NOTE: This driver has not been ported from
4.4BSD yet.
The
ad driver provides an 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.
The driver communicates to a user process by means of
ioctl(2)s. The
AD_CHAN ioctl(2) selects which channel of the board to read. For example,
chan = 5;
ioctl(fd, AD_CHAN, &chan);
selects channel 5. The
AD_READ ioctl(2) actually reads the data and returns it to the user process. An example is
ioctl(fd, AD_READ, &data);