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1 | Kernel driver lm83 |
2 | ================== | |
3 | ||
4 | Supported chips: | |
b04f2f7d | 5 | |
7f15b664 | 6 | * National Semiconductor LM83 |
b04f2f7d | 7 | |
7f15b664 | 8 | Prefix: 'lm83' |
b04f2f7d | 9 | |
7f15b664 | 10 | Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e |
b04f2f7d | 11 | |
7f15b664 | 12 | Datasheet: Publicly available at the National Semiconductor website |
b04f2f7d MCC |
13 | |
14 | http://www.national.com/pf/LM/LM83.html | |
15 | ||
43cb7ebe | 16 | * National Semiconductor LM82 |
b04f2f7d | 17 | |
43cb7ebe | 18 | Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e |
b04f2f7d | 19 | |
43cb7ebe | 20 | Datasheet: Publicly available at the National Semiconductor website |
7f15b664 | 21 | |
b04f2f7d | 22 | http://www.national.com/pf/LM/LM82.html |
7f15b664 | 23 | |
7c81c60f | 24 | Author: Jean Delvare <jdelvare@suse.de> |
7f15b664 M |
25 | |
26 | Description | |
27 | ----------- | |
28 | ||
29 | The LM83 is a digital temperature sensor. It senses its own temperature as | |
43cb7ebe JC |
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. | |
7f15b664 M |
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: | |
b04f2f7d | 45 | === ===== |
7f15b664 | 46 | SBS P014 |
114cc0c0 | 47 | SBS PSL09 |
b04f2f7d | 48 | === ===== |
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49 | |
50 | Unconfirmed motherboards: | |
b04f2f7d | 51 | =========== ========== |
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52 | Gigabyte GA-8IK1100 |
53 | Iwill MPX2 | |
54 | Soltek SL-75DRV5 | |
b04f2f7d | 55 | =========== ========== |
7f15b664 | 56 | |
43cb7ebe JC |
57 | The LM82 is confirmed to have been found on most AMD Geode reference |
58 | designs and test platforms. | |
59 | ||
be2a608b | 60 | The driver has been successfully tested by Magnus Forsström, who I'd |
7f15b664 M |
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. |