101 lines
2.6 KiB
Plaintext
Executable file
101 lines
2.6 KiB
Plaintext
Executable file
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 <myungjoo.ham@samsung.com>
|
|
|
|
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.
|
|
|
|
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.
|