Lpc2000

At 08:42 PM 10/6/04 +0000, you wrote:
>This is my first ARM project so please excuse me if this is a dumb
>question.
>I have an application where I need maximum GPIO speed.  The
>datasheet mentions that a VPB divider greater than 1 is needed at
>max processor clock speeds but I cannot find what that speed is.
>What is the max clock speed for the VPB (GPIO) bus?

Not a dumb question, it's not documented anywhere (at least I've not seen 
it).  A VPB of 1 appears to work with no problem up to 60MHz.  I suspect 
that the VPB is in there primarily for two reasons right now, 1- by 
reducing the peripheral clock speed you can reduce the power consumption of 
the peripherals and 2- if/when they go to a higher max speed they can 
document a lower max for the VPB and the HW already exists.  There is an 
interesting note in the RTC section that talks about higher envisioned bus 
speeds.

Robert

" 'Freedom' has no meaning of itself.  There are always restrictions,
be they legal, genetic, or physical.  If you don't believe me, try to
chew a radio signal. "

                         Kelvin Throop, III