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PCF-8
Keithley MetraByte Corporation
The
PCF-8
Guide to Using
PASCAL, C, & FORTRAN
Callable Driver Software
for the
DAS-8, DAS=8PGA, & DAS-8/AO
Revision B, - July 1990
Copyright @ Keithley MetraByte Corp. 1989
Part Number: 24871
IGXTHIXY METRARYTFt CORPORATION
440 MYLES STANDISH BLVD., Taunton, MA 02780
TEL. 508/880-3000, FAX 508/880-O 179
...
- tta -
Warranty Information
All products manufactured by Keithley MetraByte are warranted against defective materials
and worksmanship for a period of one year from the date of delivery to the original
purchaser. Any product that is found to be defective within the warranty period will, at the
option of Keith@ MetraByte, be repaired or replaced. This warranty does not apply to
products damaged by improper use.
Warning
Keithley MetraByte assumes no liability for damages
consequent to the use of this product. This product is not
designed with components of a level of reliability suitable
for use in life support or critical applications.
Disclaimer
Information furnished by Keithley MetraByte is believed to be accurate and reliable.
However, the Keithley MetraByte Corporation assumes no responsibility for the use of such
information nor for any infringements of patents or other rights of third parties that may
result from its use. No license is granted by implication or otherwise under any patent
rights of Keithley MetraByte Corporation.
Notes
Keithley MetraByte/Asyst/DAC is also referred to here-m as Keith& MefraEQte.
BasicTMis a trademark of Dartmouth College.
IBM@is a registered trademark of International Business Machines Corporation.
PC, XT, AT, PS/2, and Micro Channel Architecture@ (MCA)are trademarks of
International Business Machines Corporation.
Microsoft@ is a registered trademark of Microsoft Corporation.
Turbo C@ is a registered trademark of Borland International.
- iv -
Contents
CHAPTER 1 INTRODUCTION
1.1 General ..... l-l
1.2 PCF-8 implementation ..... l-l
1.3 Current DAS-8 Driver ..... l-l
CHAPTER 2 MODE DESCRIPTIONS
2.1 Overview ..... 2-1
2.2 MODE Types & Functions .. ... 2-l
4.3 MODE Descriptions ..... 2-2
2.3.1 MODE 0: Initialize . ... . 2-2
2.3.2 MODE 1: Set Channel Scan Limits (MUX Low & High) ... .. 2-2
2.3.3 MODE 2: Set Next Multiplexer Channel . .... 2-3
2.3.4 MODE 3: Read Current Multiplexer Channel ... .. 2-4
2.3.5 MODE 4: Single A/D Conversion & Increment Channel MUX . .... 2-4
2.3.6 MODE 5: Multiple Conversions On Trigger; Transfer Data To Array ..... 2-5
2.3.7 MODE 6: Enable Interrupt Handler ..... 2-7
2.3.8 MODE 7: Disable Interrupt Handler ..... 2-8
2.3.9 MODE 8: Multiple Conversions On Interrupt (Background) ..... 2-8
2.3.10 MODE 9: Data Transfer To BASIC Array ..... 2-l 0
2.3.11 MODE 10: Configure Timer/Counter .. ... 2-l 1
2.3.12 MODE 11: Load Timer Counter ..... 2-l 2
2.3.13 MODE 12: Read Timer/Counter . .... 2-13
2.3.14 MODE 13: Read Digital Inputs IPl-3 . .. .. 2-13
2.3.15 MODE 14: Write Digital Outputs OPl-4 ..... 2-14
2.3.16 MODE 15: Measure Frequency ..... 2-15
2.3.17 MODE 16: Measure Period Or Pulse Width ..... 2-16
2.3.18 MODE 17: Enable/Disable Channel Tag .... . 2-l 7
2.3.19 MODE 18: Multiple A/D Conversions Via Software Trigger ..... 2-18
2.3.20 MODE 19: Set DAS-8PGA (Programmable Gain Amplifier) ..... 2-19
2.3.21 MODE 20: Return Interrupt State/PGA Status ..... 2-19
2.3.22 MODE 21: "N" Conversions In "x" Channel Bursts ..... 2-20
2.3.23 MODE 22: Multiple A/D Conversions w/Interrupts Using EXP-16 .. ... 2-21
2.3.24 MODE 23: Output Data To DACs (DAS8/AO Only) .... . 2-22
2.3.25 MODE 24: Update DACs From Array On Interrupt (DASS/AO Only) . .... 2-22
CHAPTER 3 ERROR CODES
CHAPTER 4 PROGRAMMING EXAMPLES
4.1 Language Interfacing ... .. 4-1
4.2 Programming In PASCAL ..... 4-1
4.3 Programming In Turbo PASCAL ..... 4-2
4.4 Programming In C .. ... 4-4
4.5 Programming In Turbo C ..... 4-5
4.6 Programming In Fortran ..... 4-7
4.7 General Notes ..... 4-8
-v -
Chapter 1
INTRODUCTION
1 .l OVERVIEW
MetraByte's PCF-8 package is an aid for Pascal, C, and Fortran programmers who must develop data
acquisition and control routines for MetraByte's DA!+8 series and EXP-16 (expander/multiplexer)
boards. The package consists of an Assembly language driver (DA%OBJ), a simple graphics package
(DRAW.LIB), and several example programs for each language.
Note that the DAS-8 series of boards includes the DAS-8, the DAS-SPGA, and the DAS-8/AO models.
For the sake of brevity, this manual refers to these boards collectively as the DAS-8/PGA/AO.
1.2 PCF-8 IMPLEMENTATION
The three software drivers supplied in the PCF-8 package are similar to the BASIC drivers provided
with the DAS8/PGA/AO and should therefore be easily implemented by anyone familiar with these
boards. If you are unfamiliar with MetraByte's DAS-8/PGA/AO, we suggest you read the manual for
these boards -- paying particular attention to the programming section (Chapters 3 and 4).
The differences between the PCF-8 callable drivers and those of the DAS-8 are the way data and
computer control are passed to and from the user program and the assembly driver. The various
functions are selected using MODES . Currently, there are 25 MODES (0 thru 24), each performing a
specific function. Each of these MODES is described in Chapter 4 of the DAS-8/PGA/AO manual,
which is extensively referenced herein. However, this manual includes a quick reference guide and a
description of each MODE along with applicable execution parameters. This document specifically
illustrates syntax and calling conventions required to execute any of the 25 MODES from Pascal, C,
and Fortran.
