From: Andrzej Kaczmarek <andrzej.kaczmarek@tieto.com>
To: Santiago Carot <sancane@gmail.com>
Cc: "linux-bluetooth@vger.kernel.org" <linux-bluetooth@vger.kernel.org>
Subject: Re: [PATCH v2 07/15] thermometer: Reformat MeasurementReceived description
Date: Tue, 2 Oct 2012 10:52:22 +0200 [thread overview]
Message-ID: <506AAB46.3020007@tieto.com> (raw)
In-Reply-To: <CACLukz+Ducgd2LmFCrqyb6TnSz_BSEVm1x=rKXrOzSzKNg6ung@mail.gmail.com>
Hi Santiago,
On 10/01/2012 02:08 PM, Santiago Carot wrote:
>>> Mantissa values must not always be 2^23-1 on special cases.
>>> Information provided here is required for upper profiles which are
>>> implementing an 11073-20601 protocol layer because they have to
>>> differentiate among these values. In my opinion, documentation about
>>> passible values for the mantissa should remain as they are.
>>
>>
>> HTS specification states (see quote below) that measurement value field may
>> be NaN in case sensor is not able to provide valid measurement. So I assume
>> here that either it has valid data or NaN otherwise and thus there's no need
>> to specify other special values as they should not be received here.
>>
>> <quote>
>> The Temperature Measurement Value field may contain special float value NaN
>> (0x007FFFFF) defined in IEEE 11073-20601 [4] to report an invalid result
>> from a computation step or missing data due to the hardware’s inability to
>> provide a valid measurement.
>> </quote>
>>
>
> IMHO that doesn't justify you to force all mantisse values to be
> 2^23-1, first of all because the value type for this characteristic is
> a FLOAT type, so any value that a thermometer could send, it does it
> using the format defined for FLOAT types which is explained in
> IEEE-11073-20601,
> [http://developer.bluetooth.org/gatt/Pages/FormatTypes.aspx]
>
> On the other hand, I understand from this quote that thermometers MAY
> set NaN in case sensor is not able to provide valid measuremen due to
> an invalid result or missing data, but it doesn't say anything about
> other values that a FLOAT types can take, so you are forcing to be NaN
> other special cases that are defined for this kind of type.
>
> If you had a look to that spec you could see wich other special values
> a FLOAT type could take, if not, you could at least have a look to one
> of the whitepapers defined in bluetooth sig for transcoders.
Just to be clear here: I do not force mantissa values to any particular
value. Whatever is received from remote device is still dispatched to
application as-is. I just modified description so it mentions what HTS
specification says about this value and that's all and since it was just
done "by the way" when reformatting description I won't push for it.
But perhaps it's worth just adding note that exponent and mantissa are
as in IEEE-11073-20601. This clearly states that apps working in
IEEE-11073-20601 ecosystem can pack both values directly into float and
there's no need to specify all special values.
BR,
Andrzej
next prev parent reply other threads:[~2012-10-02 8:52 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-01 9:23 [PATCH v2 00/15] Thermometer watchers API changes + fixes Andrzej Kaczmarek
2012-10-01 9:23 ` [PATCH v2 01/15] thermometer: Store thermometer devices per-adapter Andrzej Kaczmarek
2012-10-01 9:23 ` [PATCH v2 02/15] thermometer: Register ThermometerManager interface on adapter path Andrzej Kaczmarek
2012-10-01 9:23 ` [PATCH v2 03/15] thermometer: Move watcher logic to adapter interface Andrzej Kaczmarek
2012-10-01 9:23 ` [PATCH v2 04/15] thermometer: Include remote device information in MeasurementReceived Andrzej Kaczmarek
2012-10-01 9:23 ` [PATCH v2 05/15] thermometer: Update API document Andrzej Kaczmarek
2012-10-01 9:23 ` [PATCH v2 06/15] thermometer: Update test script Andrzej Kaczmarek
2012-10-01 9:23 ` [PATCH v2 07/15] thermometer: Reformat MeasurementReceived description Andrzej Kaczmarek
2012-10-01 9:43 ` Santiago Carot
2012-10-01 11:32 ` Andrzej Kaczmarek
2012-10-01 12:08 ` Santiago Carot
2012-10-02 8:52 ` Andrzej Kaczmarek [this message]
2012-10-03 7:41 ` Santiago Carot
2012-10-01 9:23 ` [PATCH v2 08/15] thermometer: Change string properties to lower-case Andrzej Kaczmarek
2012-10-01 9:23 ` [PATCH v2 09/15] thermometer: Update driver naming style Andrzej Kaczmarek
2012-10-01 9:23 ` [PATCH v2 10/15] thermometer: Add constant definition for watcher interface name Andrzej Kaczmarek
2012-10-01 9:23 ` [PATCH v2 11/15] thermometer: Add common function to write characteristics CCC Andrzej Kaczmarek
2012-10-01 9:23 ` [PATCH v2 12/15] thermometer: Refactor processing of measurement characteristic value Andrzej Kaczmarek
2012-10-01 9:23 ` [PATCH v2 13/15] thermometer: Fix whitespace Andrzej Kaczmarek
2012-10-01 9:23 ` [PATCH v2 14/15] thermometer: Fix indentation Andrzej Kaczmarek
2012-10-01 9:23 ` [PATCH v2 15/15] thermometer: Fix missing braces Andrzej Kaczmarek
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