gumstix

You could use something like DS1307 with a coin cell battery.
You can query it over I2C and get date time info.

   -- Doug


Tom Hansen wrote:
> 
> Has anyone implemented a hardware clock with the gumstix?
> 
> I'm looking at a remote data collection application where it is 
> important to record the time of measurement.

> Tom Hansen wrote:
> >
> > Has anyone implemented a hardware clock with the gumstix?
> >
> > I'm looking at a remote data collection application where it is
> > important to record the time of measurement.

I've never done it with the Gumstix platform, so I have no turnkey
solution. But here are three or four leads for clock HW that ought to
be use-able.

1) If you want something really tiny, here's a nice looking unit:
http://www.microcrystal.ch/products.aspx?CatalogID=3D1&CategoryID=3D3&Produ=
ctID=3D14&HasFlash=3Dtrue
...but I don't know how hard it'd be to get small quantities and you'd
need to rig the battery backup.

2) If you care to use a serial port you can try the "Pocket Watch B"
from Solutions Cubed. Depending on how you have your Gumstix rigged,
that might be the easiest option.
But make sure you're using the correct interface.

(I believe you want straight _logic levels_ from the PXA, NOT inverted
232 bipolar levels that come out of the gumstix mini-DIN; someone feel
free to correct me if I err):

http://www.parallax.com/detail.asp?product_id=3D27962
http://www.parallax.com/dl/docs/prod/comm/pocketwatchb.pdf
...and you still have to rig the extra battery up. Also, skim this
list's archives for info about recent serial port driver problems and
workarounds for same.

3a) This one uses I2C, is all set up including the Li cell, but it's
6x6 cm and wastes a lot of board space:
http://www.bipom.com/documents/peripherals/rtc.pdf

3b) The same folks make a version that does clock + MMC memory for
datalogging too, and that one uses the same size board more
effectively. The MMC I/O is probably on the slow side, but OTOH it
might suit you just fine, depending. Check their assortment of 6x6
boards at:
http://www.bipom.com/periph_boards.shtm

Cheerio!

--
      Michael M. Butler  :  m m b u t l e r  ( a t )  g m a i l . c o m
Churchill once said, "When you're going through hell, KEEP GOING".

OK, on reviewing the stuff I mentioned at greater length-- the Pocket
Watch B is what I'd try, and yes, it uses straight logic levels for
serial UART communications, and needs no handshaking. If I get around
to doing something with it myself, I'll post it to the Wiki.

It appears that the bipom.com MMC stuff is nontrivial to interface to
a Gumstix.  I'd stick with the native Gumstix SD hardware if it were
part of the HW I chose.

--
      Michael M. Butler  :  m m b u t l e r  ( a t )  g m a i l . c o m
Churchill once said, "When you're going through hell, KEEP GOING".

Sorry for the volume, but I just got off the phone with Solutions
Cubed. Their qty 1 price for the Pocket Watch B is now $22, which is a
much better deal than Parallax's price ($29?!). Go to the source, sez
I:

 http://www.solutions-cubed.com/solutions%20cubed/products2003.cfm .

I belive it only has one-second resolution, but you can probably poll
for the lsb transition if you want less logging jitter.

Now I need to get a life. Ahem.

--
      Michael M. Butler  :  m m b u t l e r  ( a t )  g m a i l . c o m
Churchill once said, "When you're going through hell, KEEP GOING".

exactly my problem too :-( which is why I have to keep using Applied 
Data's BitsyX
:-)
one day....
Kirk
At 21:05 28/10/2005, you wrote:

>Has anyone implemented a hardware clock with the gumstix?
>
>I'm looking at a remote data collection application where it is 
>important to record the time of measurement.  It is possible that 
>this remote sensing station will lose power occasionally.  I can of 
>course configure the gumstix to simply boot up and resume data 
>collection, but if it is unable to contact a time server, the time 
>clock will be incorrect.
>
>Thanks.
>
>
>
>
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-
http://www.ecs.soton.ac.uk/~km

On Fri, 2005-10-28 at 15:05 -0500, Tom Hansen wrote:
> Has anyone implemented a hardware clock with the gumstix?
> 
> I'm looking at a remote data collection application where it is 
> important to record the time of measurement.  It is possible that this 
> remote sensing station will lose power occasionally.  I can of course 
> configure the gumstix to simply boot up and resume data collection, but 
> if it is unable to contact a time server, the time clock will be incorrect.
> 
> Thanks.
> 

Hi Tom,

Might be worth looking at the following:
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4984

RTC with integrated TXCO, which communicates over I2C.

HTH,

Phil

On Thu, 2005-11-03 at 17:47 +0000, Philip Trickett (List) wrote:

> Hi Tom,
> 
> Might be worth looking at the following:
> http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4984
> 
> RTC with integrated TXCO, which communicates over I2C.
> 
> HTH,
> 
> Phil
> 


I forgot to say that they do samples on that page as well.

Phil