Lpc2000

On Thu, 05 Feb 2004 00:19:53 -0000, lpc2100_fan wrote:


Hi,

I wondered as well why there was no 32 kHz input for the LPC. This
question was also asked at the Philips training that I participated.
The answer was along the lines of "there are applications that are
always connected to AC and they need to track time" well I guess that
is true. "Also the are other applications that need to go into power
down for minimum power and still should track time with some uAs of
power. Unfortunately this can not be done with the current
implementation of the LPC."  Guess that is true as well. The proposed
solution was to use a small LPC900 device, e.g. an 8-pin micro that
would have a RTC / System Clock. Looked into this a little and it can
definitely be done. Providing 32 kHz to such an LPC900 device and
using the 1k Flash to generate a real time-of-day timer is not hard to
do. According to my information the LPC900 devices would be lower cost
 than the PCF 8593 and more flexible but on the downside it would
require some 10s of uAs instead of 1 uA. If battery driven that can
make all the difference.

You may come up with your own conclusions ;-)

======================================================================
Interesting comments Bob.  You got me thinking.  I've got a board in
fab that uses a X1226 RTC because I didn't feel the LPC's RTC would
do the job I needed.  The cost from Digikey is $4.09 and it's back-ordered.
One the next turn of the board I may replace it with a MSP430F1101 which
is $2.48 from Digikey and is suppose to be in stock.  It will run directly
from the same battery and crystal as the 1226 part.  A bit-banged serial
interface should be no problem.

Regards
-Bill Knight
R O SoftWare