RE: question about ACPI & Smart Batteries

RE: question about ACPI & Smart Batteries

[Grover, Andrew]

> I am trying to understand the information flow between a 
> Smart Battery and the values
> I can see at /proc/acpi/battery/BAT0/state. I lookedt at ACPI 
> standard, and it says
> that if the battery supports "smart battery", it is 
> responsible by providing the battery
> related values (please correct me if I am wrong). Than I took 
> a look at "Smart Battery"
> data standard and it specifies the parameters. It also says 
> that this parameters should
> be polled by the SMBus Host.
> 
> What I really want to know is how often 
> /proc/acpi/battery/BAT0/state is updated when
> a battery is discharging/charging. 
> 
> I do not have acpid installed, and I running Debian kernel 
> 2.6.6, with acpi version
> 20040326. 

Unless you have a Fujitsu Uva, you do not have a smart battery, you have
a control method battery.

For a CM battery, the OS can poll the battery state by calling _BST, or
set a trip point (via _BTP) and the OS will get an interrupt when the
battery crosses that trip.

Regards -- Andy


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Re: question about ACPI & Smart Batteries

[Cintia B. Margi]

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* Grover, Andrew (andrew.grover-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org) said:
> Unless you have a Fujitsu Uva, you do not have a smart battery, you have
> a control method battery.

I don't have a smart battery then.
 
> For a CM battery, the OS can poll the battery state by calling _BST, or
> set a trip point (via _BTP) and the OS will get an interrupt when the
> battery crosses that trip.

I do not want to set a trip point, but I would like to monitor the battery discharge
process... I want to characterize the battery discharge behavior under different tasks,
so I intend to monitor the battery voltage and the discharge rate (which I can obtain
from /proc/acpi/battery/BAT0/state). What I would like to know is how often the state
file is updated and how accurate these values are. Any idea where I can get this info?

Thanks,

Cintia 

--
Cintia Margi
Graduate Student
SoE - UCSC
http://www.soe.ucsc.edu/~cintia
GPG Public Key: http://www.soe.ucsc.edu/~cintia/cintia.gpg
B4DE 9355 3840 FF72 50F2 ACAC E2EC AA9A 41E2 CD55

[-- Attachment #2: Type: application/pgp-signature, Size: 187 bytes --]

Re: question about ACPI & Smart Batteries

[Tomasz Ciolek]

Write to the maintainer of wmacpi-ng package. He has a good clue as to
how ACPI generates the battery values...

Tomasz Ciolek

On Thu, Aug 12, 2004 at 03:29:36PM -0700, Cintia B. Margi wrote:
> * Grover, Andrew (andrew.grover-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org) said:
> > Unless you have a Fujitsu Uva, you do not have a smart battery, you have
> > a control method battery.
> 
> I don't have a smart battery then.
>  
> > For a CM battery, the OS can poll the battery state by calling _BST, or
> > set a trip point (via _BTP) and the OS will get an interrupt when the
> > battery crosses that trip.
> 
> I do not want to set a trip point, but I would like to monitor the battery discharge
> process... I want to characterize the battery discharge behavior under different tasks,
> so I intend to monitor the battery voltage and the discharge rate (which I can obtain
> from /proc/acpi/battery/BAT0/state). What I would like to know is how often the state
> file is updated and how accurate these values are. Any idea where I can get this info?
> 
> Thanks,
> 
> Cintia 
> 
> --
> Cintia Margi
> Graduate Student
> SoE - UCSC
> http://www.soe.ucsc.edu/~cintia
> GPG Public Key: http://www.soe.ucsc.edu/~cintia/cintia.gpg
> B4DE 9355 3840 FF72 50F2 ACAC E2EC AA9A 41E2 CD55



-- 
Tomasz M. Ciolek	
*******************************************************************************
 tmc at dreamcraft dot com dot au 
*******************************************************************************
   GPG Key ID:		0x41C4C2F0
   GPG Key Fingerprint: 3883 B308 8256 2246 D3ED  A1FF 3A1D 0EAD 41C4 C2F0
   Key available on www.pgp.net	
*******************************************************************************


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Re: question about ACPI & Smart Batteries

[Paul Ionescu]

Hi Cintia,

In CM case I think that when you look into /proc/acpi/battery/BAT0/state,
you get the instantaneous value.
So the state file is not updated unless you look in it, and then you get
the values at that moment, because the APCI code will just call _BST
method to tell you the actual values.
So, I think you can trust those values as being pretty accurate.

Paul


On Thu, 12 Aug 2004 15:29:36 -0700, Cintia B. Margi wrote:
>> For a CM battery, the OS can poll the battery state by calling _BST, or
>> set a trip point (via _BTP) and the OS will get an interrupt when the
>> battery crosses that trip.
> 
> I do not want to set a trip point, but I would like to monitor the
> battery discharge process... I want to characterize the battery
> discharge behavior under different tasks, so I intend to monitor the
> battery voltage and the discharge rate (which I can obtain from
> /proc/acpi/battery/BAT0/state). What I would like to know is how often
> the state file is updated and how accurate these values are. Any idea
> where I can get this info?
> 
> Thanks,
> 
> Cintia




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Re: Re: question about ACPI & Smart Batteries

[Karol Kozimor]

Thus wrote Paul Ionescu:
> In CM case I think that when you look into /proc/acpi/battery/BAT0/state,
> you get the instantaneous value.
> So the state file is not updated unless you look in it, and then you get
> the values at that moment, because the APCI code will just call _BST
> method to tell you the actual values.
> So, I think you can trust those values as being pretty accurate.

I suppose most ECs cache that information and update only in EC-specific
intervals.
Best regards,

-- 
Karol 'sziwan' Kozimor
sziwan-DETuoxkZsSqrDJvtcaxF/A@public.gmane.org


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