1.3 CURRENT DAS-8 DRIVER
The current DASS/PGA/AO driver is Version 4.4. This version is larger than its predecessors and
therefore uses more memory. It is important that machines have enough free memory when loading
the driver via BASIC.
l-l
Chapter 2
MODE DESCRIPTIONS
2.1 OVERVIEW
This chapter details the functions and implemention of each MODE. Arguments are integer variables.
Using QuickBASIC, a typical MODE passes and returns values as follows:
integer MD `Declare all variables as a-byte
integer D%(6) `signed/unsigned integers.
integer FLAG 'integer corresponding to error number.
MD%= mode number 'Range is 0 - 24
D%(0) = argument 1 `Set up arguments
D%(5) = argument 6
FLAG% = DAS8(MD%,D%) 'Flag returned from function
2.2 MODE TYPES & FUNCTIONS
MODE FUNCTIONALDESCRIPTION
0 Initialize DAS-8/PGA/AO (Set Base Address).
1 Set Channel Scan limits: DAS-8/PGA/AO MUXlow dz high.
2 Set next multiplexer channel.
3 Read current multiplexer channel.
4 Single A/D conversion, return data and increment channel.
5 Multiple A/D conversions. Scan rate set by Counter 2 or external strobe.
6 Enable DAS-8/PGA/AO interrupt handler.
7 Disable DAS8/PGA/AO interrupt handler.
8 Multiple A/D conversions on interrupts (Background operation).
9 Data transfer to BASIC array.
10 Configure DAS-8/PGA/AO timer/counter.
11 Load timer/counter.
12 Read timer/counter.
13 Read digital inputs lPl-3.
14 Write digital outputs OP1-4.
15 Measure frequency (with timer/counter).
16 Measure period (with timer/counter).
17 Enable/Disable Channel Tag (lower nybble).
18 Multiple A/D conversions using software trigger.
19 Set PGA gain @AS-8PGA only).
20 Return interrupt status.
21 Perform "N" A/D conversions in X channel bursts with triggers.
22 Multiple A/D conversions w/interrupts using EXP-16.
23 Output Data To DACs @AS-8/AO Only).
24 Update DACs from Array On Interrupt (DAS-8/AO Only).
2-1
PCF-8 Package
2.3 MODE DESCRIPTIONS
2.3.1 MODE 0: Initialize
Prior to using other MODES in the CALL routine, you must set the BASE ADDRESS and check for the
PGA or /A0 options. Failure to provide this information causes an error flag (FLAG = 1, Base
Address unknown) when other MODES are implemented. Intialization is required only once and is
generally accomplished in the initialization section of your program.
On entry the following parameters should be initialized:
MD% = 0 (MODE #I
BASADR% &H300
= (I/O address)
FLAG% = X (value does not matter)
Then
CALL DAS8 (MD%, BASADR%, FLAG%)
Alternatively, you may use DAS8DI.SYS (if previously installed, see Section 2.1) as follows:
MD%= 0 (MODE0)
BRDIDB = 0, 1, 2, 3, 4, or 5 (ID# for selected pCDAS-8PGA)
FLAG% = X (Value does not matter)
Then
CALL DAS8 (MD%, BRDID%, FLAG%)
On return, the variables contain data as follows:
MD% = 0 (unchanged)
BASADR% &H300
= (unchanged)
The following Error Codes apply to MODE 0:
If FLAG% = 0 (no error, OK)
= 2 (MODE number out of range, COor >24)
= 3 (Base Address out of range ~255 or ~1016)
Note that Error 3 occurs if you have specified an I/O address that is less than 255 (Hex FF) or greater
than 1016 (Hex 3F8). I/O addresses below Hex FF are used internally by devices on the IBM PC
system board and will always cause an address conflict with the DAS-S/PGA/AO. Addresses above
Hex 3FF are not decoded on the IBM PC.
2.3.2 MODE 1: Set Channel Scan Limits (MUX Low & High)
MODE 1 allows you to assign the channel scan limits prior to performing A/D conversions. The
lower and upper limits are passed as arguments in a 2-element array variable LT%(O) and LT%(l).
Default Channels are 0 and 7, respectively.
To illustrate the action of MODE 1, assume we set LT%(O) = 3 and LT%(l) = 6. The first A/D
conversion (via MODES 4 or 7) would be performed on Channel 3. Data is returned and the channel
incremented to 4. The next conversion is performed on Channel 4, data returned and the channel
2-2
CHAPTER 2 Mode Descriptions
incremented to 5, etc.. This continues until a conversion is performed on Channel 6. The multiplexer
address is then reset to 3 and the cycle may be repeated. Subsequent channel scanning occurs from
Channels 3 through 6. Continuous conversions on a single channel require the low and high channel
limits be set equal; for example LT%(O) = 1, LT%(l) = 1 (for Channel 1).
Note that the starting channel for A/D conversion defaults to LT%(O), the lower limit. If you wished
to start A/D conversion at some other channel, MODE 2 could be used to assign the starting channel #
after setting the channel scan limits.
On entry the following parameters should be initialized:
MD% = 1 (MODE #I
LT%(O) = Othru 7 (lower scan limit)
LT%(l) = Othru 7 (upper scan limit)
FLAG% =X (value does not matter)
Then
CALL DAS8 (MD%, LT%(O), FLAG%)
Specifying the first array element, LT%(O), will pass all other required array parameters.
On return the variables contain:
MO% = 1 (unchanged)
LT%(O) = Othru 7 (unchanged)
LT%(l) = Othru 7 (unchanged)
The following Error Codes apply to MODE 1:
IfFLAG% =O (noerror,OK)
=1 (Base Address unknown)
=2 (MODE number out of range, ~0 or >24)
=4 (scan limits out of range)
Error Code 4 indicates that either or both of the scan limits are out of range. That is, ~0 or >7 or their
order is reversed; for example, lower limit > upper limit.
2.3.3 MODE 2: Set Next Multiplexer Channel
MODE 2 sets the multiplexer address for the next conversion. Default is zero.
