Messages in this thread | | | From | Jason Wortham <> | Date | Tue, 13 Mar 2012 17:04:25 -0700 | Subject | RE: [PATCH 4/5] max17042: Fix value scaling for VCELL and avgVCELL |
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Ok, the datasheet is written that way as a commitment about the hardware ADC accuracy/resolution. However, the ADC performs a set of 8x samples, and as a result will have an average which provides some additional "fake" resolution. Even though this extra resolution isn't strong in an analog way, it's still useful information.
But I guess I'm really splitting hairs here since it's such a small resolution.
--Jason
-----Original Message----- From: Dirk Brandewie [mailto:dirk.brandewie@gmail.com] Sent: Tuesday, March 13, 2012 3:59 PM To: Jason Wortham Cc: bruce robertson; Anton Vorontsov; dirk.brandewie@gmail.com; linux-kernel@vger.kernel.org; dg77.kim@samsung.com; kyungmin.park@samsung.com; myungjoo.ham@samsung.com Subject: Re: [PATCH 4/5] max17042: Fix value scaling for VCELL and avgVCELL
On 03/13/2012 02:04 PM, Jason Wortham wrote: > The bottom 3 bits are still functional bits and aren't required to be masked. Arguably these bits are below the hardware accuracy of the ADC, however, they still provide some averaging information. >
The datasheet for the 17042 shows the bottom three bits as don't care that was the reason for the mask.
If Jason says it is still accurate without the mask I am fine with it.
--Dirk > --Jason > > -----Original Message----- > From: bruce robertson [mailto:bruce.e.robertson@intel.com] > Sent: Tuesday, March 13, 2012 2:00 PM > To: Anton Vorontsov > Cc: dirk.brandewie@gmail.com; linux-kernel@vger.kernel.org; dg77.kim@samsung.com; kyungmin.park@samsung.com; myungjoo.ham@samsung.com; Jason Wortham > Subject: Re: [PATCH 4/5] max17042: Fix value scaling for VCELL and avgVCELL > > Anton Vorontsov<cbouatmailru@gmail.com> writes: > >> On Tue, Jan 24, 2012 at 09:26:07AM -0800, dirk.brandewie@gmail.com wrote: >>> From: Bruce Robertson<bruce.e.robertson@intel.com> >>> >>> The bottom three bits of the register are don't care bits. The LSB >>> value is 625 uV. Adjust the returned values appropriately >>> >>> Signed-off-by: Bruce Robertson<bruce.e.robertson@intel.com> >>> Signed-off-by: Dirk Brandewie<dirk.brandewie@gmail.com> >>> Acked-by: MyungJoo Ham<myungjoo.ham@samsung.com> >> >> I guess this was fixed long ago by the following patch: >> >> commit cf7a8c03db792894f436db5f3ffc44d947b9b068 >> Author: MyungJoo Ham<myungjoo.ham@samsung.com> >> Date: Wed Aug 17 10:18:34 2011 +0900 >> >> max17042_battery: Bugfix of incorrect voltage register value interpretation >> >> The calculation had error in getting voltage values from >> MAX17042 registers. The least bit denotes 78.125uV (625/8). > > The multipliers I see in the patch are 83 making the voltages somewhat > high and the low 3 bits are not masked off. I'm probably misreading the code. > >> >> Signed-off-by: MyungJoo Ham<myungjoo.ham@samsung.com> >> Signed-off-by: Philip Rakity<prakity@marvell.com> >> Signed-off-by: Kyungmin Park<kyungmin.park@samsung.com> >> Signed-off-by: Anton Vorontsov<cbouatmailru@gmail.com> >> >> Thanks,
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