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Counter/Timer Programming Guide for Keithley DriverLINX (from DOCS-850A13)
User manual
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Tektronix Counter/Timer Programming Guide for Keithley DriverLINX (from DOCS-850A13) User manual

DriverLINX
Information in this document is subject to change without notice. The software described is this document is furnished under a license agreement. The software may be used or copied only in accordance with the terms of the agreement.
This document may not, in whole or in part, be copied, photocopied, reproduced, translated or reduced to any electronic medium or machine readable form without prior written consent from Scientific Software Tools, Inc.
DriverLINX Counter/Timer Programming Guide Copyright 1997-2001, Scientific Software Tools, Inc. All rights reserved.
SST 08-0101-1
LabOBJX, DriverLINX, and SSTNET are registered trademarks and DriverLINX/VB is a trademark of Scientific Software Tools, Inc. Microsoft and Windows are registered trademarks and Visual C++ and Visual Basic are trademarks of Microsoft Corporation. Borland is a registered trademark and Borland C++ is a trademark of Borland International, Inc. All Keithley product names are trademarks or registered trademarks of Keithley Instruments, Inc. All other brand and product names are trademarks or registered trademarks of their respective companies.
Contents
Preface 7
Software License and Software Disclaimer of Warranty...........................................................7
About DriverLINX.....................................................................................................................9
About This Programming Guide................................................................................................9
Conventions Used in This Manual...........................................................................................11
Why Use a Counter/Timer Device Driver 13
Using Direct Hardware I/O......................................................................................................13
Advantages of Device Drivers.................................................................................................13
Introducing DriverLINX 15
About DriverLINX...................................................................................................................15
DriverLINX Hardware Model..................................................................................................15
DriverLINX Programming Model...........................................................................................16
Summary.................................................................................................................................. 18
DriverLINX Driver....................................................................................................15
Logical Devices.........................................................................................................15
Logical Subsystems...................................................................................................16
Logical Channels.......................................................................................................16
Logical Device Descriptors .......................................................................................17
Service Requests ........................................................................................................17
C/C++ Interface.........................................................................................................18
Control Interface........................................................................................................18
Counter/Timers and DriverLINX 19
Counter/Timer Hardware Description......................................................................................19
Intel 8254...................................................................................................................19
KPCI-3140 Counter/Timer Chip ...............................................................................20
Am9513.....................................................................................................................20
DriverLINX Counter/Timer Model..........................................................................................21
DriverLINX Task Model .........................................................................................................26
Hardware Sharing......................................................................................................26
Creating Tasks...........................................................................................................26
Monitoring and Stopping Tasks.................................................................................27
DriverLINX Events ...................................................................................................27
DriverLINX Operations.............................................................................................28
DriverLINX Modes ...................................................................................................29
Individual and Group Tasks.......................................................................................29
Mapping Logical Channels to Counter/Timer Hardware Channels.........................................29
Digital I/O Hardware ...............................................................................................................30
Mapping Logical Channels to Digital Hardware Channels......................................................31
Properties of Logical Channels..................................................................................31
Combining or Splitting Logical Channels .................................................................31
DriverLINX Counter/Timer User’s Guide Contents • 3
Implementation Notes................................................................................................33
Programming Counter/Timers with DriverLINX 35
DriverLINX Counter/Timer Operations...................................................................................35
DriverLINX Tasks for All Subsystems......................................................................36
DriverLINX Tasks for Counter/Timer Subsystem.....................................................36
Foreground Tasks ......................................................................................................37
Background Tasks......................................................................................................37
Group Tasks...............................................................................................................38
DriverLINX Tasks for Digital Subsystems................................................................38
Using DriverLINX’s Service Requests....................................................................................39
Properties Common to All Service Requests.............................................................39
Modes and Operations for Counter/Timers................................................................40
Using Events to Control Service Requests ................................................................41
Events for the Counter/Timer....................................................................................41
Specifying Counter/Timer Channels in a Service Request........................................42
Specifying Data Buffers in a Service Request...........................................................43
Interfacing to DriverLINX.......................................................................................................43
Opening and Closing a DriverLINX Device Driver.................................................................44
Selecting a DriverLINX Device Driver....................................................................................46
Displaying the Edit Service Request Dialog............................................................................47
Reporting a DriverLINX Error.................................................................................................48
