BlueChip ADC-42 User manual

ADC-42
Digital and Analogue
Input/Output Module
User Manual

ADC-42
User Manual
Document Part N°0127-1014
Document Reference ADC-42\..\0127-1014.Doc
Document Issue Level 1.0
Manual covers PCBs identified ADC-42 Revision B
All rights reserved. No part of this publication may be reproduced, stored in any retrieval system, or
transmitted, in any form or by any means, electronic, mechanical, photocopied, recorded or otherwise,
without the prior permission, in writing, from the publisher. For permission in the UK contact Blue Chip
Technology.
Information offered in this manual is correct at the time of printing. Blue Chip Technology accepts no
responsibility for any inaccuracies. This information is subject to change without notice.
All trademarks and registered names acknowledged.
Blue Chip Technology Ltd.
Chowley Oak, Tattenhall
Chester, Cheshire
CH3 9EX.
Telephone : [phone] Facsimile : 01829 772001.

Amendment History
Issue
Level Issue Date Author Amendment Details
0.3 10.1.92 I.S First issue.
1.0 SEJ Window front cover and logo. See ECN
98/087

Contents
Blue Chip Technology Ltd. 01271014.doc
INTRODUCTION................................................................................1
1.0 SPECIFICATION..........................................................................1
1.1 Electrical Specification............................................................1
1.2 Physical Specification .............................................................2
Electromagnetic Compatibility (EMC).............................................2
EMC Specification .........................................................................3
2.0 USER ADJUSTMENTS................................................................4
2.1 Selecting the Base Address......................................................4
2.2 Port Map..................................................................................5
3.0 INPUT CONNECTIONS...............................................................6
Pin Detail.......................................................................................6
3.1 Pin Connections......................................................................7
4.0 USING THE ADC.........................................................................7
4.1 Analogue Inputs .......................................................................7
4.1.1 Analogue Input Options........................................................8
4.1.2 Example Program ...............................................................14
4.2 Analogue Outputs...................................................................15
4.3 Programmable Digital I/O......................................................16
4.4 Interrupts................................................................................21
APPENDIX A ...................................................................................24
APPENDIX B ...................................................................................26
PC/XT/AT Port Map .....................................................................26
APPENDIX C ...................................................................................28
PC/XT Interrupt Map....................................................................28
APPENDIX D ...................................................................................29
AT Interrupt Map..........................................................................29

Introduction
Blue Chip Technology Ltd. 01271014.doc
INTRODUCTION
The ADC card is a versatile 12 bit input and output subsystem, having both
analogue and digital capability.
The card can provide:
1. 24 Digital inputs or outputs.
2. 2 Channels of analogue output.
3. 16 Channels of single-ended analogue input.
or
8 Channels of differential analogue input.
4. Interrupt generator.

Specification Page 1
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1.0 SPECIFICATION
1.1 Electrical Specification
i. Analogue Input
Number of channels 16 Single Ended
or 8 Differential
Resolution 12 Bit
Conversion Time 10 Microseconds
Input Ranges (uni-polar) 0-5V or 0-10V
Input Ranges (bi-polar) +/-2.5V, +/-5V, +/-10V
(Link Selectable)
Maximum Input Voltage 12V
ii. Analogue Output.
Number of Channels 2
Resolution 12 Bit
Output Range 0-10V
Maximum Load Current 5mA DC
iii. Programmable Digital I/O
Number of Channels 24
High Logic Levels 2.4V to 5.5V
Low Logic Levels 0V to 0.8V
Max Sink Current (Output) 1.7mA @ 0.45V
Max Source Current (0 & 3) -200uA @ 2.4V
Max Source Current (1, 2 & 4, 5) -1mA @ 2.4V
iv. Power Requirement
Power Requirement 5V DC @ 300mA
+/-12V @ 50mA
Power Dissipation 2.25W

