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Commit | Line | Data |
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f22aaaa7 | 1 | Kernel driver ntc_thermistor |
b04f2f7d | 2 | ============================ |
f22aaaa7 | 3 | |
8b6f5e0f | 4 | Supported thermistors from Murata: |
b04f2f7d | 5 | |
887ee434 | 6 | * Murata NTC Thermistors NCP15WB473, NCP18WB473, NCP21WB473, NCP03WB473, |
54ce3a0d | 7 | NCP15WL333, NCP03WF104, NCP15XH103 |
b04f2f7d | 8 | |
887ee434 | 9 | Prefixes: 'ncp15wb473', 'ncp18wb473', 'ncp21wb473', 'ncp03wb473', |
54ce3a0d | 10 | 'ncp15wl333', 'ncp03wf104', 'ncp15xh103' |
b04f2f7d | 11 | |
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12 | Datasheet: Publicly available at Murata |
13 | ||
ed67f087 | 14 | Supported thermistors from EPCOS: |
b04f2f7d | 15 | |
ed67f087 | 16 | * EPCOS NTC Thermistors B57330V2103 |
b04f2f7d | 17 | |
ed67f087 | 18 | Prefixes: b57330v2103 |
b04f2f7d | 19 | |
ed67f087 JP |
20 | Datasheet: Publicly available at EPCOS |
21 | ||
f22aaaa7 DK |
22 | Other NTC thermistors can be supported simply by adding compensation |
23 | tables; e.g., NCP15WL333 support is added by the table ncpXXwl333. | |
24 | ||
25 | Authors: | |
b04f2f7d | 26 | |
f22aaaa7 DK |
27 | MyungJoo Ham <myungjoo.ham@samsung.com> |
28 | ||
29 | Description | |
30 | ----------- | |
31 | ||
8b6f5e0f NKC |
32 | The NTC (Negative Temperature Coefficient) thermistor is a simple thermistor |
33 | that requires users to provide the resistance and lookup the corresponding | |
34 | compensation table to get the temperature input. | |
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35 | |
36 | The NTC driver provides lookup tables with a linear approximation function | |
37 | and four circuit models with an option not to use any of the four models. | |
38 | ||
b04f2f7d MCC |
39 | Using the following convention:: |
40 | ||
41 | $ resistor | |
42 | [TH] the thermistor | |
43 | ||
f22aaaa7 DK |
44 | The four circuit models provided are: |
45 | ||
b04f2f7d MCC |
46 | 1. connect = NTC_CONNECTED_POSITIVE, pullup_ohm > 0:: |
47 | ||
48 | [pullup_uV] | |
49 | | | | |
50 | [TH] $ (pullup_ohm) | |
51 | | | | |
52 | +----+-----------------------[read_uV] | |
53 | | | |
54 | $ (pulldown_ohm) | |
55 | | | |
56 | -+- (ground) | |
57 | ||
58 | 2. connect = NTC_CONNECTED_POSITIVE, pullup_ohm = 0 (not-connected):: | |
59 | ||
60 | [pullup_uV] | |
61 | | | |
62 | [TH] | |
63 | | | |
64 | +----------------------------[read_uV] | |
65 | | | |
66 | $ (pulldown_ohm) | |
67 | | | |
68 | -+- (ground) | |
69 | ||
70 | 3. connect = NTC_CONNECTED_GROUND, pulldown_ohm > 0:: | |
71 | ||
72 | [pullup_uV] | |
73 | | | |
74 | $ (pullup_ohm) | |
75 | | | |
76 | +----+-----------------------[read_uV] | |
77 | | | | |
78 | [TH] $ (pulldown_ohm) | |
79 | | | | |
80 | -+----+- (ground) | |
81 | ||
82 | 4. connect = NTC_CONNECTED_GROUND, pulldown_ohm = 0 (not-connected):: | |
83 | ||
84 | [pullup_uV] | |
85 | | | |
86 | $ (pullup_ohm) | |
87 | | | |
88 | +----------------------------[read_uV] | |
89 | | | |
90 | [TH] | |
91 | | | |
92 | -+- (ground) | |
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93 | |
94 | When one of the four circuit models is used, read_uV, pullup_uV, pullup_ohm, | |
95 | pulldown_ohm, and connect should be provided. When none of the four models | |
96 | are suitable or the user can get the resistance directly, the user should | |
97 | provide read_ohm and _not_ provide the others. | |
98 | ||
99 | Sysfs Interface | |
100 | --------------- | |
f22aaaa7 | 101 | |
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102 | =============== == ============================================================= |
103 | name the mandatory global attribute, the thermistor name. | |
104 | =============== == ============================================================= | |
105 | temp1_type RO always 4 (thermistor) | |
f22aaaa7 | 106 | |
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107 | temp1_input RO measure the temperature and provide the measured value. |
108 | (reading this file initiates the reading procedure.) | |
109 | =============== == ============================================================= | |
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110 | |
111 | Note that each NTC thermistor has only _one_ thermistor; thus, only temp1 exists. |