On entry the following parameters should be initialized:
MD% = 2 (MODE)
CH% = Othru 7 (channel number)
FLAG% = X (value does not matter)
Then
CALL DAS8 (MD%, CH%, FLAG%)
On return the variables contain data as follows:
2-3
PCF-8 Package
MD% = 2 (unchanged)
CH% = 0 thru 7 (unchanged)
The following Error Codes apply to MODE 2:
If FLAG% =0 (no error, OK)
= 1 (Base Address unknown)
=2 (MODE number out of range, COor 9.4)
=5 (channel number out of range)
Note that MODE 1 should be used to explicitly declare the channel scan limits prior to entering MODE
2. Otherwise, they will default to 0 and 7.
2.3.4 MODE 3: Read Current Multiplexer Channel
MODE 3 allows you to determine the current multiplexer (channel) address.
On entry the following parameters should be initialized:
MD% =3 (MODE)
CH% =x (value does not matter)
FLAG% =X (value does not matter)
Then
CALL DAS8 (MD%, CH%, FLAG%)
On return the variables contain data as follows:
MD% =3 (unchanged)
CH% = Othru 7 (current channel number)
The following Error Codes apply to MODE 3:
If FLAG% = 0 (no error, OK)
= 1 (Base Address unknown)
= 2 (MODE number out of range, COor ~24)
Note that attempting to read the MUX channel number while an A/D conversion is in progress may
have unexpected and generally undesirable effects. Therefore, when using the auto-increment
MODES 4,5 or 8, it is good practice to check the DAS-8/PGA/AO Status Register EOC bit for
inactivity (channel incrementing occurs at the start of the A/D conversion while the sample/hold is
holding and the EOC bit is active high).
2.3.5 MODE 4: Single A/D Conversion & Increment Channel MUX
MODE 4 initiates the following sequence of events:
1. Starts 12-bitA/D conversion,
2. Increments channel mux prior to A/D and sample/hold is holding. Checks scan limit; if limit
exceeded, reset to lower scan limit.
3. Poll status to determine if A/D finished.
2-4
CHAPTER 2 Mode Descriptions
4. Return data to variable.
The A/D performs conversions on channels in accordance with the conditions set in MODES 1 & 2. If
MODES 1 & 2 have not been entered prior to MODE 4, scan limits default to 0 & 7.
On entry the following parameters should be initialized:
MD% =4 (MODE)
D% =x (value does not matter)
FLAG% =x (value does not matter)
Then
CALL DAS8 (MD%, D%, FLAG%)
On return the variables contain data as follows:
MD% =4 (unchanged)
D% = data (converted data)
Note that if MODE 17 has been enabled prior to entering MODE 4, returned data will be "tagged' with
the channel address (see MODE 17).
The following Error Codes apply to MODE 4:
If FLAG% =0 (no error, OK)
=1 (Base Address unknown)
=2 (MODE number out of range, COor ~24)
=6 (A/D timeout)
Error Code 6 will occur only if the end of conversion signal (EOC) from the A/D remains high for
more than 100 microseconds or stays low after a conversion has been initiated. Either of these
conditions is indicative of a hardware fault and it is recommended that users replace the A/D
converter I.C. (AD574A) as a first step in attempting correction. A normal 12-bit A/D conversion
should not take more than 35 microseconds.
2.3.6 MODE 5: Multiple Conversions On Trigger; Transfer Data To Array
MODE 5 is an expanded version of MODE 4 for multiple data conversions according to the channel
scan limits. Mulitple conversions are initiated by a high input on IPl. Once the scan has started, the
rate at which conversions are performed is set by Counter 2. The number of conversions (N) specified
at entrance to the CALL is performed and data is transferred to a specified integer array ARRAY%(N)
previously dimensioned for not less than N elements. Error checking is not performed to determine
whether sufficient array space exists.
The interrupt handshake flip-flop on the DAS-8/PGA/AO is used to acknowledge trigger inputs in
this MODE although the conversions are not interrupt driven. MODE 5 performs a maximum of
about 4000 conversions/set; although some conversions may be delayed by the timer interrupt of the
IBM PC, since the system clock has a very high interrupt priority level. If you wish to trigger at a
programmable time interval set by Counter 2 then:
Jumper externally OUT 2 (Pin 6) to INT.IN (Pin 24)
Start scan High input to II'1 (Pin 25)
2-5
PCF-8 Package
See MODES 10 & 11 and Chapter 4 on setting Counter 2 to output a periodic pulse (configuration # 2
or 3). For slow scan rates ( ~27 milliseconds/conversion), counter 1 and/or 0 can be cascaded to
counter 2 output and their outputs connected to INTIN. Alternatively, you may connect an external
trigger source to lNT.IN, with each positive edge triggering a conversion. After the CALL routine is
entered, IPl is polled. If IF1 is low, polling will continue until it goes high. If IPl is an open circuit
(floats high) or as soon as it is driven high, the scan sequence commences on the first positive
transition to INTIN input. Each time a positive edge is received, an A/D conversion is performed as
in MODE 4.
The sequence of events is as follows:
1. Test IPl until it goes high.
2. Start A/D conversion on positive edge to INTIN
3. Clear interrupt flip-flop (IRQ) for next trigger.
4. Increment MUX after A/D has started and sample/hold is in hold. Check whether scan limit
exceeded; if so, reset to lower scan limit.
5. Poll status to determine if A/D finished.
6. Return data to next element of array.
7. Check for N conversions. If so, exit otherwise loop & do again.
The A/D will perform conversions on channels in accordance with the conditions set in MODES 1 or
2. If MODES 1 or 2 have not been entered prior to MODE 5, channel scan limits default to 0 & 7.
On entry the following parameters should be initialized:
MD% =5 WDE)
TRAN%(0) = VARPTR(ARRAY%(O)) (pointer to data array)
TRAN%(l) = N (number of conversions)
FLAG% =X (value does not matter)
IF TRAN%(O) = -1 THEN
TRW% (2) = OFFSET OF ARRAY
TRAN%(3) =SEGMF,NTOFARRAY
Then
CALL DAS8 (MD%, TRAN%(O), FLAG%)
On return the variables contain data as follows:
MD% = 5 (unchanged)
TRAN%(0) = VARPTR(ARRAY%(O)) (unchanged)
TFGiN%
(1) =N (unchanged)
ARRAY% (0) = Data from 1st. conversion
ARRAY%(l) = w I1 2nd. "
ARRAYO(2) = " 'I 3rd. "
ARRAY%(N-1) = Data from Nth. conversion
Note that if MODE 17 has been enabled prior to entering MODE 5, returned data will be "tagged" with
the channel number (see MODE 17). Also, exit from the routine will not occur until II'1 has been taken
high and TRAN%(O) is satisfied (desired number of conversions have been performed). If these
conditions are not met, your computer may appear to be hung waiting for the above conditions to be
2-6
CHAPTER 2 Mode Descriptions
satisfied. Control-Break will not exit you from the routine once started. Control-Alt-Delete will, but
your program will be lost. Be careful!
