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4 .\" Copyright (c) 2020 Andriy Gapon <avg@FreeBSD.org>
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32 .Nd driver for the PCF8574 8-bit I2C IO expander
34 To compile this driver into the kernel,
35 place the following lines in your
36 kernel configuration file:
37 .Bd -ragged -offset indent
43 Alternatively, to load the driver as a
44 module at boot time, place the following line in
46 .Bd -literal -offset indent
54 control over 8 GPIO pins.
55 The pins are quasi-bidirectional.
56 Only low output can be actively driven.
57 High output is equivalent to input.
61 based system the following properties must be set:
62 .Bl -tag -width "compatible"
64 Must be set to "nxp,pcf8574".
72 device usually looks like:
78 compatible = "nxp,pcf8574";
90 driver and this manual page was written by
91 .An Andriy Gapon Aq Mt avg@FreeBSD.org .
95 driver does not support the input change interrupt
96 that the hardware provides.