Lpc2000

----- Original Message ----- 
From: "Peter Jakacki" <peterjak@...>
To: <lpc2000@yahoogroups.com>
Sent: Sunday, April 10, 2005 9:49 PM
Subject: Re: [lpc2000] Re: port timing


>
> Update frequency is not the same as output frequency when toggling. If
> you turn the outputs on and off at an update rate of 7.4MHz you will end
> up with a output frequency of 3.7MHz.
>
> I run my 2106 at 22.1184MHz (overclocked) x3 and achieve an update
> frequency of ~8.3MHz or update period of 120ns on the GPIO pins. This is
> reading from RAM and writing shifted data. Toggling the pins would only
> give me a ~4.15MHz signal.
>
> Philips might wonder how important is I/O speed really, what's all the
> gripe about. I'd say it isn't important, -except- for embedded real-time
> control. Now which market did Philips intend these chips for?
>
> With the 2106 I generate 192x480x8 VGA graphics over 640x480 60Hz timing
> without any extra hardware other than some resistors. I really wish
> Philips would listen and improve the GPIO interface, how hard can it
> really be??? Surely it would have to be THE simplest fix.
>
> *Peter*
>

You are right, I did mean an update frequency.
Now, how can you generate video graphics with this frequency if pixel clock 
is 70nS (ntsc, and even less for pal) ?
That's about what I am trying to accomplish, and I am really lost.

Gennady