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Based on kernel version 3.16. Page generated on 2014-08-06 21:39 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 <jdelvare@suse.de>
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.
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