Root/
1 | Kernel driver adt7462 |
2 | ====================== |
3 | |
4 | Supported chips: |
5 | * Analog Devices ADT7462 |
6 | Prefix: 'adt7462' |
7 | Addresses scanned: I2C 0x58, 0x5C |
8 | Datasheet: Publicly available at the Analog Devices website |
9 | |
10 | Author: Darrick J. Wong |
11 | |
12 | Description |
13 | ----------- |
14 | |
15 | This driver implements support for the Analog Devices ADT7462 chip family. |
16 | |
17 | This chip is a bit of a beast. It has 8 counters for measuring fan speed. It |
18 | can also measure 13 voltages or 4 temperatures, or various combinations of the |
19 | two. See the chip documentation for more details about the exact set of |
20 | configurations. This driver does not allow one to configure the chip; that is |
21 | left to the system designer. |
22 | |
23 | A sophisticated control system for the PWM outputs is designed into the ADT7462 |
24 | that allows fan speed to be adjusted automatically based on any of the three |
25 | temperature sensors. Each PWM output is individually adjustable and |
26 | programmable. Once configured, the ADT7462 will adjust the PWM outputs in |
27 | response to the measured temperatures without further host intervention. This |
28 | feature can also be disabled for manual control of the PWM's. |
29 | |
30 | Each of the measured inputs (voltage, temperature, fan speed) has |
31 | corresponding high/low limit values. The ADT7462 will signal an ALARM if |
32 | any measured value exceeds either limit. |
33 | |
34 | The ADT7462 samples all inputs continuously. The driver will not read |
35 | the registers more often than once every other second. Further, |
36 | configuration data is only read once per minute. |
37 | |
38 | Special Features |
39 | ---------------- |
40 | |
41 | The ADT7462 have a 10-bit ADC and can therefore measure temperatures |
42 | with 0.25 degC resolution. |
43 | |
44 | The Analog Devices datasheet is very detailed and describes a procedure for |
45 | determining an optimal configuration for the automatic PWM control. |
46 | |
47 | The driver will report sensor labels when it is able to determine that |
48 | information from the configuration registers. |
49 | |
50 | Configuration Notes |
51 | ------------------- |
52 | |
53 | Besides standard interfaces driver adds the following: |
54 | |
55 | * PWM Control |
56 | |
57 | * pwm#_auto_point1_pwm and temp#_auto_point1_temp and |
58 | * pwm#_auto_point2_pwm and temp#_auto_point2_temp - |
59 | |
60 | point1: Set the pwm speed at a lower temperature bound. |
61 | point2: Set the pwm speed at a higher temperature bound. |
62 | |
63 | The ADT7462 will scale the pwm between the lower and higher pwm speed when |
64 | the temperature is between the two temperature boundaries. PWM values range |
65 | from 0 (off) to 255 (full speed). Fan speed will be set to maximum when the |
66 | temperature sensor associated with the PWM control exceeds temp#_max. |
67 | |
68 |
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Tags:
od-2011-09-04
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