Based on kernel version 3.19. Page generated on 2015-02-13 21:21 EST.
1 Kernel driver lm83 2 ================== 3 4 Supported chips: 5 * National Semiconductor LM83 6 Prefix: 'lm83' 7 Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e 8 Datasheet: Publicly available at the National Semiconductor website 9 http://www.national.com/pf/LM/LM83.html 10 * National Semiconductor LM82 11 Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e 12 Datasheet: Publicly available at the National Semiconductor website 13 http://www.national.com/pf/LM/LM82.html 14 15 16 Author: Jean Delvare <firstname.lastname@example.org> 17 18 Description 19 ----------- 20 21 The LM83 is a digital temperature sensor. It senses its own temperature as 22 well as the temperature of up to three external diodes. The LM82 is 23 a stripped down version of the LM83 that only supports one external diode. 24 Both are compatible with many other devices such as the LM84 and all 25 other ADM1021 clones. The main difference between the LM83 and the LM84 26 in that the later can only sense the temperature of one external diode. 27 28 Using the adm1021 driver for a LM83 should work, but only two temperatures 29 will be reported instead of four. 30 31 The LM83 is only found on a handful of motherboards. Both a confirmed 32 list and an unconfirmed list follow. If you can confirm or infirm the 33 fact that any of these motherboards do actually have an LM83, please 34 contact us. Note that the LM90 can easily be misdetected as a LM83. 35 36 Confirmed motherboards: 37 SBS P014 38 SBS PSL09 39 40 Unconfirmed motherboards: 41 Gigabyte GA-8IK1100 42 Iwill MPX2 43 Soltek SL-75DRV5 44 45 The LM82 is confirmed to have been found on most AMD Geode reference 46 designs and test platforms. 47 48 The driver has been successfully tested by Magnus Forsström, who I'd 49 like to thank here. More testers will be of course welcome. 50 51 The fact that the LM83 is only scarcely used can be easily explained. 52 Most motherboards come with more than just temperature sensors for 53 health monitoring. They also have voltage and fan rotation speed 54 sensors. This means that temperature-only chips are usually used as 55 secondary chips coupled with another chip such as an IT8705F or similar 56 chip, which provides more features. Since systems usually need three 57 temperature sensors (motherboard, processor, power supply) and primary 58 chips provide some temperature sensors, the secondary chip, if needed, 59 won't have to handle more than two temperatures. Thus, ADM1021 clones 60 are sufficient, and there is no need for a four temperatures sensor 61 chip such as the LM83. The only case where using an LM83 would make 62 sense is on SMP systems, such as the above-mentioned Iwill MPX2, 63 because you want an additional temperature sensor for each additional 64 CPU. 65 66 On the SBS P014, this is different, since the LM83 is the only hardware 67 monitoring chipset. One temperature sensor is used for the motherboard 68 (actually measuring the LM83's own temperature), one is used for the 69 CPU. The two other sensors must be used to measure the temperature of 70 two other points of the motherboard. We suspect these points to be the 71 north and south bridges, but this couldn't be confirmed. 72 73 All temperature values are given in degrees Celsius. Local temperature 74 is given within a range of 0 to +85 degrees. Remote temperatures are 75 given within a range of 0 to +125 degrees. Resolution is 1.0 degree, 76 accuracy is guaranteed to 3.0 degrees (see the datasheet for more 77 details). 78 79 Each sensor has its own high limit, but the critical limit is common to 80 all four sensors. There is no hysteresis mechanism as found on most 81 recent temperature sensors. 82 83 The lm83 driver will not update its values more frequently than every 84 other second; reading them more often will do no harm, but will return 85 'old' values.