RTC for MPC8xx with Linux ?

RTC for MPC8xx with Linux ?

[David Jander]

Hi everybody,

Thanks for all the answers I got over experience with the MPC852T.
One other thing I was investigating is the RTC.
What RTC solutionts are known for easy interfacing with MPC8xx processors,
that work under linux ? What's the standard ?
There are a number of PC-compatible RTC chips out there, but I don't seem to
like them much, because they're generally quite expensive, have a lot of
functionality which might be nice, but is not really needed in my case.
Any experience with smaller 1-bit (or SPI) RTC's under linux ? I'm looking
basically for a Battery-backuped time-keeping counter.

Greetings,

--
David Jander
Protonic Holland.


** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

RE: RTC for MPC8xx with Linux ?

[Cedric Aubert]

Hi

Personnaly I use a DS1306 on SPI to do RTC on a
MPC860.
I don't use it under linux still now. But succesfully
run it under RTOS.

It's port under U-Boot so it's should not be difficult
to
use it under linux. If someone have some more
information
about DS1306 under linux (or throught U-Boot may be).

If you want to look at the DS1306 U-Boot driver, look
at
		boot/u-boot/rtc/ds1306.c

Expects that help

Cedric

> -----Original Message-----
> From: owner-linuxppc-embedded@lists.linuxppc.org
>
[mailto:owner-linuxppc-embedded@lists.linuxppc.org]On
Behalf Of David
> Jander
> Sent: Thursday, June 19, 2003 3:37 PM
> To: linuxppc-embedded@lists.linuxppc.org
> Subject: RTC for MPC8xx with Linux ?
>
>
>
> Hi everybody,
>
> Thanks for all the answers I got over experience
with the MPC852T.
> One other thing I was investigating is the RTC.
> What RTC solutionts are known for easy interfacing
with MPC8xx processors,
> that work under linux ? What's the standard ?
> There are a number of PC-compatible RTC chips out
there, but I
> don't seem to
> like them much, because they're generally quite
expensive, have a lot of
> functionality which might be nice, but is not really
needed in my case.
> Any experience with smaller 1-bit (or SPI) RTC's
under linux ? I'm looking
> basically for a Battery-backuped time-keeping
counter.
>
> Greetings,
>
> --
> David Jander
> Protonic Holland.
>
>


** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

Re: RTC for MPC8xx with Linux ?

[Wolfgang Denk]

Dear David,

in message <200306191537.28949.david.jander@protonic.nl> you wrote:
>
> Thanks for all the answers I got over experience with the MPC852T.
> One other thing I was investigating is the RTC.
> What RTC solutionts are known for easy interfacing with MPC8xx processors,
> that work under linux ? What's the standard ?

There is no standard. The choice  is  made  by  product  requirements
(price, accuracy, battery lifetime, etc). Then the driver is dapted -
which usually is pretty trivial.

> There are a number of PC-compatible RTC chips out there, but I don't seem to
> like them much, because they're generally quite expensive, have a lot of
> functionality which might be nice, but is not really needed in my case.
> Any experience with smaller 1-bit (or SPI) RTC's under linux ? I'm looking
> basically for a Battery-backuped time-keeping counter.

See the existing driver; for example, in our kernel  trees  you  will
find support for the PCF8563, M41T11, DS12887 and similar RTCs.o

This is not a big deal. Be careful though when running  NTP  on  your
system,  especially  when  using a RTC with I2C or SPI interface. You
will have to disable the  11  minute  mode  (see  "man  hwclock"  for
details).


Best regards,

Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
"It is better to have tried and failed than to have  failed  to  try,
but the result's the same."                           - Mike Dennison

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