NetBSD/share/man/man4/man4.vax/ad.4

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.\" Copyright (c) 1983, 1991 Regents of the University of California.
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.\" from: @(#)ad.4 6.2 (Berkeley) 3/27/91
.\" $Id: ad.4,v 1.2 1993/08/01 07:36:38 mycroft Exp $
.\"
.Dd March 27, 1991
.Dt AD 4 vax
.Os BSD 4.2
.Sh NAME
.Nm ad
.Nd Data Translation A/D converter
.Sh SYNOPSIS
.Cd "device ad0 at uba0 csr 0170400 vector adintr"
.Sh DESCRIPTION
The
.Nm \&ad
driver
provides an interface to the Data Translation A/D converter.
This is
.Em not
a real-time driver, but merely allows
the user process to sample the board's channels one at a time.
Each minor device selects a different
.Tn A/D
board.
.Pp
The driver communicates to a user process by means of
.Xr ioctl 2 Ns s.
The
.Dv AD_CHAN
.Xr ioctl
selects which channel of the board to read.
For example,
.Bd -literal -offset indent
chan = 5;
ioctl(fd, AD_CHAN, &chan);
.Ed
.Pp
selects channel 5.
The
.Dv AD_READ
.Xr ioctl 2
actually reads the data and returns it to the user
process.
An example is
.Bd -literal -offset indent
ioctl(fd, AD_READ, &data);
.Ed
.Sh FILES
.Bl -tag -width /dev/adx -compact
.It Pa /dev/ad
.El
.Sh DIAGNOSTICS
None.
.Sh HISTORY
The
.Nm
driver appeared in
.Bx 4.1 .