Page 2Specification
Page 2Blue Chip Technology Ltd. 01271014.doc
1.2 Physical Specification
Height 107mm
Width 15mm
Depth 132mm
Electromagnetic Compatibility (EMC)
This product meets the requirements of the European EMC Directive
(89/336/EEC) and is eligible to bear the CE mark.
It has been assessed operating in a Blue Chip Technology Icon industrial PC.
However, because the board can be installed in a variety of computers, certain
conditions have to be applied to ensure that the compatibility is maintained. It
meets the requirements for an industrial environment (Class A product) subject
to those conditions.
• The board must be installed in a computer system which provides screening
suitable for the industrial environment.
• Any recommendations made by the computer system manufacturer/supplier
must be complied with regarding earthing and the installation of boards.
• The board must be installed with the backplate securely screwed to the
chassis of the computer to ensure good metal-to-metal (i.e. earth) contact.
• Most EMC problems are caused by the external cabling to boards. Analogue
boards fitted with IDC ribbon cable connectors on the metal mounting
bracket require particularly careful installation of the external cabling. It is
imperative that any external cabling to the board is totally screened, and that
the screen of the cable connects to the metal end bracket of the board and
hence to earth. The cabling must be totally screened; the type of ribbon
cable which is rolled to a round form with a braided wire screen is best.
Standard ribbon cable will not be adequate unless it is contained wholly
within the cabinetry housing the industrial PC. Keep the unscreened section
as short as possible. The mounting bracket of the board includes a captive
nut as an screen earth point. Connect the screen of the cable to this by the
shortest possible wire.

Specification Page 3
Blue Chip Technology Ltd. 01271014.doc Page 3
• If difficulty with interference is experienced the cable should also be fitted
with a ferrite clamp as close as possible to the connector. The preferred type
is the Chomerics clip-on style, type H8FE-1004-AS.
• It is recommended that cables are kept as short as possible, particularly
when dealing with low level signals.
• Ensure that the screen of the external cable is bonded to a good RF earth at
the remote end of the cable.
Failure to observe these recommendations may invalidate the EMC compliance.
Warning
This is a Class A product. In a domestic environment this
product may cause radio interference in which case the user may
be required to take adequate measures.
EMC Specification
A Blue Chip Technology Icon industrial PC fitted with this card meets the
following specification:
Emissions: EN 55022:1995
Radiated Class A
Conducted Class A & B
Immunity: EN 50082-1:1992 incorporating
Electrostatic Discharge IEC 801-2:1984
Performance Criteria B
Radio Frequency Susceptibility IEC 801-3:1984
Performance Criteria A
Fast Burst Transients IEC 801-4:1988
Performance Criteria B

Page 4User Adjustments
Page 4Blue Chip Technology Ltd. 01271014.doc
2.0 USER ADJUSTMENTS
2.1 Selecting the Base Address
The board may be located in any 62 pin slot in the PC motherboard but must be
set up to appear at a specified position (or ‘address’) in the port map. Available
positions are shown in the IBM-PC Technical Reference Guide. However, for
those who do not possess a copy of this document a good place is the location
normally allocated to the prototyping card as supplied by IBM. This address is
300 Hex or 768 decimal.
All Blue Chip Technology cards are preset to this address at the factory.
However, no two devices should be used while set to the same address since
contention will occur and neither board will work. If your machine contains a
card with a conflicting address then another reasonably safe address is 200 to
21F (Hex).
A set of links is provided on the board to set the base address of the board
within the IBM-PC port map. The address is in binary with the presence of a
link representing a 0 and the absence of a link representing a 1.
To set the base address to 768 decimal (300 Hex) set the following pattern on
the links as indicated:
Figure 1 - Selecting the Base Address
Note: View board with back panel on RHS. Top 6 Bits of port address on links.
40
10 20
LSB
200
80 100
MSB
More example addresses are shown in Appendix A. Note: No two cards must
occupy the same address.

