1 Kernel driver lm73
2 ==================
3
4 Supported chips:
5
6 * Texas Instruments LM73
7
8 Prefix: 'lm73'
9
10 Addresses scanned: I2C 0x48, 0x49, 0x4a, 0
11
12 Datasheet: Publicly available at the Texas
13
14 https://www.ti.com/product/lm73
15
16
17 Author: Guillaume Ligneul <guillaume.ligneul@gm
18
19 Documentation: Chris Verges <kg4ysn@gmail.com>
20
21
22 Description
23 -----------
24
25 The LM73 is a digital temperature sensor. All
26 given in degrees Celsius.
27
28 Measurement Resolution Support
29 ------------------------------
30
31 The LM73 supports four resolutions, defined in
32 LSB: 0.25, 0.125, 0.0625, and 0.3125. Changin
33 affects the conversion time of the LM73's anal
34 From userspace, the desired resolution can be
35 conversion time via the 'update_interval' sysf
36 device. This attribute will normalize ranges
37 maximum times defined for the resolution in th
38
39 ============= ============= ============
40 Resolution Conv. Time Input Range
41 (C/LSB) (msec) (msec)
42 ============= ============= ============
43 0.25 14 0..14
44 0.125 28 15..28
45 0.0625 56 29..56
46 0.03125 112 57..infinity
47 ============= ============= ============
48
49 The following examples show how the 'update_in
50 used to change the conversion time::
51
52 $ echo 0 > update_interval
53 $ cat update_interval
54 14
55 $ cat temp1_input
56 24250
57
58 $ echo 22 > update_interval
59 $ cat update_interval
60 28
61 $ cat temp1_input
62 24125
63
64 $ echo 56 > update_interval
65 $ cat update_interval
66 56
67 $ cat temp1_input
68 24062
69
70 $ echo 85 > update_interval
71 $ cat update_interval
72 112
73 $ cat temp1_input
74 24031
75
76 As shown here, the lm73 driver automatically a
77 'update_interval' via a step function. Readin
78 'update_interval' value after a write operatio
79 conversion time actively in use.
80
81 Mathematically, the resolution can be derived
82 via the following function:
83
84 g(x) = 0.250 * [log(x/14) / log(2)]
85
86 where 'x' is the output from 'update_interval'
87 resolution in degrees C per LSB.
88
89 Alarm Support
90 -------------
91
92 The LM73 features a simple over-temperature al
93 feature is exposed via the sysfs attributes.
94
95 The attributes 'temp1_max_alarm' and 'temp1_mi
96 provided by the LM73 that indicate whether the
97 passed the 'temp1_max' and 'temp1_min' thresho
98 values _must_ be read to clear the registers o
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