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RE: RTC Trickle Charge Value



My problem is that I was using the 'date -s' command to set the time.  This says it works, but it does not work when I reset the devboard, for whatever reason.  I used 'hwtestrtc -s' and it works great.  Anybody know why?

Thanks,
Dave

-----Original Message-----
From: Johan.Adolfsson@xxxxxxx.com">mailto:Johan.Adolfsson@xxxxxxx.com]
Sent: Wednesday, July 02, 2003 9:47 AM
To: Dave Matlock; johan.adolfsson@xxxxxxx.com
Subject: Re: RTC Trickle Charge Value



----- Original Message -----
From: "Dave Matlock" <Dave.Matlock@xxxxxxx.com>
To: <johana@xxxxxxx.com>
Sent: den 2 juli 2003 17:08
Subject: RE: RTC Trickle Charge Value


> Johan,
>
> I guess I don't understand.  Are you saying the DevBoard82 cannot
> use the trickle charger, thus the RTC cannot keep time between power
cycles?

No, the devboard 82 has a battery mounted so you don't need to do
anything with the trickle charger to make it work.
Just use hwtestrtc or some other utility to set the RTC and you
should be fine.

> If I need this functionality, do I need to add the diodes and resistors
that
> you are mentioning?

No, the diodes and resistors are built into the DS1302 and there
is a register setting in the DS1302 that configures how they should be
connected to give the proper maximum charge current.
On the devboard_82 it is a non-rechargable battery so the trickle charger
shouldn't be used at all.
On the devboard_lx it is a capacitor so enabling the tricklecharger is
needed to keep time between power cycles.
(although the capacitor can be replaced with a battery -
 the PCB is prepared for that)

> Thanks,
> Dave

/Johan



> -----Original Message-----
> From: Johan.Adolfsson@xxxxxxx.com">mailto:Johan.Adolfsson@xxxxxxx.com]
> Sent: Wednesday, July 02, 2003 12:22 AM
> To: Dave Matlock; dev-etrax@xxxxxxx.com
> Subject: Re: RTC Trickle Charge Value
>
>
>
> ----- Original Message -----
> From: "Dave Matlock" <Dave.Matlock@xxxxxxx.com>
> To: <dev-etrax@xxxxxxx.com>
> Sent: Wednesday, July 02, 2003 1:32 AM
> Subject: RTC Trickle Charge Value
>
>
> > What value should I use for the DS1302 RTC chip trickle charge in the
> kernel configuration?  Is only one of the values valid or do they each
have
> different functions?
> >
> > Thanks,
> > Dave
>
> It depends on if the backup power source to the DS1302 is rechargable or
not
> and the maximum charge current for it.
> If it's not rechargable use 0.
> If it is rechargable you can choose to have 1 or 2 diodes and
> 2k, 4k or 8k ohm resistor to reduce the charge current.
>
> On a devboard_lx (with capacitor) I suggest: 6
> Imax = (3.3v-0.7V)/4kohm = 0.65mA
> (changing to 5 giving Imax = (3.3v-0.7V)/2kohm = 1.3mA
>  would probably be ok to)
>
> On a devboard_82 (with non-rechargable battery): 0
>
> /Johan
>
>