The following Error Codes apply to MODE 5:
If FLAG% =o (no error, OK)
=1 (Base Address unknown)
=2 (MODE number out of range, ~0 or >24)
=6 (A/D timeout on any conversion)
Error Code 6 occurs only if the end of conversion signal (EOC) from the A/D remains high for more
than 100 microseconds or stays low after a conversion has been initiated. Either of these conditions is
indicative of a hardware fault and it is recommended that users replace the A/D converter I.C.
(AD574A) as a first step in attempting correction. A normal 12-bit A/D conversion should not take
more than 35 microseconds.
2.3.7 MODE 6: Enable Interrupt Handler
MODE 6 sets up an interrupt service routine for subsequent background data transfer using MODE 8.
Before selecting MODE 6/8, you should decide upon the Interrupt Level you wish to assign to the
DAS-8/PGA/AO and position the Interrupt Level Jumper on the DAS-8/PGA/AO board (J2) to that
level. The IBM PC is provided with 8 levels of interrupts operating through the 8259 Interrupt
Controller. Level 0 has the highest priority and Level 7 the lowest. Levels 0 and 1 are not available on
the expansion bus connectors since Level 0 is used internally for the TIME & DATE functions, and
Level 1 is used to service the keyboard.
Levels 2 - 7 have been preassigned by IBM for use as follows:
Level 2 Reserved (but not used) by Color Graphics adapter
Level 3 Serial I/O - used by COM2: if installed.
Level 4 Serial I/O - used by COMl: if installed.
Level 5 Printer - may be used by LPT2: if installed.
Level 6 Always in use by disk drives
Level 7 Printer - may be used by LPTl : if installed.
Since the disk drives are slow devices, using interrupt levels lower than 5 might delay A/D
conversion service for long periods. In most systems, at least one or more of Levels 2 - 5 is available
making these the best choices. When you have decided, move the Interrupt Level Jumper on the DAS-
8/PGA/AO board to the desired Interrupt Level.
MODE 6 initiates the following sequence of events:
1. Loads interrupt vectors into memory for the level selected and stores any old vectors for
subsequent restitution by MODE 7.
2. Enables interrupt handler routine.
3. Initializes 8259 interrupt controller and enables 8259 interrupt mask register for level selected.
Interrupts are generated by a low to high transition on the INTIN input (Pin 24).
4. Specifies the type of interrupt buffer according to the "re-cycle" parameter. If D%(l)=O,
conversions cease after the buffer is filled. If D%(l)=l, the buffer is circular and begins
overwriting data upon buffer full. It makes sense to make the buffer a multiple of the number
of scanned channels. Buffer location and size are specified using MODE 8.
Interrupts are not enabled until the INTB bit in the DAS-8/PGA/AO control register is taken high.
MODE 8 performs this final step.
2-7
PCF-8 Package
On entry the following parameters should be initialized as follows:
MD% = 6 (MODE)
D%(0) = 2 thru 7 (interrupt level)
D%(1) = 0 or 1 (0 = NO Recycle, 1 = Recycle) )
FLAG% =x (value does not matter)
Then
CALL DAS8 (MD%, D%, FLAG%)
On return the variables contain data as follows:
MD% = 6 (unchanged)
D%(0) = 2 thru 7 (unchanged)
D%(1) = Recycle (unchanged)
The following Error Codes apply to MODE 6:
If FLAG% =0 (no error, OK)
=1 (Base Address unknown)
=2 (MODE number out of range, COor >24)
=7 (interrupt level out of range <2 or >7)
2.3.8 MODE 7: Disable Interrupt Handler
MODE 7 disables interrupt processing initiated by MODES 6 & 8 for the level previously selected. It
restores previous interrupt vectors and the 8259 mask register state. Note that the CALL routine
should not be reloaded before entering MODE 7 as this may destroy temporary storage of old vectors
etc.
On entry the following parameters should be initialized:
MD% = 7 (MODE#)
D% =x (declare variable, value does not matter)
FLAG% =x (entry value does not matter)
On return the variables contain data as follows:
MD% =7 (unchanged)
D% =x (unchanged)
The following Error Codes apply to MODE 7:
If FLAG% = 0 (no error, OK)
= 1 (Base Address unknown)
= 2 (MODE number out of range, 24)
2.3.9 MODE 8: Multiple Conversions On Interrupt (Background)
MODE 8 initiates background data acquisition via interrupts. MODE 8 requires two initialization
parameters; (1) the length of the data buffer (in words, 1 - 32767) and (2) the destination memory
segment for the data buffer. Each data word from the A/D requires 2 bytes, so that 32767 conversions
2-8
CHAPTER 2 Mode Descriptions
will occupy an entire memory segment (64K). Each conversion is triggered by an interrupt, and when
ready, data is transferred to the next available word in the buffer and the multiplexer incremented
within the scan limits in preparation for the next interrupt. Periodic interrupts can be derived from
the DAS8/PGA/AO timer/counter (set via 10) or alternatively by an external trigger input. An
external connection is required from the selected counter output or the user's trigger source to the
INT. IN (pin 24). Interrupts are triggered by a low to high transition at pin 24.
