.\" $NetBSD: mcp48x1dac.4,v 1.2 2015/08/23 20:07:16 wiz Exp $
.\"
.\" Copyright (c) 2015 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Radoslaw Kujawa.
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Frank Wille.
.\"
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.\" modification, are permitted provided that the following conditions
.\" are met:
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.\"    notice, this list of conditions and the following disclaimer.
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.Dd August 23, 2015
.Dt MCP48X1DAC 4
.Os
.Sh NAME
.Nm mcp48x1dac
.Nd Microchip 48x1 digital to analog converter
.Sh SYNOPSIS
.Cd "mcp48x1dac* at spi? slave ? flags N"
.Sh DESCRIPTION
The
.Nm
driver supports the MCP48x1 family of digital to analog converters.
The digital
values to be converted to analog signal are passed through the
.Xr sysctl 8
node.
.Pp
The driver reports the current voltage output on the chip's DAC channel
through the
.Xr envsys 4
API.
It calculates these values assuming that internal 2.048V reference voltage
.Li ( Vref )
is used.
.Pp
The following table shows the supported chips.
The type of the chip can be selected with the
.Ar flags
argument in the config file.
.Bl -column "Designation" "Resolution" "flags" -offset indent
.It Sy "Designation" Ta Sy "Resolution" Ta Sy "flags"
.It Li "MCP4801" Ta "8 bits" Ta "0"
.It Li "MCP4811" Ta "10 bits" Ta "1"
.It Li "MCP4821" Ta "12 bits" Ta "2"
.El
.Sh SYSCTL VARIABLES
The following
.Xr sysctl 3
variables are provided:
.Bl -tag -width indent
.It machdep.mcp48x1dac0.data
Defines digital data to be converted into analog signal.
This value is interpreted literally and sent to the DAC without any conversion.
Refer to the chip datasheet for more information.
.It machdep.mcp48x1dac0.gain
When set to 1 it enables 2x output gain on the DAC channel.
The default value is 0.
.El
.Sh SEE ALSO
.Xr envsys 4 ,
.Xr spi 4 ,
.Xr sysctl 8
.Rs
.%T MCP4801/4811/4821 8/10/12-Bit Voltage Output Digital-to-Analog Converter \
with Internal VREF and SPI Interface Data Sheet
.Re
.Sh HISTORY
The
.Nm
driver first appeared in
.Nx 7.0 .
.Sh AUTHORS
.An -nosplit
The
.Nm
driver was written by
.An Radoslaw Kujawa .
.Pp
This man page is based on
.Xr mcp3kadc 4
page by
.An Frank Wille .
.Sh BUGS
There are bugs.