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:

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).