PCF8591(4) FreeBSD Kernel Interfaces Manual PCF8591(4)
NAME
pcf8591 - driver for the PCF8591 8-bit A/D and D/A converter
SYNOPSIS
To compile this driver into the kernel, place the following lines in your
kernel configuration file:
device pcf8591
device iicbus
Alternatively, to load the driver as a module at boot time, place the
following line in loader.conf(5):
pcf8591_load="YES"
DESCRIPTION
The pcf8591 driver supports reading four inputs and setting one output
over I2C. The hardware supports configuring the input lines as:
o four single-ended inputs
o three differential inputs (one input line is shared between all three
inputs)
o two single-ended inputs and one differential input
o two differential inputs.
The pcf8591 driver reports data via sysctl(8) entries in the device's
node in the sysctl(8) tree:
inputs.%d The input level of the corresponding input in steps between 0
and 255. Absolute voltage depends on an actual reference
voltage.
On an FDT(4) based system the following properties must be set:
compatible Must be set to "nxp,pcf8591".
reg The I2C address of pcf8591. It should be in the range from
0x40 to 0x4f (7-bit).
The DTS part for a pcf8591 device usually looks like:
/ {
...
pcf8591adc {
compatible = "nxp,pcf8591";
reg = <0x48>;
};
};
SEE ALSO
fdt(4), iicbus(4), sysctl(8)
HISTORY
The pcf8591 driver and this manual page was written by Andriy Gapon
<
[email protected]>.
BUGS
The pcf8591 driver does not support changing the input configuration.
All input lines are configured as single-ended inputs.
The pcf8591 driver does not support setting the output. It is always
disabled (tri-state).
FreeBSD 14.1-RELEASE-p8 November 6, 2021 FreeBSD 14.1-RELEASE-p8