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1 | Kernel driver pca9539 | ||
2 | ===================== | ||
3 | |||
4 | NOTE: this driver is deprecated and will be dropped soon, use | ||
5 | drivers/gpio/pca9539.c instead. | ||
6 | |||
7 | Supported chips: | ||
8 | * Philips PCA9539 | ||
9 | Prefix: 'pca9539' | ||
10 | Addresses scanned: none | ||
11 | Datasheet: | ||
12 | http://www.semiconductors.philips.com/acrobat/datasheets/PCA9539_2.pdf | ||
13 | |||
14 | Author: Ben Gardner <bgardner@wabtec.com> | ||
15 | |||
16 | |||
17 | Description | ||
18 | ----------- | ||
19 | |||
20 | The Philips PCA9539 is a 16 bit low power I/O device. | ||
21 | All 16 lines can be individually configured as an input or output. | ||
22 | The input sense can also be inverted. | ||
23 | The 16 lines are split between two bytes. | ||
24 | |||
25 | |||
26 | Detection | ||
27 | --------- | ||
28 | |||
29 | The PCA9539 is difficult to detect and not commonly found in PC machines, | ||
30 | so you have to pass the I2C bus and address of the installed PCA9539 | ||
31 | devices explicitly to the driver at load time via the force=... parameter. | ||
32 | |||
33 | |||
34 | Sysfs entries | ||
35 | ------------- | ||
36 | |||
37 | Each is a byte that maps to the 8 I/O bits. | ||
38 | A '0' suffix is for bits 0-7, while '1' is for bits 8-15. | ||
39 | |||
40 | input[01] - read the current value | ||
41 | output[01] - sets the output value | ||
42 | direction[01] - direction of each bit: 1=input, 0=output | ||
43 | invert[01] - toggle the input bit sense | ||
44 | |||
45 | input reads the actual state of the line and is always available. | ||
46 | The direction defaults to input for all channels. | ||
47 | |||
48 | |||
49 | General Remarks | ||
50 | --------------- | ||
51 | |||
52 | Note that each output, direction, and invert entry controls 8 lines. | ||
53 | You should use the read, modify, write sequence. | ||
54 | For example. to set output bit 0 of 1. | ||
55 | val=$(cat output0) | ||
56 | val=$(( $val | 1 )) | ||
57 | echo $val > output0 | ||
58 | |||