User adjustments Page 5
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2.2 Port Map
The address which is set by this link is effectively the base address of the card.
The basic programs shown throughout this manual will ask for an input of the
base as you have set it on the link LKA.
All ports used by these programs are referenced to this base value. A list of
address offsets and the functions of the ports are shown below.
Base + 0 =ADC Bit 7 = Busy Flag (Read)
Base + 1 =ADC Result High Byte (Read)
Base + 2 =ADC Result Low Byte (Read) and Start Conversion (Read)
Base + 3 =DAC Update Output (Write)
Base + 4 =DAC ‘A’ Low Byte Load Register (Write)
Base + 5 =DAC ‘A’ High Byte Load Register (Write)
Base + 6 =DAC ’B’ Low Byte Load Register (Write)
Base + 7 =DAC ‘B’ High Byte Load Register (Write)
Base + 8 =Digital PIO Port A
Base + 9 =Digital PIO Port B
Base + 10 =Digital PIO Port C
Base + 11 =Digital PIO Control Register (Write)
Base + 12 =Analogue Multiplexer Channel Address (Write)
Base + 13 =Programmable Interrupt Source Control Register (Write)

Page 6Input Connections
Page 6Blue Chip Technology Ltd. 01271014.doc
3.0 INPUT CONNECTIONS
A 50 way insulation displacement connector (IDC) is provided on the PC rear
panel of the board for I/O channel signal connection. If access to individual
channels is required, a 50 way IDC ribbon cable may be used to connect the I/O
channels to a 50 way screw terminal block available from Blue Chip
Technology as part number ST-24. The pins are numbered as shown in the
following diagram.
When the connector is viewed from the back of the system odd numbered pins
are on the left and even numbered pins are on the right with pin 1 at the top of
the connector.
Pin Detail
Pin 1Ο Ο Pin 2
Pin 3Ο Ο Pin 4
.Ο Ο .
.Ο Ο .
. .
. .
. .
. .
. .
Pin 47 Pin 48
Pin 49 Pin 50
View with gold edge connectors downwards.

Input Connections Page 7
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3.1 Pin Connections
ADC Input 0 1 Ο Ο 2 ADC Input 8 (Diff. Chan. 0)
ADC Input 1 3 Ο Ο 4 ADC Input 9 (Diff. Chan. 1)
ADC Input 2 5 Ο Ο 6 ADC Input 10 (Diff. Chan. 2)
ADC Input 3 7 Ο Ο 8 ADC Input 11 (Diff. Chan. 3)
ADC Input 4 9 Ο Ο 10 ADC Input 12 (Diff. Chan. 4)
ADC Input 5 11 Ο Ο 12 ADC Input 13 (Diff. Chan. 5)
ADC Input 6 13 Ο Ο 14 ADC Input 14 (Diff. Chan. 6)
ADC Input 7 15 Ο Ο 16 ADC Input 15 (Diff. Chan. 7)
17 Ο Ο 18 Analogue GND
19 Ο Ο 20 Analogue GND
DAC B Output 21 Ο Ο 22 Analogue GND
DAC A Output 23 Ο Ο 24 Analogue GND
Digital I/O A0 25 Ο Ο 26 Digital I/O A1
Digital I/O A2 27 Ο Ο 28 Digital I/O A3
Digital I/O A4 29 Ο Ο 30 Digital I/O A5
Digital I/O A6 31 Ο Ο 32 Digital I/O A7
Digital I/O B0 33 Ο Ο 34 Digital I/O B1
Digital I/O B2 35 Ο Ο 36 Digital I/O B3
Digital I/O B4 37 Ο Ο 38 Digital I/O B5
Digital I/O B6 39 Ο Ο 40 Digital I/O B7
Digital I/O C0 41 Ο Ο 42 Digital I/O C1
Digital I/O C2 43 Ο Ο 44 Digital I/O C3
Digital I/O C4 45 Ο Ο 46 Digital I/O C5
Digital I/O C6 47 Ο Ο 48 Digital I/O C7
Digital GND 49 Ο Ο 50 Digital GND
Note: In differential mode odd pins 1-15 are -ve, even pins 2-16 are +ve.
4.0 USING THE ADC
4.1 Analogue Inputs
Four ports are used to control analogue data collection on the ADC card:
Base + 0 = ADC Bit 7 Busy Flag (Read)
Base + 1 = ADC Result High Byte (Read)
Base + 2 = ADC Result Low Byte and Automatic ADC Start
Conversion (Read)
Base + 12 = ADC Multiplexer Channel Select (Write)
A typical sequence of events to acquire data would be:

