Digilent AIO1 User Manual

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Revision: December 6, 2004 246 East Main | Pullman, WA 99163

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Functional Description

The AIO1 board is a peripheral board designed to work with Digilent’s family of system boards. The
AIO1 contains analog-to-digital and digital -to-analog converters from Analog Devices, two dual op­amps, a variety of analog signal I/O connectors, and a solderless breadboard. All analog components
use an on-board 5VDC voltage source. All unused I/O signals are passed through the AIO1 board so
that it can be used between a system board and other peripheral boards.

The solderless breadboard and op -

Connector J1

amps on the AIO1 can be used to
construct filters and amplifiers for the
data converters. Gain and frequency­limiting resistor/capacitor networks can
be constructed on the breadboard,

unused J2 signals pass through to J4

Connector J3

J1 signals pass through to J3;

and connected to the op-amps and
data converters using jumper wires
inserted into the breadboard
connector. The breadboard connector
can also be used to route analog I/O
signals to any one of eight connectors
included on the board (including BNC,
RCA, and 1/8 audio jacks).

The AIO1 uses an 8-bit, 200Ks
analog-to-digital converter (the

Various I/O

connectors

Solderless

Breadboard

Breadboard connector

AD7823), and an 8-bit, 1Mhz digital-to­analog converter (the AD7303), both
from Analog Devices. The AD8534 op­amps (also from Analog Devices) can

Figure 1: AIO1 block Diagram

drive 250mA outputs rail-to-rail with a
3Mhz bandwidth, so many useful
devices can be driven directly.

The IO1 board uses only twelve signals, all from the J2 connector. Of these, six are provided as
uncommitted digital I/Os (three inputs and three outputs), and six are used by the data converters.
Both data converters use a serial protocol with data signal, clock, and synchronizing signals. Only one
signal is returned to the system board, and it uses a 3.3V buffer so that lower-voltage system boards
can be used.
The J2 connector pin definitions are shown below (all J2 signals not shown pass through to J4).

The AOI1 has two voltage selections available. It can be operated with VCC 3.3V (for the Digilent
Pegasus Board) or 5Vv for all other Digilent System Boards. To use either voltage selection, place a
jumper on JP2 as outlined by the silkscreen on the AIO1.

Connector J2

6 5

Digital I/O

V

IN

V

OUT

All nodes

74CH125

buffer

Data and control

A2D

Converter

(AD 7823)

D2A

Converter

(AD 7303)

Op amps

Serial

data

Copyright Digilent, Inc. All rights reserved 2 pages Doc: 502-035

AIO1 Reference Manual Digilent, Inc. ™

J2 connector pin definitions

J2 pin AIO signal Description

30 DACIN AD7303 data input
31 DACLK AD7303 clock input
29 SYNC AD7303 Sync signal
34 ADOUT AD7823 data output
33 CONVST AD7823 clock input
32 ADCLK AD7823 convert st art signal
38 DIN0
35 DIN1
36 DIN2
28 DOUT0
27 DOUT1
19 DOUT2

The breadboard connector signals are shown in the following table. The breadboard connector allows
various AIO1 signals to be connected to the breadboard using jumper wires. Signals from the BNC
connectors (J5 and J8), the RCA connectors (J6 and J9), and the audio connectors (J7 and J10) are
available, as well as signals from the op-amps and data converters.

Uncommitted digital inputs

Uncommitted digital outputs (use
caution – do not drive above 3.3V)

Breadboard Connector (J11) Signal Definitions

J11 pin

Signal Definition J11 pin Signal Definition

1 VCC33 Regulated voltage 21 OP2AO Op-amp 2A output
2 VU Unregulated voltage 22 OP2BO Op-amp 2B output
3 DI0 Uncommitted digital input 23 OP2BI+ Op-amp 2B input +
4 DO0 Uncommitted digital output 24 OP2BI- Op-amp 2B input ­5 DI1 Uncommitted digital input 25 OP1BI+ Op-amp 1B input +
6 DO1 Uncommitted digital output 26 OP1BI- Op-amp 1B input ­7 DI2 Uncommitted digital input 27 OP1BO Op-amp 1B output
8 DO2 Uncommitted digital output 28 OP1AO Op-amp 1A output

9 J8P BNC post connection 29 OP1AI+ Op-amp 1A input +
10 J8S BNC shield connection 30 OP1AI- Op-amp 1A input ­11 J9P RCA center connection 31 GND System ground
12 J9S RCA shield connection 32 ADCREF ADC reference voltage
13 J10P Audio tip connection 33 ADCIN+ ADC input +
14 J10S Audio ring connections 34 ADCIN - ADC input ­15 DACOUTA DAC channel A output 35 J7P Audio tip connection
16 DACOUTB DAC channel B output 36 J7S Audio ring connections
17 DACREF DAC reference voltage 37 J6P RCA center connection
18 GND System ground 38 J6S RCA shield connection
19 OP2AI+ Op-amp 2A input + 39 J5P BNC post connection
20 OP2AI- Op-amp 2A input - 40 J5S BNC shield connection

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