| 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. |