this factor
degrading depending on the number of wait states.

Another topic you would want to consider is whether you execute ARM
code or Thumb code. You will execute the same number of ARM or Thumb
instructions during a given time on the LPC2000 but you might find
that other devices with narrower busses will give you more
instructions in Thumb mode than in ARM mode. What does this mean?
Thumb mode has the benefit of reducing your code size by approx. 30
percent, or in numbers, 7 Thumb instructions replace 5 ARM instructions. 

It takes approx 10 clock cycles to execute the 5 ARM instructions on a
LPC2000 but it takes almost 14 cycles to execute the Thumb
instructions performing the same task. 

Your question if related to performance could then be rephrased to how
many clock cycles to perform a task in ARM and Thumb mode and now we
are exactly there what a benchmark is.  It is not as easy as how many
clock cycles per instruction but more how much time to perform a given
task with lots of parameters if comparing different devices. 

Accept my apologies for this lengthy e-mail but I could not resist ;-)

Cheers, Bob


--- In lpc2000@yahoogroups.com, "arturo tramontini" <a.t@t...> wrote:
> 
> someone know how many oscillator clock x instruction cycle?
> from my measure it's seems about 4 oscillator clock x instruction.
> thank's to all