ntc_thermistor
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Kernel driver ntc_thermistor
=================
Supported thermistors:
* Murata NTC Thermistors NCP15WB473, NCP18WB473, NCP21WB473, NCP03WB473, NCP15WL333
Prefixes: 'ncp15wb473', 'ncp18wb473', 'ncp21wb473', 'ncp03wb473', 'ncp15wl333'
Datasheet: Publicly available at Murata
Other NTC thermistors can be supported simply by adding compensation
tables; e.g., NCP15WL333 support is added by the table ncpXXwl333.
Authors:
MyungJoo Ham <myungjoo.ham@samsung.com>
Description
-----------
The NTC thermistor is a simple thermistor that requires users to provide the
resistance and lookup the corresponding compensation table to get the
temperature input.
The NTC driver provides lookup tables with a linear approximation function
and four circuit models with an option not to use any of the four models.
The four circuit models provided are:
$: resister, [TH]: the thermistor
1. connect = NTC_CONNECTED_POSITIVE, pullup_ohm > 0
[pullup_uV]
| |
[TH] $ (pullup_ohm)
| |
+----+-----------------------[read_uV]
|
$ (pulldown_ohm)
|
--- (ground)
2. connect = NTC_CONNECTED_POSITIVE, pullup_ohm = 0 (not-connected)
[pullup_uV]
|
[TH]
|
+----------------------------[read_uV]
|
$ (pulldown_ohm)
|
--- (ground)
3. connect = NTC_CONNECTED_GROUND, pulldown_ohm > 0
[pullup_uV]
|
$ (pullup_ohm)
|
+----+-----------------------[read_uV]
| |
[TH] $ (pulldown_ohm)
| |
-------- (ground)
4. connect = NTC_CONNECTED_GROUND, pulldown_ohm = 0 (not-connected)
[pullup_uV]
|
$ (pullup_ohm)
|
+----------------------------[read_uV]
|
[TH]
|
--- (ground)
When one of the four circuit models is used, read_uV, pullup_uV, pullup_ohm,
pulldown_ohm, and connect should be provided. When none of the four models
are suitable or the user can get the resistance directly, the user should
provide read_ohm and _not_ provide the others.
Sysfs Interface
---------------
name the mandatory global attribute, the thermistor name.
temp1_type always 4 (thermistor)
RO
temp1_input measure the temperature and provide the measured value.
(reading this file initiates the reading procedure.)
RO
Note that each NTC thermistor has only _one_ thermistor; thus, only temp1 exists.