calandar chip? or rtc chip which does not allow setting of

[Mike]

Anybody know of a chip which permanently keeps track of month/day/year
without allowing a user to set it?

What I mean is something that is already preprogrammed, has its own
little battery built in, returns the current date when asked, and will
last for about 5 years?

Thanks,
Mike

 

bsd_mike@hotmail.com (Mike) wrote:

Anybody know of a chip which permanently keeps track of month/day/year
without allowing a user to set it?

What I mean is something that is already preprogrammed, has its own
little battery built in, returns the current date when asked, and will
last for about 5 years?

Well, it kinda depends on where you want to use it, but if the
software drivers for a particular device don't implement the "setting"
functions, then it's essentially read-only. Might be as simple as
removing the write line in hardware....

What do you want to connect this to? What are you trying to do?

--
William Smith
ComputerSmiths Consulting, Inc. www.compusmiths.com

 

[Gecke Rün]

"Mike" <bsd_mike@hotmail.com> wrote in message
news:b2809f59.0405240412.51dfdaca@posting.google.com...

Anybody know of a chip which permanently keeps track of month/day/year
without allowing a user to set it?

What I mean is something that is already preprogrammed, has its own
little battery built in, returns the current date when asked, and will
last for about 5 years?

Thanks,
Mike

Take a look at
http://e-www.motorola.com/files/timing_interconnect_access/doc/data_sheet/MPC9653A.pdf

 

[Tim Shoppa]

bsd_mike@hotmail.com (Mike) wrote in message news:<b2809f59.0405240412.51dfdaca@posting.google.com>...

Anybody know of a chip which permanently keeps track of month/day/year
without allowing a user to set it?

What I mean is something that is already preprogrammed, has its own
little battery built in, returns the current date when asked, and will
last for about 5 years?

There are a number of products out there...

1. Real-time clock chips with battery built-in. All of the ones I know
about can be set as well as read. Battery life is usually around or greater
than 5 years. Maybe you can set it and gouge out a pin necessary to set it?
Dallas Semiconductor is a big name, see e.g.

http://www.maxim-ic.com/products/timers/real_time_clocks.cfm

2. Runtime meters. Often found on industrial equipment. These usually
only run when power is applied, but do not forget the accumulated time when
power is removed. Older ones are electromechanical, newer ones are digital.

3. Various electrochemical and/or radioactive processes used for timing.
Usually the electrochemical ones are temperature-sensitive (sometimes
extremely so).

"Already preprogrammed" is an interesting concept... what do you do
about the timezone? Most cheap quartz-based timebases are only good to
a few minutes a year... and under really adverse temperature extremes they
could be off by much more than that. Then there are TCXO's. Then there are
WWVB clocks. Then there are GPS receivers. Then there are Rubidium
standards...

Tim.

 

[Franc Zabkar]

On 24 May 2004 05:12:54 -0700, bsd_mike@hotmail.com (Mike) put finger
to keyboard and composed:

Anybody know of a chip which permanently keeps track of month/day/year
without allowing a user to set it?

What I mean is something that is already preprogrammed, has its own
little battery built in, returns the current date when asked, and will
last for about 5 years?

Thanks,
Mike

How do you account for daylight saving? What kind of inaccuracy can
you tolerate over five years?


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.