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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:02:30 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:02:30 +0000
commit76cb841cb886eef6b3bee341a2266c76578724ad (patch)
treef5892e5ba6cc11949952a6ce4ecbe6d516d6ce58 /Documentation/hwmon/ntc_thermistor
parentInitial commit. (diff)
downloadlinux-upstream/4.19.249.tar.xz
linux-upstream/4.19.249.zip
Adding upstream version 4.19.249.upstream/4.19.249upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+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.