projects / linux-block.git / blame
| Commit | Line | Data |
|---|---|---|
| 7f15b664 M |
1 | Kernel driver lm75 |
| 2 | ================== | |
| 3 | ||
| 4 | Supported chips: | |
| 5 | * National Semiconductor LM75 | |
| 6 | Prefix: 'lm75' | |
| 7 | Addresses scanned: I2C 0x48 - 0x4f | |
| 8 | Datasheet: Publicly available at the National Semiconductor website | |
| 9 | http://www.national.com/ | |
| 05e82fe4 LS |
10 | * National Semiconductor LM75A |
| 11 | Prefix: 'lm75a' | |
| 12 | Addresses scanned: I2C 0x48 - 0x4f | |
| 13 | Datasheet: Publicly available at the National Semiconductor website | |
| 14 | http://www.national.com/ | |
| 7f15b664 M |
15 | * Dallas Semiconductor DS75 |
| 16 | Prefix: 'lm75' | |
| 17 | Addresses scanned: I2C 0x48 - 0x4f | |
| 18 | Datasheet: Publicly available at the Dallas Semiconductor website | |
| 19 | http://www.maxim-ic.com/ | |
| 20 | * Dallas Semiconductor DS1775 | |
| 21 | Prefix: 'lm75' | |
| 22 | Addresses scanned: I2C 0x48 - 0x4f | |
| 23 | Datasheet: Publicly available at the Dallas Semiconductor website | |
| 24 | http://www.maxim-ic.com/ | |
| 25 | * Maxim MAX6625, MAX6626 | |
| 26 | Prefix: 'lm75' | |
| 27 | Addresses scanned: I2C 0x48 - 0x4b | |
| 28 | Datasheet: Publicly available at the Maxim website | |
| 29 | http://www.maxim-ic.com/ | |
| 30 | * Microchip (TelCom) TCN75 | |
| 31 | Prefix: 'lm75' | |
| 32 | Addresses scanned: I2C 0x48 - 0x4f | |
| 33 | Datasheet: Publicly available at the Microchip website | |
| 34 | http://www.microchip.com/ | |
| 35 | ||
| 36 | Author: Frodo Looijaard <frodol@dds.nl> | |
| 37 | ||
| 38 | Description | |
| 39 | ----------- | |
| 40 | ||
| 41 | The LM75 implements one temperature sensor. Limits can be set through the | |
| 42 | Overtemperature Shutdown register and Hysteresis register. Each value can be | |
| 43 | set and read to half-degree accuracy. | |
| 44 | An alarm is issued (usually to a connected LM78) when the temperature | |
| 45 | gets higher then the Overtemperature Shutdown value; it stays on until | |
| 46 | the temperature falls below the Hysteresis value. | |
| 47 | All temperatures are in degrees Celsius, and are guaranteed within a | |
| 48 | range of -55 to +125 degrees. | |
| 49 | ||
| 50 | The LM75 only updates its values each 1.5 seconds; reading it more often | |
| 51 | will do no harm, but will return 'old' values. | |
| 52 | ||
| 53 | The LM75 is usually used in combination with LM78-like chips, to measure | |
| 54 | the temperature of the processor(s). | |
| 55 | ||
| 56 | The DS75, DS1775, MAX6625, and MAX6626 are supported as well. | |
| 57 | They are not distinguished from an LM75. While most of these chips | |
| 58 | have three additional bits of accuracy (12 vs. 9 for the LM75), | |
| 59 | the additional bits are not supported. Not only that, but these chips will | |
| 60 | not be detected if not in 9-bit precision mode (use the force parameter if | |
| 61 | needed). | |
| 62 | ||
| 63 | The TCN75 is supported as well, and is not distinguished from an LM75. | |
| 64 | ||
| 65 | The LM75 is essentially an industry standard; there may be other | |
| 66 | LM75 clones not listed here, with or without various enhancements, | |
| 67 | that are supported. | |
| 68 | ||
| 69 | The LM77 is not supported, contrary to what we pretended for a long time. | |
| 70 | Both chips are simply not compatible, value encoding differs. |