ad.4

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)ad.4	8.1	9/11/90
.TH ad 4 VAX "" Unsupported
.SH Name
ad \- Data Translation A/D converter
.SH Syntax
.B "device ad0 at uba0 csr 0170400 vector adintr"
.SH Description
The
.PN ad
converter provides the interface to the Data Translation A/D converter.
This is
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 A/D board.
.PP
The driver communicates to a user process by means of ioctls.
The AD_CHAN ioctl selects which channel of the board to read.
For example,
.br
.in +.5i
chan = 5;
ioctl(fd, AD_CHAN, &chan);
.in -.5i
selects channel 5.
The AD_READ ioctl actually reads the data and returns it to the user
process.
An example is
.br
.in +.5i
ioctl(fd, AD_READ, &data);
.in -.5i
.SH Files
.PN /dev/ad