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 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. Using the following convention:: $ resistor [TH] the thermistor The four circuit models provided are: 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 RO always 4 (thermistor) temp1_input RO measure the temperature and provide the measured value. (reading this file initiates the reading procedure.) =============== == ============================================================= Note that each NTC thermistor has only _one_ thermistor; thus, only temp1 exists.