Root/
1 | --------------------------------- |
2 | AD525x Digital Potentiometers |
3 | --------------------------------- |
4 | |
5 | The ad525x_dpot driver exports a simple sysfs interface. This allows you to |
6 | work with the immediate resistance settings as well as update the saved startup |
7 | settings. Access to the factory programmed tolerance is also provided, but |
8 | interpretation of this settings is required by the end application according to |
9 | the specific part in use. |
10 | |
11 | --------- |
12 | Files |
13 | --------- |
14 | |
15 | Each dpot device will have a set of eeprom, rdac, and tolerance files. How |
16 | many depends on the actual part you have, as will the range of allowed values. |
17 | |
18 | The eeprom files are used to program the startup value of the device. |
19 | |
20 | The rdac files are used to program the immediate value of the device. |
21 | |
22 | The tolerance files are the read-only factory programmed tolerance settings |
23 | and may vary greatly on a part-by-part basis. For exact interpretation of |
24 | this field, please consult the datasheet for your part. This is presented |
25 | as a hex file for easier parsing. |
26 | |
27 | ----------- |
28 | Example |
29 | ----------- |
30 | |
31 | Locate the device in your sysfs tree. This is probably easiest by going into |
32 | the common i2c directory and locating the device by the i2c slave address. |
33 | |
34 | # ls /sys/bus/i2c/devices/ |
35 | 0-0022 0-0027 0-002f |
36 | |
37 | So assuming the device in question is on the first i2c bus and has the slave |
38 | address of 0x2f, we descend (unrelated sysfs entries have been trimmed). |
39 | |
40 | # ls /sys/bus/i2c/devices/0-002f/ |
41 | eeprom0 rdac0 tolerance0 |
42 | |
43 | You can use simple reads/writes to access these files: |
44 | |
45 | # cd /sys/bus/i2c/devices/0-002f/ |
46 | |
47 | # cat eeprom0 |
48 | 0 |
49 | # echo 10 > eeprom0 |
50 | # cat eeprom0 |
51 | 10 |
52 | |
53 | # cat rdac0 |
54 | 5 |
55 | # echo 3 > rdac0 |
56 | # cat rdac0 |
57 | 3 |
58 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9