Lpc2000

----- Original Message ----- 
From: "embeddedjanitor" <manningc2@...>
To: <lpc2000@yahoogroups.com>
Sent: Sunday, April 10, 2005 3:12 PM
Subject: [lpc2000] Re: port timing


>
>
> --- In lpc2000@yahoogroups.com, "Gennady Palitsky" <gennadyp@j...>
> wrote:
>> Thanks a lot for the reference.
>> Too bad it's not documented anywhere in Philips' papers.
>
> I once asked Philps for a spec and they weasled out of it saying that
> there were too many variables.
> There are a few, including clock speed, MAM settings, VPB speed etc.
> The main problem is die to the way Philips attached the core to the
> GPIO. If they'd one it on the "fast bus" instead of the VPB things
> would be a lot faster.
>
> The Atmel SAM7 parts have much faster GPIOs but still not anyhere near
> single cycle.I prefer working with Philips than Atmel, but this one
> point was enough to make me choose an Atmel SAM7 part.
>

Unfortunately Atmel doesn't have IAP (the application engineer I spoke with 
sais they have it but don't advertise because it's not completed yet), and 
this is a requirement.


>>
>> So it seems that the BEST result I can get with loading consecutive
> data
>> from flash and storing at a port is 10 cycles...
>> (what with my 14.318MHz clock is ~230nS, actually a bit more then 3.
> 7MHz).
>
> That's about right.
>

BTW, when I use storing to port from registers (I can't use because of 
amount of data), I can get 7 cycles (scoped), what is above 6 Mhz for GPIO. 
Definitely above 3.7MHz... Why?


> The only way to get the data out fast with a Philps LPC21xx device is
> going to be using some sort of mechanism on the external memory bus.
>

Is external memory access faster then direct storing to GPIO?