About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Documentation / hwmon / lm77




Custom Search

Based on kernel version 3.16. Page generated on 2014-08-06 21:39 EST.

1	Kernel driver lm77
2	==================
3	
4	Supported chips:
5	  * National Semiconductor LM77
6	    Prefix: 'lm77'
7	    Addresses scanned: I2C 0x48 - 0x4b
8	    Datasheet: Publicly available at the National Semiconductor website
9	               http://www.national.com/
10	
11	Author: Andras BALI <drewie@freemail.hu>
12	
13	Description
14	-----------
15	
16	The LM77 implements one temperature sensor. The temperature
17	sensor incorporates a band-gap type temperature sensor,
18	10-bit ADC, and a digital comparator with user-programmable upper
19	and lower limit values.
20	
21	The LM77 implements 3 limits: low (temp1_min), high (temp1_max) and
22	critical (temp1_crit.) It also implements an hysteresis mechanism which
23	applies to all 3 limits. The relative difference is stored in a single
24	register on the chip, which means that the relative difference between
25	the limit and its hysteresis is always the same for all 3 limits.
26	
27	This implementation detail implies the following:
28	* When setting a limit, its hysteresis will automatically follow, the
29	  difference staying unchanged. For example, if the old critical limit
30	  was 80 degrees C, and the hysteresis was 75 degrees C, and you change
31	  the critical limit to 90 degrees C, then the hysteresis will
32	  automatically change to 85 degrees C.
33	* All 3 hysteresis can't be set independently. We decided to make
34	  temp1_crit_hyst writable, while temp1_min_hyst and temp1_max_hyst are
35	  read-only. Setting temp1_crit_hyst writes the difference between
36	  temp1_crit_hyst and temp1_crit into the chip, and the same relative
37	  hysteresis applies automatically to the low and high limits.
38	* The limits should be set before the hysteresis.
Hide Line Numbers
About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Information is copyright its respective author. All material is available from the Linux Kernel Source distributed under a GPL License. This page is provided as a free service by mjmwired.net.