1.\" 2.\" SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3.\" 4.\" Copyright (c) 2020 Andriy Gapon <avg@FreeBSD.org> 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25.\" SUCH DAMAGE. 26.\" 27.\" $FreeBSD: head/share/man/man4/cp2112.4 364144 2020-08-12 09:42:05Z avg $ 28.\" 29.Dd November 6, 2021 30.Dt PCF8591 4 31.Os 32.Sh NAME 33.Nm pcf8591 34.Nd driver for the PCF8591 8-bit A/D and D/A converter 35.Sh SYNOPSIS 36To compile this driver into the kernel, 37place the following lines in your 38kernel configuration file: 39.Bd -ragged -offset indent 40.Cd "device pcf8591" 41.Cd "device iicbus" 42.Ed 43.Pp 44Alternatively, to load the driver as a 45module at boot time, place the following line in 46.Xr loader.conf 5 : 47.Bd -literal -offset indent 48pcf8591_load="YES" 49.Ed 50.Sh DESCRIPTION 51The 52.Nm 53driver supports reading four inputs and setting one output over I2C. 54The hardware supports configuring the input lines as: 55.Bl -bullet 56.It 57four single-ended inputs 58.It 59three differential inputs (one input line is shared between all three inputs) 60.It 61two single-ended inputs and one differential input 62.It 63two differential inputs. 64.El 65.Pp 66The 67.Nm 68driver reports data via 69.Xr sysctl 8 70entries in the device's node in the 71.Xr sysctl 8 72tree: 73.Bl -tag -width inputs.%d 74.It Va inputs.%d 75The input level of the corresponding input in steps between 0 and 255. 76Absolute voltage depends on an actual reference voltage. 77.El 78.Pp 79On an 80.Xr FDT 4 81based system the following properties must be set: 82.Bl -tag -width "compatible" 83.It Va compatible 84Must be set to "nxp,pcf8591". 85.It Va reg 86The I2C address of 87.Nm . 88It should be in the range from 0x40 to 0x4f (7-bit). 89.El 90.Pp 91The DTS part for a 92.Nm 93device usually looks like: 94.Bd -literal 95/ { 96 97 ... 98 pcf8591adc { 99 compatible = "nxp,pcf8591"; 100 reg = <0x48>; 101 }; 102}; 103.Ed 104.Sh SEE ALSO 105.Xr fdt 4 , 106.Xr iicbus 4 , 107.Xr sysctl 8 108.Sh HISTORY 109The 110.Nm 111driver and this manual page was written by 112.An Andriy Gapon Aq Mt avg@FreeBSD.org . 113.Sh BUGS 114The 115.Nm 116driver does not support changing the input configuration. 117All input lines are configured as single-ended inputs. 118.Pp 119The 120.Nm 121driver does not support setting the output. 122It is always disabled (tri-state). 123