Page 8Input Connections
Page 8Blue Chip Technology Ltd. 01271014.doc
i. Write the require channel number (0-15) out to Base + 12.
ii. Start conversion by reading Base + 2 (the resultant data can be
discarded).
iii. Read Base + 0 until bit 7 goes high indicating end of
conversion. (In basic or other slow languages it is not
necessary to perform this step as conversion only takes 10
microseconds).
iv. Read Base + 1 for the 4 MSB of the high byte result. (This
MUST be read before the low byte otherwise another
conversion is triggered. The card automatically puts 0’s into
the 4 low bits).
v. Read Base + 2 for the low byte result.
vi. Combine the 8 and 4 bits to get the 12 bit result.
4.1.1 Analogue Input Options
The analogue input options on the ADC are as follows:
i. Input Mode - Single Ended/Differential.
ii. Differential Mode Termination.
iii. Input Range - 0-5, 0-10V.

Input Connections Page 9
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a Input Mode
When all the signals to be measured have a common connection to ground
which is suitable for connection to the computer zero volts, then the ADC
module may be used in the single ended mode to provide 16 signal inputs with
the common connection going to digital ground. When the signals to be
measured are not referenced ground it will be necessary to use the differential
input mode.
In this mode the input signals are subtracted by the circuitry on the board so
that the difference or differential signal is measured.
In this mode inputs are used in pairs so that for differential input 0, the positive
connection is made to pin2 (input 8) and the negative connection to pin 1 (input
0) and so on in pairs. In the differential mode only 8 input signal (pairs) can be
accommodated.
Signal ended or differential mode is selected by two links marked LKJ and LKH
on the ADC card.
The following link positions should be used to select the required mode.
For Differential Mode
LKH
SDSD

Page 10 Input Connections
Page 10 Blue Chip Technology Ltd. 01271014.doc
For Single Ended Mode
LKH
DS
b Differential Mode Termination
This section is only relevant if you are using the analogue inputs in differential
mode.
The ADC uses solid-state multiplexers. These devices will not operate properly
if either signal voltage input exceeds + or - 12 volts. These limits define the
common mode voltage range. The board has a differential input option and will
accept signals which are floating with respect to the computer system ground.
But these signals must still lie within the common mode voltage range (CMVR)
in order to obtain satisfactory operation. In some cases it may be necessary to
tie external signals to the computer ground via suitable resistors to hold them
within CMVR. Failure to do so may result in erratic readings or damage.
The board provides links (LKE and LKD) which may be used to pull the input
signals towards ground. The 1M resistor value generally proves satisfactory,
but lower values may be needed in electrically noisy environments.
In many cases external signals are related to mains ground and the computer is
also earthed so that signals automatically lie within CMVR.
However, in the case of the Amstrad PC1512 computer, there is no built-in
mains earth connection and it may be necessary to provide one in order to
obtain proper performance of the ADC board.
Whether the differential signals are terminated or not is selected by two links
marked LKE and LKD on the ADC card.

Input Connections Page
11
Blue Chip Technology Ltd. 01271014.doc Page 11
The following link positions should be used to select the required mode.
For Termination
LKD LKE
a b a b
For No Termination
LKD LKE
a b a b
c Input Range Selection - Uni-polar
The ADC can be set to give maximum resolution over 0-5V or 0-10V.
The input range is selected by link LKC. Uni-polar/bi-polar selection is
selected by LKF on the ADC card.

Page 12 Input Connections
Page 12 Blue Chip Technology Ltd. 01271014.doc
The following link positions should be used to select the required mode.
LKF
B
UUni-polar Selection
For 0-5V Input
LKC
2.5
10
5+10V Selection