106 lines
3.4 KiB
Groff
106 lines
3.4 KiB
Groff
.\" $NetBSD: mcp48x1dac.4,v 1.2 2015/08/23 20:07:16 wiz Exp $
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.\"
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.\" Copyright (c) 2015 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Radoslaw Kujawa.
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Frank Wille.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd August 23, 2015
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.Dt MCP48X1DAC 4
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.Os
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.Sh NAME
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.Nm mcp48x1dac
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.Nd Microchip 48x1 digital to analog converter
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.Sh SYNOPSIS
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.Cd "mcp48x1dac* at spi? slave ? flags N"
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.Sh DESCRIPTION
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The
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.Nm
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driver supports the MCP48x1 family of digital to analog converters.
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The digital
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values to be converted to analog signal are passed through the
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.Xr sysctl 8
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node.
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.Pp
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The driver reports the current voltage output on the chip's DAC channel
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through the
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.Xr envsys 4
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API.
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It calculates these values assuming that internal 2.048V reference voltage
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.Li ( Vref )
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is used.
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.Pp
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The following table shows the supported chips.
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The type of the chip can be selected with the
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.Ar flags
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argument in the config file.
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.Bl -column "Designation" "Resolution" "flags" -offset indent
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.It Sy "Designation" Ta Sy "Resolution" Ta Sy "flags"
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.It Li "MCP4801" Ta "8 bits" Ta "0"
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.It Li "MCP4811" Ta "10 bits" Ta "1"
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.It Li "MCP4821" Ta "12 bits" Ta "2"
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.El
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.Sh SYSCTL VARIABLES
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The following
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.Xr sysctl 3
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variables are provided:
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.Bl -tag -width indent
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.It machdep.mcp48x1dac0.data
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Defines digital data to be converted into analog signal.
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This value is interpreted literally and sent to the DAC without any conversion.
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Refer to the chip datasheet for more information.
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.It machdep.mcp48x1dac0.gain
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When set to 1 it enables 2x output gain on the DAC channel.
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The default value is 0.
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.El
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.Sh SEE ALSO
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.Xr envsys 4 ,
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.Xr spi 4 ,
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.Xr sysctl 8
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.Rs
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.%T MCP4801/4811/4821 8/10/12-Bit Voltage Output Digital-to-Analog Converter \
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with Internal VREF and SPI Interface Data Sheet
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.Re
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.Sh HISTORY
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The
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.Nm
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driver first appeared in
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.Nx 7.0 .
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.Sh AUTHORS
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.An -nosplit
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The
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.Nm
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driver was written by
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.An Radoslaw Kujawa .
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.Pp
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This man page is based on
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.Xr mcp3kadc 4
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page by
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.An Frank Wille .
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.Sh BUGS
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There are bugs.
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