On entry, MODE 8 enables the INTE bit of the DAS-S/PGA/AO and the CALL is exited. As soon as
an interrupt is received, a conversion is performed and data transferred. This continues on each
interrupt until the data buffer is filled. If the recycle option of MODE 6 has been disabled, the INTE
bit of the DAS-8/PGA/AO control register is set to zero and futher interrupt inputs are ignored. If the
recycle option of MODE 6 is enabled, further conversions overwrite the data in the buffer, word by
word, starting from the beginning. In this case, the data buffer can be as small as 1 word or as large as
32767 words, but making the buffer a multiple of the number of active channels in the scan makes
every word correspond with a particular channel which is convenient for data retrieval. If the
interrupt is being derived from the DAS+J/l'GA/AO 8254 counter/timer, the counter gate can be
used to hold off interrupts until an external system is ready.
Each 12 bit conversion requires 2 bytes of memory for storage. Consecutive conversions are placed in
consecutive memory locations starting with the segment address specified. The segment address can
be in the range of 0 to -24577 (Hex 0 to 9FFF) * which corresponds to the maximum addressable
RAM available in the IBM PC. If MODE 17 is selected, the channel address is contained in the lower
nybble of the 1st byte. This "Tagged" data requires 2 bytes for storage (see MODE 17). In either case,
the 8 most significant bits of data are in the 2nd byte and the 4 least significant bits in the upper nybble
of the 1st byte.
Data is retrieved from memory to a BASIC integer array using MODE 9. You should choose a data
storage segment that will not interfere with your program space (that is, BASIC workspace or other
programs). If your machine is memory-limited, contraction of your BASIC workspace will be
required to open up a data storage area. Also avoid loading data over the CALL routine which
contains the interrupt handler. Once the interrupt is running, you may load other programs and other
languages and come back later to process collected data. If you do this, avoid resetting the computer
as the memory check that BIOS performs will destroy your data. The Ctrl-Alt-Delete sequence will
leave your data intact in memory but will discontinue interrupts.
NOTE: The DAS-8 driver adds the number of conversions to the segment address. If the
resultant segment address = > AOOOH,FLAG% = 8 is returned.
Apart from being a background operation, MODE 8 has a number of operational advantages from a
performance point of view. Data can be collected much faster than in MODES 4 & 5 as the execution
time of the BASIC interpreter involved in going in and out of the CALL statement is eliminated.
Secondly, a greater amount of data can be stored than is possible using a BASIC array since 64K
corresponds to the maximum workspace of BASIC including program, stack and temporary storage.
Therefore, considerably less than 64K of data storage is available in arrays within the BASIC
workspace. Provided you have sufficient memory, a full 64K block can be set aside for data storage.
Whenever maximum speed and/or maximum storage is required, MODE 8 should be used.
Up to 4000 conversions/set are possible using MODE 8. As the interrupt rate rises, less and less time
is available for foreground operations. Above about 3000 conversions/set a noticeable degradation in
computer processing speed will occur and certain I/O operations will become significantly slower.
2-9
PCF-8 Package
On entry, the following variables should be initialized:
MD% =8 NODE 1
D% (0) = 1 thru 32767 (data buffer length in words)
D%(1) = 0 thru -24577 (segment address of data storage)
FLAG% =x (entry value does not matter)
Then
CALL DAS8 (MD%, D%(O), FLAG%)
Note that D% must be a 2-clement integer array with only the first element referenced in the CALL.
On return all variables are unchanged except FLAG%.
MD% =8 (unchanged)
D%(0) = 1 thru -24577 (unchanged)
D%(1) = 0 thru 32767 (unchanged)
The following Error Codes apply to MODE 8:
If FLAG% =0 (no error, OK)
= 1 (Base Address unknown)
=2 (MODE number out of range, 32767 and/or the segment
address for storage is negative or ~32767 (AOOOH). In these cases, the interrupt will not be enabled.
2.3.10 MODE 9: Data Transfer To BASIC Array
MODE 9 transfers data from a memory storage area into a BASIC integer data array. MODE 9
transfers N conversions from offset M of the memory segment selected in MODE 8. MODE 9 can be
entered whether or not conversions in MODE 8 have ceased. MODE 9 simply copies data from
memory and will not alter the data. The number of conversions transferred (2 byte data words) can be
between 1 and 32767 and the offset can be anywhere from 0 to 32767. This allows transfer of any block
length of data from any location in data storage to an appropriately dimensioned integer array. This
indirect method of retrieving data may seem complex, but it avoids several problems that would arise
if data was transferred directly to an array by MODE 8. After entry to the CALL, the pointers to the
array are placed on the stack and used by the routine to locate the array. Once you have initiated
MODE 8 interrupt, it is possible to declare further simple variables, alter your program or chain to
other programs. Any of these actions would dynamically relocate the array variables so that CALL
would lose the location of the array with disasterous results. The solution is to reenter the CALL so
that it is always working with the current location of the array. This is why an indirect method is
used, giving you the flexibility to start the interrupt (MODE 8) with one program, then load another
program to read the data (MODE 9) and avoid disturbing the array location.
Once background data acquisition has been set up (via the recycle option of MODE 6 and a data buffer
area specified by MODE 8), a foreground program may be used to process data retrieved by MODE 9.
This is excellent for graphic and "digital oscilloscope" applications. The role of the variables is
somewhat different in MODE 9, and they should be initialized as follows:
2-10
CHAPTER 2 Mode Descriptions
ND% = 9 (MODE)
TRAN%(0) = VARPTR(ARRAY%(N)) (pointer to data array)
TRAN%(1) = 1 thru 32767 (number of data transfers)
TRAN%(2) = 0 thru 32767 (offset from segment start)
FLAG% =x (value does not matter)
TRAN%(O) points to the desired element in your data array (ARRAY%(N)) via VARPTR (N=O for
element 1). This array should be dimensioned for the maximum number of transfers specified in
TRAN%(l).
