.\" $NetBSD: mcp3kadc.4,v 1.2 2015/08/19 09:57:41 wiz Exp $
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.\" Copyright (c) 2015 The NetBSD Foundation, Inc.
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.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Frank Wille.
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.Dd August 18, 2015
.Dt MCP3KADC 4
.Os
.Sh NAME
.Nm mcp3kadc
.Nd Microchip 3x0x SAR analog to digital converter
.Sh SYNOPSIS
.Cd "mcp3kadc* at spi? slave ? flags N"
.Sh DESCRIPTION
The
.Nm
driver reports the current voltage on the chip's ADC channels through the
.Xr envsys 4
API.
The driver calculates these values according to the currently selected
reference voltage
.Li ( Vref ) .
It can be changed through the
.Xr sysctl 8
node
.Li hw.mcp3kadc0.vref .
.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" "Input Channels" "flags" -offset indent
.It Sy "Designation" Ta Sy "Resolution" Ta Sy "Input Channels" Ta Sy "flags"
.It Li "MCP3001" Ta "10 bits" Ta "1" Ta "0"
.It Li "MCP3002" Ta "10 bits" Ta "2" Ta "1"
.It Li "MCP3004" Ta "10 bits" Ta "4" Ta "2"
.It Li "MCP3008" Ta "10 bits" Ta "8" Ta "3"
.It Li "MCP3201" Ta "12 bits" Ta "1" Ta "4"
.It Li "MCP3202" Ta "12 bits" Ta "2" Ta "5"
.It Li "MCP3204" Ta "12 bits" Ta "4" Ta "6"
.It Li "MCP3208" Ta "12 bits" Ta "8" Ta "7"
.It Li "MCP3301" Ta "13 bits" Ta "1" Ta "8"
.It Li "MCP3302" Ta "13 bits" Ta "4" Ta "9"
.It Li "MCP3304" Ta "13 bits" Ta "8" Ta "10"
.El
.Sh SYSCTL VARIABLES
The following
.Xr sysctl 3
variables are provided:
.Bl -tag -width indent
.It hw.mcp3kadc0.vref
Defines the reference voltage on the chip's
.Li Vref
pin in millivolts (mV).
It defaults to the ADC's maximum output value + 1
in millivolts (e.g., 4096 for a 12-bit ADC).
.El
.Sh SEE ALSO
.Xr envsys 4 ,
.Xr spi 4 ,
.Xr sysctl 8
.Sh HISTORY
The
.Nm
driver first appeared in
.Nx 8.0 .
.Sh AUTHORS
The
.Nm
driver was written by
.An Frank Wille .