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S16A User’s Guide Overview
EDT, Inc. October, 1996 1
Overview
The S16A SBus 16-bit Dual Analog Interface is a single-slot board for SBus-based computer systems. The
S16A has two analog I/O channels, each incorporating one 16-bit Analog-to-Digital (ADC) converter and
one 20-bit Digital-to-Analog (DAC) converter. The S16A is designed for continuous input and output on
both channels simultaneously and is typically used for scientific and medical research and development.
The S16A employs two Burr-Brown
®
PCM1702 analog output DACs running at a sample rate of 705.6KHz,
which is 16 times the standard audio frequency of 44.1 KHz.
The two S16A analog input ADCs are National Semiconductor
®
ADC16071s, running with a base sampling
rate of 192KHz. The S16A provides a clock prescale register to divide this frequency down for lower rates.
The S16A uses the SBus DMA interface and can transmit or receive any amount of data to and from host
memory continuously on both channels at once.
Each I/O channel’s input ADC can monitor a differential signal, either of the two differential inputs as a
single-ended signal, either of two I/O channels’ DAC outputs, or a reference ground. The ability to monitor
the outputs directly or ground allows the S16A to be tested and adjusted using these internal loop-backs.
A portion of the functionality of the S16A is contained in a sub-assembly, the Analog Input Module. This
module is controlled and configured using a byte-sequence protocol, as described in the section Analog
Input Module Control Protocol beginning on page 34.
The S16A boards fully support the requirements of the SunOS operating system. Example programs are
included. Each of the two I/O channels appears as two subdevices to the SunOS operating system, one for
input and one for output, for a total of four subdevices.
This document explains how to install the S16A interface and driver and how to write applications for it. It
is divided into the following sections:
Installation describes how to install the board and its related software.
Input and Output describes the programming interface library.
Hardware Interface Protocol provides a connector pin-out diagram and describes the S16A signals
and timing.
Registers describes the hardware registers.
Specifications lists the product specifications.
References lists other documentation resources that may be helpful.
Contacting EDT describes how to contact EDT, and how to access EDT resources on the
Internet.