Then
CALL DAS8 (MD%, TRAN%(O), FLAG%)
On return the variables are as follows:
ND% = 9 (unchanged)
TRAN%(O - 2) (unchanged)
ARRAY%(N) = 1st data word
ARRAY%(N+l) = 2nd data word
AFtRAY%(N+2) = 3rd data word
The following Error Codes apply to MODE 9:
If FLAG% =0 (no error, OK)
=1 (Base Address unknown)
=2 (MODE number out of range, 24)
=9 (transfer parameters out of range)
Error 9 is returned if the number of data transfers requested is zero, negative or >32767 and/or the
memory offset is negative or >32767. Note that array size is not checked so that more data may be
transfered than the array can handle. This is often undesirable and may cause your computer to hang
UP*
It is reccommended that TRAN%(O) = VARFTR(ARRAY%(O)) be assigned immediately before the
CALL statement since declaration of a new simple variable after this assignment will dynamically
relocate ARRAY%(O) and upset operation of this MODE. For instance, the following example
correctly declares the variable "I" prior to the assigning TRAN%(O)=VARPTR(ARRAY(O)).
xxx10 I=3
xxx20 TRAN%(O) = VAW?TR(ARRAY%(O))
xxx30 CALL DAS8 (MD%, TM%(O), FLAG%)
As an alternative to MODE 9, you may be tempted to retrieve data using BASIC's PEEK function. If
interrupt transfers are active, be warned that PEEK retrieves data one byte at a time and interrupts
occuring between readings of low and high data bytes will cause the time sequential PEEK to return
erroneous data. Using MODE 9 avoids this problem.
2.3.11 MODE 10: Configure Timer/Counter
MODE 10 is used to configure the DAS8/PGA/AO timer/counter. For a complete discussion of the
possible configurations see Chapter 4 on timer/counter operations. Each of the three counters (0, 1 &
2) may be set to one of six configurations:
2- 11
PCF-8 Package
0 Pulse high on terminal count
1 Programmable one-shot
2 Rate generator
3 Square wave generator
4 Software triggered strobe
5 Hardware triggered strobe
On entry the following parameters should be initialized:
MD% = 10 (MODE)
D%(0) = Othru 2 (counter number)
D%(1) = Othru 5 (configuration number)
FLAG% =x (value does not matter)
Then
CALL DAS8 (MD%, D%(O), FLAG%)
On return the variables are unchanged:
MD% = 10 (unchanged)
D%(0) = 0 thru 2 (counter number)
D% (1) = 0 thru 5 (configuration number)
The following Error Codes apply to MODE 10:
If FLAG% = 0 (no error, OK)
= 1 (Base Address unknown)
= 2 (MODE number out of range, ~0 or >24)
= lO(counternumberoutofrange cOor >2)
= 11 (configuration number out of range 5)
2.3.12 MODE 11: Load Timer/Counter
MODE 11 loads the selected timer counter. Since each counter is a &bit device, counts as high as
65,535 are possible. Integer variables are signed N-bit words; that is, they can have values between -
32768 and +32767. To load a number above 32767, the integer data variable should be set to X - 65,536;
for example, 40,000 would be entered as -25,536.
On entry the following parameters should be initialized:
MD% = 11 (MODE)
D%(0) = 0 thru 2 (counter number)
D% (1) = -32768 to +32767 (counter load data)
FLAG% =X (value does not matter)
Then
CALL DAS8 (MD%, D%(O), FLAG%)
2-12
CHAPTER 2 M& Descriptions
On return the variables are unchanged:
MD% = 11 (unchanged)
D%(0) = Othru 2 (unchanged)
D%(1) = -32768 to +32767 (unchanged)
The following Error Codes apply to MODE 11:
If FLAG% = 0 (no error, OK)
= 1 (Base Address unknown)
= 2 (MODE number out of range, ~0 or >24)
= 10 (counter number out of range 2)
2.3.13 MODE 12: Read Timer/Counter
MODE 12 reads the selected timer/counter. Counter data is 16-bits wide and integer variables are
returned as signed %-bit words with values between -32768 and +32767. Numbers above 32767 are
returned as negative integers; for example, -8,000 would correspond to 65,536 - 8,000 = 57,536.
On entry the following parameters should be initialized:
MD% = 12 (MODE)
D%(0) = Othru 2 (counter number)
D%(l) = X (value does not matter)
FLAG% =x (value does not matter)
Then
CALL DAS8 (MD%, D%(O), FLAG%)
Variables are returned as follows:
MD% = 12 (unchanged)
D%(0) = Othru 2 (unchanged)
D%(1) = -32768 to +32767 (counter data)
The following Error Codes apply to MODE 12:
If FLAG% = 0 (no error, OK)
= 1 (Base Address unknown)
= 2 (MODE number out of range, ~0 or ~-24)
= 10 (counter number out of range 2)
2.3.14 MODE 13: Read Digital Inputs lpi-3
MODE 13 allows you to read the state of digital inputs IPl-3. Data returned can range between 0 and
7 corresponding to all combinations of the 3 input bits.
2-13
PCF-8 Package
On entry the following parameters should be initialized:
MD% = 13 WOW
IP% =x (value does not matter)
FLAG% =x (value does not matter)
Then
CALL DAS8 (MD%, IP%, FLAG%)
On return the variables contain data as follows:
MD% = 13 (unchanged)
IP% = 0 thru 7 (input data)
The following Error Codes apply to MODE 13:
If FLAG% = 0 (no error, OK)
= 1 (Base Address unknown)
= 2 (MODE number out of range, ~0 or >24)
2.3.15 MODE 14: Write Digital Outputs OPI-4
MODE 14 allows you to output data on the 4 digital output lines OP1-4. Since this data is passed
through the DASS/PGA/AO control register, MODE 14 performs an OR operation with the current
multiplexer address and INTB bits, leaving these unchanged.
On entry the following parameters should be initialized:
MD% = 14 (MODE)
OP% 0 thru 15 (output data)
FLAG% =x (value does not matter)
Then
CALL DAS8 (MD%, OP%, FLAG%)
On return the variables contain data as follows:
MD% = 14 (unchanged)
OP% = 0 thru 15 (unchanged)
The following Error Codes apply to MODE 14:
If FLAG% = 0 (no error, OK)
= 1 (Base Address unknown)
= 2 (MODE number out of range, COor >24)
= 12 (output data out of range, c0 or >15)
2-14
CHAPTER 2 Mode Descriptions
2.3.16 MODE 15: Measure Frequency
MODE 15 allows you to measure frequency using the 8254 counter/timer and one digital input. In
this MODE, Counter 2 is configured to output lmspulses. This square-wave output signal must be
externally connected to Counter 1 input. Setting FRQ%(O) = 100 provides a 1OOms gating pulse at the
output of Counter 1 (FRQ%(O) can be set to any number c 65,!?35mS). This output signal (counter 1)
must be externally connected to the gate of Counter 0 and IP2. The unknown frequency (a TTL
compatible signal) is connected to the clock input of Counter 0. During the low period of the gate
signal, Counter 0 is set to 65,535. When the gate signal goes high, Counter 0 counts down, and on the
gate signal returning low, the change in the count is returned in FRQ%(l). This count is proportional
to the frequency of the unknown signal and if gate intervals of 0.1, 1 or 10 seconds are used, the
unknown frequency is calculated by simply multiplying FRQ%(l) by 10,l or 0.1 respectively.
