PCF8591(4)

📦 version 15.1, in freebsd 14.5, freebsd 15.1, nixpkgs unstable

🎀 NAME 🎀

okay bestie, welcome to PCF8591(4) — the page from the Kernel Interfaces Manual — and it's literally about the 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 this little icon:

/ {

        ...
        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).

xoxo 💋 this page is from Debian, dated November 6, 2021, and its footer name is PCF8591(4) — bye bestie 🫶

📦 where this page comes from