1 Kernel driver adt7470
2 =====================
3
4 Supported chips:
5
6 * Analog Devices ADT7470
7
8 Prefix: 'adt7470'
9
10 Addresses scanned: I2C 0x2C, 0x2E, 0x2F
11
12 Datasheet: Publicly available at the Analo
13
14 Author: Darrick J. Wong
15
16 Description
17 -----------
18
19 This driver implements support for the Analog
20 be other chips that implement this interface.
21
22 The ADT7470 uses the 2-wire interface compatib
23 specification. Using an analog to digital conv
24 external temperatures. It has four (4) 16-bit
25 There are four (4) PWM outputs that can be use
26
27 A sophisticated control system for the PWM out
28 that allows fan speed to be adjusted automatic
29 temperature sensors. Each PWM output is indivi
30 programmable. Once configured, the ADT7470 wil
31 response to the measured temperatures with fur
32 feature can also be disabled for manual contro
33
34 Each of the measured inputs (temperature, fan
35 limit values. The ADT7470 will signal an ALARM
36 either limit.
37
38 The ADT7470 samples all inputs continuously.
39 the purpose of periodically querying the tempe
40 automatic fan pwm control to set the fan speed
41 registers more often than once every 5 seconds
42 only read once per minute.
43
44 Special Features
45 ----------------
46
47 The ADT7470 has a 8-bit ADC and is capable of
48 degC resolution.
49
50 The Analog Devices datasheet is very detailed
51 determining an optimal configuration for the a
52
53 Configuration Notes
54 -------------------
55
56 Besides standard interfaces driver adds the fo
57
58 * PWM Control
59
60 * pwm#_auto_point1_pwm and pwm#_auto_point1_te
61 * pwm#_auto_point2_pwm and pwm#_auto_point2_te
62
63 - point1: Set the pwm speed at a lower tempe
64 - point2: Set the pwm speed at a higher temp
65
66 The ADT7470 will scale the pwm between the low
67 the temperature is between the two temperature
68 from 0 (off) to 255 (full speed). Fan speed w
69 temperature sensor associated with the PWM con
70 pwm#_auto_point2_temp.
71
72 The driver also allows control of the PWM freq
73
74 * pwm1_freq
75
76 The PWM frequency is rounded to the nearest on
77
78 * 11.0 Hz
79 * 14.7 Hz
80 * 22.1 Hz
81 * 29.4 Hz
82 * 35.3 Hz
83 * 44.1 Hz
84 * 58.8 Hz
85 * 88.2 Hz
86 * 1.4 kHz
87 * 22.5 kHz
88
89 Notes
90 -----
91
92 The temperature inputs no longer need to be re
93 order for the automatic pwm algorithm to run.
94 versions of the driver.
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