The following external connections should be made:
Jumper - Out 2 (Pin 6) to Clk.1 (Pin 4)
Jumper - Out 1 (Pin 5) to Gate 0 (Pin 21) and IP2 (Pin 26)
Unknown frequency (TTL) - wired to Clk.0 (Pin 2) and Common (Pin 11 or 28)
The DAS8 derives its timing from the system clock (of the computer) and is actually l/2 of the system
clock frequency. The DA!+8PGA has a dedicated 1 MHz clock. The DAS-8 contains a small rounding
error that occurs in Counter 2 (actual output pulses are 0.99985 mS period). An absolute accuracy of
+O.l% fl count is readily achievable.
MODE 15 sets the correct counter configurations and performs the entire frequency measurement
sequence once the external connections are made. Note that you may still use the output of Counter 1
to trigger interrupts and, in fact, this MODE sets the output of Counter 1 in convenient lms
increments. Note that the execution time of MODE 15 may be as much as 4*FRQ(O)mS. At higher
frequencies with 10 or 1OOms gating intervals, the measurement time is brief, but at low frequecies (for
example, 1,000 or 10,OOOmsgating intervals) measurement becomes quite slow. A faster and more
accurate method of measuring low frequencies ( c1OOHz.) is to measure the period using MODE 16
(next section) and derive the frequency from the reciprocal.
On entry the following parameters should be initialized:
MD% = 15 (MODE)
FRQ% (0) = 1000 (gating interval in mS, 10 - 32767)
FRQ% (1) = X (value does not matter)
FLAG% =x (value does not matter)
Then
CALL DAS8 (MD%, FRQ%(O), FLAG%)
On return the variables contain data as follows:
MD% = 15 (unchanged)
FRQ%(O)= 1000 (unchanged)
FRQ%(l)= data (count proportional to frequency)
The following Error Codes apply to MODE 15:
If FLAG% = 0 (no error, OK)
= 1 (Base Address unknown)
= 2 (MODE number out of range, COor >24)
2-15
PCF-8 Package
The frequency should be derived from the change in count returned by FRQ%(l) and the gating
interval l?RQ%(O) as follows:
xxxxx F=Q = FRQ% (1) * 1000 / FRQ%(O)
Note that a slightly more accurate result is obtained if account is taken of the real output interval of
Counter 2 (DAS-8 only ) which is 0.99985ms instead of lms. This correction error is small and can
usually be ignored, but for perfectionists, the correction can be included in the frequency calculation
above:
xxxxx FmQ = FRQ%(l) * 1000 / ( FRQ%(O) * 0.99985 )
DAS-8 only
2.3.17 MODE 16: Measure Period Or Pulse Width
MODE 16 measures Pulse Width by triggering Counter 2 (positive going edge from input signal) and
halting Counter 2 on the negative going edge. This results in determination of the half period of any
repetitive waveform or the duration of a positive pulse. DAS-8 timing is derived from the system
clock (2.38636 MHz, bus dependent) with each decrement being 0.41905 us while the DAS-8PGA
provides its own timing @ 1.000 MHz. Maximum period measurements are 27.46 ms (DAS8) and
65.54 ms (DAS8PGA). The signal for period or pulse duration measurement must be externally
connected to the gate input of Counter 2 (pin 23) and IP2 (pin 26). MODE 16 performs all the
necessary counter initialization and timing operations. Note that Counters 0 & 1 are not used and are
free for other operations.
On entry the following parameters should be initialized:
MD% = 16 (MODE)
PW% =x (value does not matter)
FLAG% =x (value does not matter)
Then
CALL DAS8 (MD%, PW%, FLAG%)
On return the variables contain data as follows:
MD% = 16 (unchanged)
PW% = -32768 thru 32767 (counts decremented)
The following Error Codes apply to MODE 16:
If FLAG% = 0 (no error, OK)
= 1 (Base Address unknown)
= 2 (MODE number out of range, 24)
Note that counts greater than 32767 will be returned as negative integers to and stored in 2's
complement form (see Appendix C).
2-16
CHAPTER 2 Mode Descriptions
The following short BASIC program returns a true count into a real variable (PULWID) and scales the
count to microseconds:
xxx10 IF PW%7)
Packing the channel number & data together maximizes memory and/or disk storage space. If
packed data is returned to an integer array (Z%/,),separation may be accomplished by isolating and
right justifying the EXP channel # (D&D3) as follows:
CHANNEL% (z%(I)
= AND &H7800)/2048
If data is negative, the sign must be moved to where the channel number was so that it immediately
precedes the data. This is accomplished as follows:
IF Z%(I) AND &Ii8000 THEN Z%(I) = (Z%(I) AND &H87FF) OR CH7800
Z%(I) is pure data and may be retrieved (see QBM22INT.BAS for usage).
2.3.19 MODE 18: Multiple A/D Conversions Via Software Trigger
MODE 18 is an analog threshold trigger with a user-efinable setpoint (per channel). As such,
triggering is controlled by software (comparison of input signal to threshold value). Once this
threshold is exceeded, "N" A/D conversions occur.
On entry the following parameters should be initialized:
MO% = 18 (MODE#I
D%(0) = Segment address of ARRAY* (Offset of 0 is assumed)
D%(1) = Number of conversions (Max number is 32768)
D% (2) = Trigger channel (O-7 independent of MUX Range)
D%(3) = Center of trigger window (O-4095 or t/-2047: Uni-Bipolar)
D%(4) = Upper/lower limit (o-2047)
D%(5) = Trigger slope (0 positive, 1 negative)
*
FORTRAN, PASCAL, C, and TurboBASIC pass the ARRAY Segment address as D%(O) =
VARSEG(ARRAY %(O))
whereas, GW BASIC and QuickBASIC pass the Segment address as D %(0) =
VARPTR(ARRAY %(O))
NOTE The trigger boundary defines a region +/- the trigger level. For a valid trigger to occur
the signal must pass through this region with the correct slope.
