96 lines
3.2 KiB
Groff
96 lines
3.2 KiB
Groff
.\" $NetBSD: mcp3kadc.4,v 1.2 2015/08/19 09:57:41 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 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 18, 2015
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.Dt MCP3KADC 4
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.Os
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.Sh NAME
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.Nm mcp3kadc
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.Nd Microchip 3x0x SAR analog to digital converter
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.Sh SYNOPSIS
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.Cd "mcp3kadc* 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 reports the current voltage on the chip's ADC channels through the
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.Xr envsys 4
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API.
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The driver calculates these values according to the currently selected
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reference voltage
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.Li ( Vref ) .
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It can be changed through the
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.Xr sysctl 8
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node
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.Li hw.mcp3kadc0.vref .
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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" "Input Channels" "flags" -offset indent
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.It Sy "Designation" Ta Sy "Resolution" Ta Sy "Input Channels" Ta Sy "flags"
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.It Li "MCP3001" Ta "10 bits" Ta "1" Ta "0"
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.It Li "MCP3002" Ta "10 bits" Ta "2" Ta "1"
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.It Li "MCP3004" Ta "10 bits" Ta "4" Ta "2"
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.It Li "MCP3008" Ta "10 bits" Ta "8" Ta "3"
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.It Li "MCP3201" Ta "12 bits" Ta "1" Ta "4"
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.It Li "MCP3202" Ta "12 bits" Ta "2" Ta "5"
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.It Li "MCP3204" Ta "12 bits" Ta "4" Ta "6"
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.It Li "MCP3208" Ta "12 bits" Ta "8" Ta "7"
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.It Li "MCP3301" Ta "13 bits" Ta "1" Ta "8"
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.It Li "MCP3302" Ta "13 bits" Ta "4" Ta "9"
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.It Li "MCP3304" Ta "13 bits" Ta "8" Ta "10"
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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 hw.mcp3kadc0.vref
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Defines the reference voltage on the chip's
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.Li Vref
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pin in millivolts (mV).
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It defaults to the ADC's maximum output value + 1
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in millivolts (e.g., 4096 for a 12-bit ADC).
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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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.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 8.0 .
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.Sh AUTHORS
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The
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.Nm
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driver was written by
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.An Frank Wille .
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