From: Jonathan Cameron <jic23@cam.ac.uk>
To: "Hennerich, Michael" <Michael.Hennerich@analog.com>
Cc: "Cai, Cliff" <Cliff.Cai@analog.com>,
"linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Drivers <Drivers@analog.com>,
"device-drivers-devel@blackfin.uclinux.org"
<device-drivers-devel@blackfin.uclinux.org>,
Cliff Cai <cliff@analog.com>
Subject: Re: [PATCH RESEND v2]IIO driver for Analog Devices Digital Output Gyroscope ADXRS450
Date: Tue, 22 Mar 2011 10:42:38 +0000 [thread overview]
Message-ID: <4D887D1E.90503@cam.ac.uk> (raw)
In-Reply-To: <544AC56F16B56944AEC3BD4E3D5917713754315B05@LIMKCMBX1.ad.analog.com>
On 03/22/11 08:16, Hennerich, Michael wrote:
> Cai, Cliff wrote on 2011-03-22:
>>
>>
>>> -----Original Message-----
>>> From: Jonathan Cameron [mailto:jic23@cam.ac.uk]
>>> Sent: 2011年3月22日 1:40
>>> To: Cai, Cliff
>>> Cc: linux-iio@vger.kernel.org; linux-kernel@vger.kernel.org; Drivers;
>>> device-drivers-devel@blackfin.uclinux.org; Cliff Cai
>>> Subject: Re: [PATCH RESEND v2]IIO driver for Analog Devices Digital
>>> Output Gyroscope ADXRS450
>>>
>>> On 03/19/11 09:27, cliff.cai@analog.com wrote:
>>>> From: Cliff Cai <cliff.cai@analog.com>
>>>>
>>>> Change v2:v1:
>>>>
>>>> Make modification according to Michael Hennerich's comments,
>>>> correct the spi transfer way,use existing sysfs interfaces.
>>> Hi Cliff,
>>>
>>> As you are proposing a couple of new interfaces we need to have
>>> documentation for them. They are quad and dynamic_null_correction. We
>>> need to first establish whether they are of general utility and hence
>>> should be in the main abi doc. The quadrature one isn't something I've
>>> seen before. Is it common in gyros?
>>
>> I'm not sure about this.
>> Michael,do you have any ideas?
>
> The ADXRS450 is a quite new part and features a new sensor design -
> So I don't think the quadrature error is to date very common.
> It might become in future...
>
> From the datasheet:
>
> "The quad sensor design rejects linear and angular
> acceleration, including external g-forces and vibration. This is
> achieved by mechanically coupling the four sensing structures
> such that external g-forces appear as common-mode signals
> that can be removed by the fully differential architecture implemented in the ADXRS450."
>
> "The quad memory registers contain a value corresponding to the amount of
> quadrature error present in the device at a given time.
> Quadrature can be likened to a measurement of the error of the motion of the
> resonator structure, and can be caused by stresses and aging effects.
> The quadrature data is filtered to 80 Hz and can be read frequently to
> detect sudden shifts in the level of quadrature.
> The data is presented as a 16-bit, twos complement number."
>
Cool. So what is a good general name for this? I guess from this description
if it were in a multi axis device you would have this measure for each axis?
So perhaps gyro_z_quadrature_correction_raw? This thing also looks
rather similar to a dynamically changing calibbias. Perhaps we need another
term for a general dynamic linear (I think this is linear) correction inside
a device?
Perhaps go with a gyro specific term for now and wait to see if we get
many more parts with this feature...
>>
>>> Dynamic null correction looks like it should be gyro_z_calibbias to
>>> me but I could be wrong. The doc says "
>>> The user can make small adjustments to the rateout of the device by
>>> asserting these bits. This 10-bit register allows the user to adjust
>>> the static rateout of the device by up to ±6.4°/sec.
>>> "
>>>
>>> which makes me think it is an internally applied offset on the output
>>> signal and hence calibbias in our abi.
>>
>> Thanks
>>
>>> Other than that, various minor nitpicks inline.
>>>
>>> Jonathan
>
> Greetings,
> Michael
>
> --
> Analog Devices GmbH Wilhelm-Wagenfeld-Str. 6 80807 Muenchen
> Sitz der Gesellschaft: Muenchen; Registergericht: Muenchen HRB 40368; Geschaeftsfuehrer:Dr.Carsten Suckrow, Thomas Wessel, William A. Martin, Margaret Seif
>
next prev parent reply other threads:[~2011-03-22 10:41 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-19 9:27 [PATCH RESEND v2]IIO driver for Analog Devices Digital Output Gyroscope ADXRS450 cliff.cai
2011-03-21 17:40 ` Jonathan Cameron
2011-03-22 7:29 ` Cai, Cliff
2011-03-22 8:16 ` Hennerich, Michael
2011-03-22 10:42 ` Jonathan Cameron [this message]
2011-03-23 9:34 ` Hennerich, Michael
2011-03-23 10:22 ` Cai, Cliff
2011-03-23 11:10 ` Jonathan Cameron
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4D887D1E.90503@cam.ac.uk \
--to=jic23@cam.ac.uk \
--cc=Cliff.Cai@analog.com \
--cc=Drivers@analog.com \
--cc=Michael.Hennerich@analog.com \
--cc=cliff@analog.com \
--cc=device-drivers-devel@blackfin.uclinux.org \
--cc=linux-iio@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).