Kernel driver ntc_thermistor
============================
Supported thermistors from Murata:
* Murata NTC Thermistors NCP15WB473, NCP18WB473, NCP21WB473, NCP03WB473,
NCP15WL333, NCP03WF104, NCP15XH103
Prefixes: 'ncp15wb473', 'ncp18wb473', 'ncp21wb473', 'ncp03wb473',
'ncp15wl333', 'ncp03wf104', 'ncp15xh103'
Datasheet: Publicly available at Murata
Supported thermistors from EPCOS:
* EPCOS NTC Thermistors B57330V2103
Prefixes: b57330v2103
Datasheet: Publicly available at EPCOS
Other NTC thermistors can be supported simply by adding compensation
tables; e.g., NCP15WL333 support is added by the table ncpXXwl333.
Authors:
MyungJoo Ham <[email protected]>
Description
-----------
The NTC (Negative Temperature Coefficient) 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.
Using the following convention::
$ resistor
[TH] the thermistor
The four circuit models provided are:
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 RO always 4 (thermistor)
temp1_input RO measure the temperature and provide the measured value.
(reading this file initiates the reading procedure.)
=============== == =============================================================
Note that each NTC thermistor has only _one_ thermistor; thus, only temp1 exists.
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