rtc battery for rev C3

Sean D'Epagnier

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May 30, 2009, 3:52:40 AM5/30/09

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Hi,

I noticed the new beagle has a space for an rtc battery. This is
great news, but I am not sure which way around to solder it in, so I
didn't yet. Then I noticed with an ohm meter that the two pins are
shorted together, and to ground is that correct?

Has anyone used the rtc battery? If so which way does it go?

Thanks,
Sean

Søren Steen Christensen

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May 30, 2009, 4:08:34 PM5/30/09

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> Then I noticed with an ohm meter that the two pins are
> shorted together, and to ground is that correct?
> Has anyone used the rtc battery? If so which way does it go?

Hi Sean,

I haven't seen the C3 schematics nor do I have a C3 board myself. The backup
battery is supposed to be connected between the BKBAT pin on TPS65950 and
GND. One pin is therefore OK being GND. The other one is connected
internally in TPS65950, and might therefore measure low impedance to GND as
well in case it's not enabled - To be honest I don't know.

In order to continue forward without knowing the polarity of the pins I
would recommend you to connect a 10-100uF non-polarized capacitor or
similar. Then start charging at the BKBAT pin and measure the polarity with
a voltmeter. You can then connect the right backup battery afterward...

Best regards - Good luck
Søren

Gerald Coley

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May 31, 2009, 7:37:34 PM5/31/09

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PLEASE wait until the System Reference Manual has been posted and you have read it before you make any attempt to put a battery in it. It is described in the SRM. Jason has the SRM, but has not as of yet updated the site with the information.

Any damage to the board as a result of improper installation of the battery is not covered under the warranty. In other words, you will be charged for any repairs.

Gerald

Gerald Coley

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Jun 1, 2009, 3:38:24 PM6/1/09

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The Rev C3 SRM is now available for download. It shows you how to install the RTC battery and the partnumber of the battery to be used.

Gerald

Philip Balister

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Sep 18, 2009, 10:52:31 AM9/18/09

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On Mon, Jun 1, 2009 at 3:38 PM, Gerald Coley <ger...@beagleboard.org> wrote:
> The Rev C3 SRM is now available for download. It shows you how to install
> the RTC battery and the partnumber of the battery to be used.

Has anyone installed the battery on the their Beagle? How well does it work?

Philip

Krishna Sagiraju

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Sep 21, 2009, 5:53:56 PM9/21/09

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I did, on my rev c3. Used "hwclock" to set the hardware time once and the time is well maintained so far (it been about 3 weeks).

--Krishna/.

Special Computing

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Sep 21, 2009, 6:35:55 PM9/21/09

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The Beagleboard design has a 7mAh secondary (rechargable) Venadium Pentoxide Lithium battery rather than a primary (non-rechargable) battery like on a PC motherboard.