1 Kernel driver lm83 2 ================== 3 4 Supported chips: 5 6 * National Semiconductor LM83 7 8 Prefix: 'lm83' 9 10 Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e 11 12 Datasheet: Publicly available at the National Semiconductor website 13 14 http://www.national.com/pf/LM/LM83.html 15 16 * National Semiconductor LM82 17 18 Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e 19 20 Datasheet: Publicly available at the National Semiconductor website 21 22 http://www.national.com/pf/LM/LM82.html 23 24 Author: Jean Delvare <jdelvare@suse.de> 25 26 Description 27 ----------- 28 29 The LM83 is a digital temperature sensor. It senses its own temperature as 30 well as the temperature of up to three external diodes. The LM82 is 31 a stripped down version of the LM83 that only supports one external diode. 32 Both are compatible with many other devices such as the LM84 and all 33 other ADM1021 clones. The main difference between the LM83 and the LM84 34 in that the later can only sense the temperature of one external diode. 35 36 Using the adm1021 driver for a LM83 should work, but only two temperatures 37 will be reported instead of four. 38 39 The LM83 is only found on a handful of motherboards. Both a confirmed 40 list and an unconfirmed list follow. If you can confirm or infirm the 41 fact that any of these motherboards do actually have an LM83, please 42 contact us. Note that the LM90 can easily be misdetected as a LM83. 43 44 Confirmed motherboards: 45 === ===== 46 SBS P014 47 SBS PSL09 48 === ===== 49 50 Unconfirmed motherboards: 51 =========== ========== 52 Gigabyte GA-8IK1100 53 Iwill MPX2 54 Soltek SL-75DRV5 55 =========== ========== 56 57 The LM82 is confirmed to have been found on most AMD Geode reference 58 designs and test platforms. 59 60 The driver has been successfully tested by Magnus Forsström, who I'd 61 like to thank here. More testers will be of course welcome. 62 63 The fact that the LM83 is only scarcely used can be easily explained. 64 Most motherboards come with more than just temperature sensors for 65 health monitoring. They also have voltage and fan rotation speed 66 sensors. This means that temperature-only chips are usually used as 67 secondary chips coupled with another chip such as an IT8705F or similar 68 chip, which provides more features. Since systems usually need three 69 temperature sensors (motherboard, processor, power supply) and primary 70 chips provide some temperature sensors, the secondary chip, if needed, 71 won't have to handle more than two temperatures. Thus, ADM1021 clones 72 are sufficient, and there is no need for a four temperatures sensor 73 chip such as the LM83. The only case where using an LM83 would make 74 sense is on SMP systems, such as the above-mentioned Iwill MPX2, 75 because you want an additional temperature sensor for each additional 76 CPU. 77 78 On the SBS P014, this is different, since the LM83 is the only hardware 79 monitoring chipset. One temperature sensor is used for the motherboard 80 (actually measuring the LM83's own temperature), one is used for the 81 CPU. The two other sensors must be used to measure the temperature of 82 two other points of the motherboard. We suspect these points to be the 83 north and south bridges, but this couldn't be confirmed. 84 85 All temperature values are given in degrees Celsius. Local temperature 86 is given within a range of 0 to +85 degrees. Remote temperatures are 87 given within a range of 0 to +125 degrees. Resolution is 1.0 degree, 88 accuracy is guaranteed to 3.0 degrees (see the datasheet for more 89 details). 90 91 Each sensor has its own high limit, but the critical limit is common to 92 all four sensors. There is no hysteresis mechanism as found on most 93 recent temperature sensors. 94 95 The lm83 driver will not update its values more frequently than every 96 other second; reading them more often will do no harm, but will return 97 'old' values.
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.