diff options
Diffstat (limited to 'Documentation/hwmon/lm90')
| -rw-r--r-- | Documentation/hwmon/lm90 | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/Documentation/hwmon/lm90 b/Documentation/hwmon/lm90 new file mode 100644 index 000000000000..2c4cf39471f4 --- /dev/null +++ b/Documentation/hwmon/lm90 @@ -0,0 +1,121 @@ +Kernel driver lm90 +================== + +Supported chips: + * National Semiconductor LM90 + Prefix: 'lm90' + Addresses scanned: I2C 0x4c + Datasheet: Publicly available at the National Semiconductor website + http://www.national.com/pf/LM/LM90.html + * National Semiconductor LM89 + Prefix: 'lm99' + Addresses scanned: I2C 0x4c and 0x4d + Datasheet: Publicly available at the National Semiconductor website + http://www.national.com/pf/LM/LM89.html + * National Semiconductor LM99 + Prefix: 'lm99' + Addresses scanned: I2C 0x4c and 0x4d + Datasheet: Publicly available at the National Semiconductor website + http://www.national.com/pf/LM/LM99.html + * National Semiconductor LM86 + Prefix: 'lm86' + Addresses scanned: I2C 0x4c + Datasheet: Publicly available at the National Semiconductor website + http://www.national.com/pf/LM/LM86.html + * Analog Devices ADM1032 + Prefix: 'adm1032' + Addresses scanned: I2C 0x4c + Datasheet: Publicly available at the Analog Devices website + http://products.analog.com/products/info.asp?product=ADM1032 + * Analog Devices ADT7461 + Prefix: 'adt7461' + Addresses scanned: I2C 0x4c + Datasheet: Publicly available at the Analog Devices website + http://products.analog.com/products/info.asp?product=ADT7461 + Note: Only if in ADM1032 compatibility mode + * Maxim MAX6657 + Prefix: 'max6657' + Addresses scanned: I2C 0x4c + Datasheet: Publicly available at the Maxim website + http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578 + * Maxim MAX6658 + Prefix: 'max6657' + Addresses scanned: I2C 0x4c + Datasheet: Publicly available at the Maxim website + http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578 + * Maxim MAX6659 + Prefix: 'max6657' + Addresses scanned: I2C 0x4c, 0x4d (unsupported 0x4e) + Datasheet: Publicly available at the Maxim website + http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578 + + +Author: Jean Delvare <khali@linux-fr.org> + + +Description +----------- + +The LM90 is a digital temperature sensor. It senses its own temperature as +well as the temperature of up to one external diode. It is compatible +with many other devices such as the LM86, the LM89, the LM99, the ADM1032, +the MAX6657, MAX6658 and the MAX6659 all of which are supported by this driver. +Note that there is no easy way to differentiate between the last three +variants. The extra address and features of the MAX6659 are not supported by +this driver. Additionally, the ADT7461 is supported if found in ADM1032 +compatibility mode. + +The specificity of this family of chipsets over the ADM1021/LM84 +family is that it features critical limits with hysteresis, and an +increased resolution of the remote temperature measurement. + +The different chipsets of the family are not strictly identical, although +very similar. This driver doesn't handle any specific feature for now, +but could if there ever was a need for it. For reference, here comes a +non-exhaustive list of specific features: + +LM90: + * Filter and alert configuration register at 0xBF. + * ALERT is triggered by temperatures over critical limits. + +LM86 and LM89: + * Same as LM90 + * Better external channel accuracy + +LM99: + * Same as LM89 + * External temperature shifted by 16 degrees down + +ADM1032: + * Consecutive alert register at 0x22. + * Conversion averaging. + * Up to 64 conversions/s. + * ALERT is triggered by open remote sensor. + +ADT7461 + * Extended temperature range (breaks compatibility) + * Lower resolution for remote temperature + +MAX6657 and MAX6658: + * Remote sensor type selection + +MAX6659 + * Selectable address + * Second critical temperature limit + * Remote sensor type selection + +All temperature values are given in degrees Celsius. Resolution +is 1.0 degree for the local temperature, 0.125 degree for the remote +temperature. + +Each sensor has its own high and low limits, plus a critical limit. +Additionally, there is a relative hysteresis value common to both critical +values. To make life easier to user-space applications, two absolute values +are exported, one for each channel, but these values are of course linked. +Only the local hysteresis can be set from user-space, and the same delta +applies to the remote hysteresis. + +The lm90 driver will not update its values more frequently than every +other second; reading them more often will do no harm, but will return +'old' values. + |