Lpc2000

> This means that the contents of the clock are a bit fragile, really -
> suggesting it will be better used as a local 'cache' of an external
> seperately-clocked real time clock unit that's slow to access (I2C or
> similar), loaded from it during startup or return from power down mode
> after setting up the PLL and the RTC divider registers. Unless you have
> a setup that's rarely reset and never put into power down mode, it's not
> all that useful, as I see it.

I have this low power design that I'm working on and I'm using PCF8593 I2C
RTC with 32.768kHz clock. PCF will take only 1uA so I planned to put MCU in
Power Down most of the time. When running, MCU will take time and date from
PCF and use it with its own integrated RTC just as you suggested. PCF will
be updated only when time or date is changed by user.

> Anyone else had any thoughts about it? It would have been nice if they
> provided an external 32,768Hz clock input pin to run the RTC off of when
> the MHz oscillator was down!

Looking at LPC spec for the first time that's what I expected. Later,
looking at User Manual was very... well... disappointing. Who needs RTC with
20mA current consumption (when in Idle mode)?????

> On the other hand, it occurs to me that the PLL seems amply capable of
> producing processor clock frequencies far in advance of the rated 60MHz
> - overclocking! How soon before we see huge copper heatsinks with fans
> for LPC2100s, eh? ;-)

Few days ago someone said that they used overclocked LPC without any
problems...

Regards,
Igor