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Date: Wed, 30 Mar 2016 17:58:41 +0200
From: Maxime Jayat <jayatmaxime@...il.com>
To: Joseph McNally <jmcna06@...il.com>
Cc: Jean Delvare <jdelvare@...e.de>,
Guenter Roeck <linux@...ck-us.net>, lm-sensors@...sensors.org,
linux-kernel@...r.kernel.org
Subject: Re: ncpXXxh103 compensation values?
I don't think it is wrong to use ncpXXxh103 instead of ncp15xh103,
because the first number refers to the physical size of the thermistor
and should not change its behavior. In fact the datasheet does the same
kind of grouping.
I was just wondering what was the reason for the discrepancy between the
datasheet and your values.
Indeed the datasheet I linked earlier, at page 15, gives you verbatim
the content of this array and the result of your calculation does not
match it.
It is not _absurdly_ wrong but, at first sight, it seems like there is a
10 degrees difference at the extremes (but 10 kOhm at 25 C is correct).
Le 30/03/2016 17:09, Joseph McNally a écrit :
> Hello Maxime,
>
> This data was calculated for a Murata NCP15XH103XXXXX.
>
> You have illustrated something to me with your question though. When I
> uploaded this patch, I was following the format of the compensation
> tables that are already present in the file. So i used "ncpXXxh103"
> instead of "ncp15xh103". Also, it was my first patch submitted to the
> Linux kernel. So I may have been over thinking some things! With some
> hindsight, I see that the name is misleading. I'm going to have to
> revisit this patch to make it more 'generic' for other thermistors, or
> make it more specific for this particular thermistor.
>
> I hope that answers your questions. Thanks for pointing this out to me.
>
> Regards,
> Joseph
>
> On Wed, Mar 30, 2016 at 3:03 PM, Maxime Jayat <jayatmaxime@...il.com
> <mailto:jayatmaxime@...il.com>> wrote:
>
> Hello Joseph,
>
> You recently added support for the ncpXXxh103 in
> drivers/hwmon/ntc_thermistor.c with the following array of values:
>
> +static const struct ntc_compensation ncpXXxh103[] = {
> + { .temp_c = -40, .ohm = 247565 },
> + { .temp_c = -35, .ohm = 181742 },
> + { .temp_c = -30, .ohm = 135128 },
> + { .temp_c = -25, .ohm = 101678 },
> + { .temp_c = -20, .ohm = 77373 },
> + { .temp_c = -15, .ohm = 59504 },
> + { .temp_c = -10, .ohm = 46222 },
> + { .temp_c = -5, .ohm = 36244 },
> + { .temp_c = 0, .ohm = 28674 },
> + { .temp_c = 5, .ohm = 22878 },
> + { .temp_c = 10, .ohm = 18399 },
> + { .temp_c = 15, .ohm = 14910 },
> + { .temp_c = 20, .ohm = 12169 },
> + { .temp_c = 25, .ohm = 10000 },
> + { .temp_c = 30, .ohm = 8271 },
> + { .temp_c = 35, .ohm = 6883 },
> + { .temp_c = 40, .ohm = 5762 },
> + { .temp_c = 45, .ohm = 4851 },
> + { .temp_c = 50, .ohm = 4105 },
> + { .temp_c = 55, .ohm = 3492 },
> + { .temp_c = 60, .ohm = 2985 },
> + { .temp_c = 65, .ohm = 2563 },
> + { .temp_c = 70, .ohm = 2211 },
> + { .temp_c = 75, .ohm = 1915 },
> + { .temp_c = 80, .ohm = 1666 },
> + { .temp_c = 85, .ohm = 1454 },
> + { .temp_c = 90, .ohm = 1275 },
> + { .temp_c = 95, .ohm = 1121 },
> + { .temp_c = 100, .ohm = 990 },
> + { .temp_c = 105, .ohm = 876 },
> + { .temp_c = 110, .ohm = 779 },
> + { .temp_c = 115, .ohm = 694 },
> + { .temp_c = 120, .ohm = 620 },
> + { .temp_c = 125, .ohm = 556 },
> +};
> +
>
> Where are these taken from?
> Unlike the other thermistors in the file, these values don't seem to
> match anything in the Murata NTC Thermistor Datasheet.
> See:
> http://www.murata.com/~/media/webrenewal/support/library/catalog/products/thermistor/ntc/r44e.ashx
>
> --
> Maxime Jayat
>
>
--
Maxime Jayat
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