Lpc2000

As far as I can tell SPI clocks tend to be more expensive. Are you  
using the I2C pins for GPIO? If not, why must it be SPI?

Things to get cheaper if you don't need the alarm (but then you must  
have some other external interrupt source to wake the cpu up). For  
example, STMicro's M41T0 is $1.80 quantity 1 ($0.81/1k) from Digikey.  
Probably cheaper elsewhere. As far as I can tell the Dallas chips are  
more expensive.

It is unfortunate Philips didn't put the RTC on it's own clock...

Shannon

On May 15, 2004, at 8:26 AM, Milos Prokic wrote:

> Thanks!
>
> The thing is that the price is really an issue, in addition all of the  
> other peripherals are controlled through SPI bus, so if it is an  
> external chip it has to be SPI. How about Dallas chips? Any  
> experience?
>
>  It’s a pain.. cause buying something that’s already on the chip seems  
> like a waste of money…  if it’s not too crazy on power, I might be  
> able to go with the internal one...
>
>  Cheers,
>
> m.
>
>  
>
>  
>
>
> From: Bill Knight [mailto:BillK@...]
>  Sent: Saturday, May 15, 2004 9:34 AM
> To: lpc2000@yahoogroups.com
> Subject: RE: [lpc2000] Re: LPC210x RTC
>
>  
>
> Try using an external STMicro M41T81 RTC.  It interfaces via the I2C  
> bus
> and has a multi-function pin (watchdog reset, alarm interrupt, etc.)
> It also has a register for calibrating the crystal.  Reasonably low  
> cost
> and available from Digikey for $2.40 USD.  Then set the RTC to wake up  
> the
> ARM via an external interrupt and put the LPC to sleep.
>
> Regards
> -Bill Knight
> theARMPatch
>
>
>
>
> On Sat, 15 May 2004 03:43:27 -0400, Milos Prokic wrote:
>
> Hi, thanks on your reply.
>
> Since the RTC is essential for my application, as well as low cost and  
> low
> power consumption I was wondering if you know how much power is  
> required to
> keep the RTC running? Is that a good approach? If you know  
> approximately
> what is the average current consumption if all the peripherals are  
> switched
> off except for RTC and the chip is placed in the idle state that would
> really be of great help.
>
> Thanks in advance,
>
> Milos
>
>
>
>   _____ 
>
> From: philips_apps [mailto:philips_apps@...]
>  Sent: Tuesday, May 11, 2004 3:02 PM
> To: lpc2000@yahoogroups.com
> Subject: [lpc2000] Re: LPC210x RTC
>
>
>
> Hello Milos,
>
> The RTC cannot work once the microcontroller enters the power-down
>  mode, since there will be no clock supplied through the
> microcontroller and consequently to the RTC block. The only low power
> mode that the RTC user can utilize is the idle mode.
>
> Regards,
>
>
> --- In lpc2000@yahoogroups.com, "Milos Prokic" <milos.prokic@m...>
>  wrote:
> > Hi everyone,
> >
> > I was wondering if anyone has made use of the RTC module.
> >
> > I'm not quite clear from the documentation if the RTC can be used
> during
> > powerdown. The doc says that there will be lapse in the time
> update. I'm not
> > sure if they mean that this "lapse" results from altering the
> prescaler
> > values so that it can get the feed from frequency oscillator and
> not the PLL
> > or that it will just stop working until you bring it back from
> power down?
> >
> > Thanks a lot,
> >
> > m.
>
>
>
>
>
>
> Yahoo! Groups Sponsor
>
>
>
> ADVERTISEMENT
>
> <http://rd.yahoo.com/SIG=129v66efi/M=295196.4901138.6071305.3001176/ 
> D=groups
> /S=1706554205:HM/EXP=1084388542/A=2128215/R=0/SIG=10se96mf6/*http:/ 
> companion
> .yahoo.com> click here
>
>
>
> <http://us.adserver.yahoo.com/l?M=295196.4901138.6071305.3001176/ 
> D=groups/S=
> :HM/A=2128215/rand=776698535>
>
>
>
>    _____ 
>
> Yahoo! Groups Links
>
> *      To visit your group on the web, go to:
> http://groups.yahoo.com/group/lpc2000/
>  
> *      To unsubscribe from this group, send an email to:
> lpc2000-unsubscribe@yahoogroups.com
> <mailto:lpc2000-unsubscribe@yahoogroups.com?subject=Unsubscribe>
>   
> *      Your use of Yahoo! Groups is subject to the Yahoo!
> <http://docs.yahoo.com/info/terms/>  Terms of Service.
>
>
>
>
>
>
>
>
>
>
>
> Yahoo! Groups Sponsor
>
> ADVERTISEMENT
> <image.tiff>
> <image.tiff>
>
> Yahoo! Groups Links
>
> 	• 	To visit your group on the web, go to:
> http://groups.yahoo.com/group/lpc2000/
>  
> 	• 	 To unsubscribe from this group, send an email to:
> lpc2000-unsubscribe@yahoogroups.com
>  
> 	• 	 Your use of Yahoo! Groups is subject to the Yahoo! Terms of  
> Service.
>
>