1 Kernel driver ntc_thermistor 2 ============================ 3 4 Supported thermistors from Murata: 5 6 * Murata NTC Thermistors NCP15WB473, NCP18WB473, NCP21WB473, NCP03WB473, 7 NCP15WL333, NCP03WF104, NCP15XH103 8 9 Prefixes: 'ncp15wb473', 'ncp18wb473', 'ncp21wb473', 'ncp03wb473', 10 'ncp15wl333', 'ncp03wf104', 'ncp15xh103' 11 12 Datasheet: Publicly available at Murata 13 14 Supported thermistors from EPCOS: 15 16 * EPCOS NTC Thermistors B57330V2103 17 18 Prefixes: b57330v2103 19 20 Datasheet: Publicly available at EPCOS 21 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: 26 27 MyungJoo Ham <myungjoo.ham@samsung.com> 28 29 Description 30 ----------- 31 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. 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 39 Using the following convention:: 40 41 $ resistor 42 [TH] the thermistor 43 44 The four circuit models provided are: 45 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) 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 --------------- 101 102 =============== == ============================================================= 103 name the mandatory global attribute, the thermistor name. 104 =============== == ============================================================= 105 temp1_type RO always 4 (thermistor) 106 107 temp1_input RO measure the temperature and provide the measured value. 108 (reading this file initiates the reading procedure.) 109 =============== == ============================================================= 110 111 Note that each NTC thermistor has only _one_ thermistor; thus, only temp1 exists.
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