Lpc2000

I believe I've set the PLL of an lpc2106 with a 14.7 mhz crystal up 
to be 59 Mhz

However when I toggle a GPIO pin using IOSET,IOCLR,IOSET it is only 
low for approx 200 nS. I was expecting quicker than this.

Any thoughts ???

Douglas
  Two things to remember.
1) It will take more than two assembly instructions to toggle
an IO line in a loop.  Take a look at the assembly code produced
by the compiler to determine the instruction count.
2) the GPIO is on the VPB (VLSI Periphereal Bus) and can only be
written at the PCLK rate.  If your PCLK divider is '1' then the
processor will not have to wait.  If not '1' then the GPIO pin
cannot be updated at the CLK (~59MHz) rate.

Regards
-Bill Knight
the ARM Patch


On Wed, 05 May 2004 10:24:17 -0000, douglasbolton wrote:

I believe I've set the PLL of an lpc2106 with a 14.7 mhz crystal up 
to be 59 Mhz

However when I toggle a GPIO pin using IOSET,IOCLR,IOSET it is only 
low for approx 200 nS. I was expecting quicker than this.

Any thoughts ???

--- In lpc2000@yahoogroups.com, "douglasbolton" <doug@c...> wrote:
> I believe I've set the PLL of an lpc2106 with a 14.7 mhz crystal up 
> to be 59 Mhz
> 
> However when I toggle a GPIO pin using IOSET,IOCLR,IOSET it is only 
> low for approx 200 nS. I was expecting quicker than this.
> 
> Any thoughts ???

where do you run your code from? RAM or Flash?
Flash can't work at 59Mhz (read the docs ;) and usually code from 
Flash runs slower than from RAM - make blink LED code and compile it 
for RAM and Flash - you will see visual the difference

Best regards
Tsvetan
---
PCB prototypes for $26 at http://run.to/pcb 
(http://www.olimex.com/pcb)
PCB any volume assembly (http://www.olimex.com/pcb/protoa.html)
Development boards for ARM, AVR, PIC, and MSP430  
(http://www.olimex.com/dev)

At 10:24 AM 5/5/04 +0000, you wrote:
>I believe I've set the PLL of an lpc2106 with a 14.7 mhz crystal up
>to be 59 Mhz
>
>However when I toggle a GPIO pin using IOSET,IOCLR,IOSET it is only
>low for approx 200 nS. I was expecting quicker than this.
>
>Any thoughts ???

See http://groups.yahoo.com/group/lpc2000/message/37 the thread where this 
was discussed earlier.

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

tsvetanusunov wrote:
> where do you run your code from? RAM or Flash?
> Flash can't work at 59Mhz (read the docs ;) and usually code from 
> Flash runs slower than from RAM - make blink LED code and compile it 
> for RAM and Flash - you will see visual the difference

True, but if you have the memory accelerator (MAM) on, this tight of a 
loop should run with zero wait states from flash on the 21xx.  A loop 
this small will probably fit completely in the MAM buffers.

Ryan