FLAG may return the following Errors:
If FLAG% = 0 No errors.
= 1 Base address unknown.
= 6 A/D time out.
= 13 Trigger channel out of range.
= 14 Trigger level out of range.
= 15 Invalid slope value.
2-18
CHAPTER 2 Mode Descriptions
NOTE: Error 6 indicates a hardware fault (See MODE 4).
2.3.20 MODE 19: Set DAS-8PGA (Programmable Gain Amplifier)
MODE 19 configures the PGA for input range and UNIPOLAR or BIPOLAR operation. The default
range is k5 Volts. The PGA option is configured as follows:
RANGE (VOLTS) GAIN CODE
+5 0
+10 8
OtolO 9
HI.5 10
Otol 11
f0.05 12
otoo.l 13
*0.01 14
0 to 0.02 15
On entry the following parameters should he initialized:
MD% = 19 (MODE#)
D%(0) = PGA (gain code given above)
FLAG may return the following Error Codes:
If FLAG% =o No errors.
=l Base address unknown.
=16 Invalid PGA gain code.
=17 Function unavailable (No DAS-8PGA)
2.3.21 MODE 20: Return Interrupt StatelPGA Status
MODE 20 is used for status determination of interrupt state (MODE 8) as well as for DAS-8PGA
determination (present or not).
On return, the variables contain:
MD% = 20
D%(0) = Interrupt status O=done, l=active.
D%(1) = Number of conversions done to this point.
D%(2) = Current channel number in DAS8-MUX.
D%(3) = PGA gain code (see above) , (-l=PGA not present) .
FLAG may return the following Error Codes:
If FLAG% = 0 No errors.
= 1 Baseaddress unknown.
2-19
PCF-8 Package
2.3.22 MODE 21: "N" Conversions In "X" Channel Bursts
MODE 21, converts "x" A/D channels on each interrupt generated by the DAS-8/PGA/AO. The
advantage of this MODE is that interchannel skew is small (420 us (n-tax) for eight channels on an IBM-
PC). Interchannel skew can be eliminated altogether by using MetraByte's SSH-4 (requires special
cable).
MODE 21 uses OUT-2 (Pin 6) to generate a square-wave frequency source. OUT-2 is tied to INT-IN
(Pin 24), IP-1 (Pin 25), and the sample/hold line of MetraByte's SSH-4 (optional). Each interrupt is
triggered by the rising edge of OUT-2 (this directs an SSH-4 to sample data). Once interrupted, the
software waits for the falling edge of OUT-2, by polling IP-1, triggering A/D conversions. This
ensures an SSH-4 is holding data. MODE 1 CALL (assign "X" channels) should precede a MODE 21
CALL in order to set up the channels to be scanned.
To control the start of data collection two optional triggers are provided. A hardware trigger, II?-2
(Pin 26), will be polled until it goes high. A software trigger, like MODE 18's, is also provided.
To run this MODE correctly requires three calls to MODE 21. The first call sets up the address of the
data array. The call is set up as follows:
MD% = 21 (MODE#)
D%(O) = 0 (Setup data array)
D%(1) = WLRPTR(A%(O))~ (BASICA's PTR to data array)
D%(2) = # of array elements corresponding to the # of conversions
D%(3) = DAS-8PGA 2 thru 72 (Interrupt level)
The second call initiates the interrupt and enables the optional software/hardware triggers. The call is
set up as follows:
MD% = 21 (MODE#)
D%(O) = 1 (Start data taking with triggers)
D%(l) = 0 (no software trigger)
E 1 (trigger on positive slope)
= 2 (trigger on negative slope)
If D%(l) isn't 0 then D%(24) contains additional software trigger information
D%(2) = Trigger channel (0 - 7)
D% (3) = Trigger level (+/- 2047 Bipolar)
(0 to 4095 Unipolar)
D% (4) = Trigger boundary (0 to 2047)3
D% (5) = 0 disables IP-2 trigger
To complete the conversion, the user must perform additional calls to MODE 21 with D%(O)=2. On
return from this call, D%(3) contains the number of conversions performed. The user must call this
MODE until D%(3) returns the total number of conversions requested. The call is set up as follows:
MD% = 21 (MODE#)
D%(O) = 2 (Monitor conversions)
D%(l) = 1 (to terminate MODE21 immediately)
D%(2) = 0
On return:
D% (3) = Number of conversions done
2-20
CHAPTER 2 Mode Descriptions
Possible return errors in FLAG%
0 (No errors)
1 (Base address unknown)
7 (Interrupt out of range)
13 (Trigger channel out of range)
14 (Trigger level out of range)
15 (Invalid slope value)
19 (MODE 21 D%(O) out of range O-2)
1 Note: FORTRAN, C, PASCAL, & TurboBASIC pass the ARRAY segment address as D%(O) =
VARSEG(ARRAY %(O))
whereas, GW BASIC & QuickBASIC pass the segment address as D%(O) =
VARPTR(ARRAY % (0))
2 On the UCDAS&PGA the interrupt level isn't required. It is derived directly from the boards
registers.
3 The trigger boundary defines a region +/- the trigger level. For a valid trigger to occur the signal
must pass through this region with the correct slope.
2.3.23 MODE 22: Multiple A/D Conversions With Interrupts Using EXP-16
MODE 22 is an interrupt driven data acquisition routine for use with one or more EXP-16s (8, max).
The interrupt level is set via MODE 6 and the interrupt itself may be generated by the DAS-
8/PGA/AO counter or by an external TTL, compatible signal. The scan limits on the DAS
8/PGA/AO must first be set using MODE 1. Upon interrupt, a single EXP-16 channel will be read for
each DAS8/PGA/AO channel within the scan limit. Upon channel scan completion, the EXP-16 will
be incremented for the next interrupt. Subsequent interrupts trigger the proces ◦ Jabse Service Manual Search 2024 ◦ Jabse Pravopis ◦ onTap.bg ◦ Other service manual resources online : Fixya ◦ eServiceinfo