1Kernel driver ntc_thermistor 2============================ 3 4Supported 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 14Supported thermistors from EPCOS: 15 16* EPCOS NTC Thermistors B57330V2103 17 18 Prefixes: b57330v2103 19 20 Datasheet: Publicly available at EPCOS 21 22Other NTC thermistors can be supported simply by adding compensation 23tables; e.g., NCP15WL333 support is added by the table ncpXXwl333. 24 25Authors: 26 27 MyungJoo Ham <myungjoo.ham@samsung.com> 28 29Description 30----------- 31 32The NTC (Negative Temperature Coefficient) thermistor is a simple thermistor 33that requires users to provide the resistance and lookup the corresponding 34compensation table to get the temperature input. 35 36The NTC driver provides lookup tables with a linear approximation function 37and four circuit models with an option not to use any of the four models. 38 39Using the following convention:: 40 41 $ resistor 42 [TH] the thermistor 43 44The four circuit models provided are: 45 461. 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) 57 582. 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) 69 703. 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) 81 824. 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 94When one of the four circuit models is used, read_uV, pullup_uV, pullup_ohm, 95pulldown_ohm, and connect should be provided. When none of the four models 96are suitable or the user can get the resistance directly, the user should 97provide read_ohm and _not_ provide the others. 98 99Sysfs Interface 100--------------- 101 102=============== == ============================================================= 103name the mandatory global attribute, the thermistor name. 104=============== == ============================================================= 105temp1_type RO always 4 (thermistor) 106 107temp1_input RO measure the temperature and provide the measured value. 108 (reading this file initiates the reading procedure.) 109=============== == ============================================================= 110 111Note that each NTC thermistor has only _one_ thermistor; thus, only temp1 exists. 112