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- Kernel driver ntc_thermistor
- =================
- Supported thermistors from Murata:
- * Murata NTC Thermistors NCP15WB473, NCP18WB473, NCP21WB473, NCP03WB473, NCP15WL333
- Prefixes: 'ncp15wb473', 'ncp18wb473', 'ncp21wb473', 'ncp03wb473', 'ncp15wl333'
- 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.
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