1.\" 2.\" SPDX-License-Identifier: BSD-2-Clause 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.Dd November 6, 2021 28.Dt PCF8591 4 29.Os 30.Sh NAME 31.Nm pcf8591 32.Nd driver for the PCF8591 8-bit A/D and D/A converter 33.Sh SYNOPSIS 34To compile this driver into the kernel, 35place the following lines in your 36kernel configuration file: 37.Bd -ragged -offset indent 38.Cd "device pcf8591" 39.Cd "device iicbus" 40.Ed 41.Pp 42Alternatively, to load the driver as a 43module at boot time, place the following line in 44.Xr loader.conf 5 : 45.Bd -literal -offset indent 46pcf8591_load="YES" 47.Ed 48.Sh DESCRIPTION 49The 50.Nm 51driver supports reading four inputs and setting one output over I2C. 52The hardware supports configuring the input lines as: 53.Bl -bullet 54.It 55four single-ended inputs 56.It 57three differential inputs (one input line is shared between all three inputs) 58.It 59two single-ended inputs and one differential input 60.It 61two differential inputs. 62.El 63.Pp 64The 65.Nm 66driver reports data via 67.Xr sysctl 8 68entries in the device's node in the 69.Xr sysctl 8 70tree: 71.Bl -tag -width inputs.%d 72.It Va inputs.%d 73The input level of the corresponding input in steps between 0 and 255. 74Absolute voltage depends on an actual reference voltage. 75.El 76.Pp 77On an 78.Xr FDT 4 79based system the following properties must be set: 80.Bl -tag -width "compatible" 81.It Va compatible 82Must be set to "nxp,pcf8591". 83.It Va reg 84The I2C address of 85.Nm . 86It should be in the range from 0x40 to 0x4f (7-bit). 87.El 88.Pp 89The DTS part for a 90.Nm 91device usually looks like: 92.Bd -literal 93/ { 94 95 ... 96 pcf8591adc { 97 compatible = "nxp,pcf8591"; 98 reg = <0x48>; 99 }; 100}; 101.Ed 102.Sh SEE ALSO 103.Xr fdt 4 , 104.Xr iicbus 4 , 105.Xr sysctl 8 106.Sh HISTORY 107The 108.Nm 109driver and this manual page was written by 110.An Andriy Gapon Aq Mt avg@FreeBSD.org . 111.Sh BUGS 112The 113.Nm 114driver does not support changing the input configuration. 115All input lines are configured as single-ended inputs. 116.Pp 117The 118.Nm 119driver does not support setting the output. 120It is always disabled (tri-state). 121