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:

     •   four single-ended inputs

     •   three differential inputs (one input line is shared between all three
         inputs)

     •   two single-ended inputs and one differential input

     •   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
     <avg@FreeBSD.org>.

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 13.1-RELEASE-p6        November 6, 2021        FreeBSD 13.1-RELEASE-p6