Stopping A DriverLINX Task..................................................................................................49
Initializing the Device..............................................................................................................50
Initializing a Counter/Timer Subsystem...................................................................................51
Using Messages and Events.....................................................................................................52
Events for Foreground Tasks.....................................................................................53
Events for Background Tasks....................................................................................53
Counter Output.........................................................................................................................55
Status Polling a Counter/Timer................................................................................................56
Configuring a Counter/Timer Channel.....................................................................................57
Converting Between Counts and Time....................................................................................58
Using Background Tasks.........................................................................................................60
Using a Counter/Timer to Generate Clock Messages................................................60
Storing the Counter/Timer Value at Each Interrupt ...................................................61
Controlling Group Tasks..........................................................................................................63
Select Channels..........................................................................................................64
Polled Mode Groups..................................................................................................65
Interrupt Mode Groups ..............................................................................................67
Using Digital I/O Tasks ...........................................................................................................68
Reading or Writing a Single Digital Value................................................................68
Reading or Writing Specific Digital Bits...................................................................72
Rapidly Transferring a Block of Digital Data............................................................75
Using Task-Oriented Functions 79
DriverLINX’s Task-Oriented Functions..................................................................................79
Event Counting ................................................................................................................. ....... 79
Starting an Event Counter ..........................................................................................79
Specifying the Rate Event for Event Counting..........................................................80
Hardware Setup for Event Counting..........................................................................84
Event Counting Using C/C++ .................................................................................... 84
Event Counting Using Visual Basic...........................................................................85
Frequency Measurement..........................................................................................................85
Starting a Frequency Counter ....................................................................................86
4 • Contents DriverLINX Counter/Timer User’s Guide
Specifying the Rate Event for Frequency Measurements..........................................87
Hardware Setup for Frequency Measurement ...........................................................89
Frequency Measurement Using C/C++ .....................................................................90
Frequency Measurement Using Visual Basic............................................................91
Interval Measurement ........................................................................................................... ...92
Starting an Interval Counter.......................................................................................92
Specifying the Rate Event for Interval Measurements ..............................................93
Hardware Setup for Interval Measurements..............................................................94
Interval Measurement Using C/C++..........................................................................94
Interval Measurement Using Visual Basic ................................................................95
Period and Pulse Width Measurement.....................................................................................96
Starting an Period or Pulse Width Measurement.......................................................96
Specifying the Rate Event for Period and Pulse Width Measurements.....................97
Hardware Setup for Period and Pulse Width Measurements.....................................98
Period or Pulse Width Measurements Using C/C++.................................................99
Period or Pulse Width Measurement Using Visual Basic........................................100
Pulse and Strobe Generation..................................................................................................101
Starting Pulse and Strobe Generation......................................................................101
Specifying the Rate Event for Pulses and Strobes...................................................102
Hardware Setup for Pulses and Strobes...................................................................104
Pulse and Strobe Generation Using C/C++ .............................................................105
Pulse and Strobe Generation Using Visual Basic....................................................106
Frequency Generation............................................................................................................107
Starting Frequency Generation................................................................................107
Specifying the Rate Event for Frequency Generation..............................................107
Hardware Setup for Frequency Generation .............................................................110
Frequency Generation Using C/C++ .......................................................................111
Frequency Generation Using Visual Basic..............................................................112
Hardware Reference 113
8254 Operating Modes...........................................................................................................113
Operating Mode Descriptions..................................................................................114
KPCI-3140 Operating Modes................................................................................................116
Operating Mode Descriptions..................................................................................116
Am9513 Operating Modes.....................................................................................................117
Operating Mode Descriptions..................................................................................118
Glossary of Terms 127
Index 129
DriverLINX Counter/Timer User’s Guide Contents • 5
Preface
Software License and Software Disclaimer of Warranty
This is a legal document which is an agreement between you, the Licensee, and Scientific S oftware Tools, Inc. By opening this sealed diskette package, Licensee agrees to become bound by the terms of this Agreement, which include the Software License and Software Disclaimer of Warranty.
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Licensing Agreement
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copyright laws and international treaty provisions. Scientific Software Tools, Inc. authorizes the original purchas er only (Licensee) to either (a) make one copy of the software solely for backup or archival purposes, or (b) transfer the software to a single hard disk only. The written materials accompanying the software may not be duplicated or copied for any reason.
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take all reasonable steps to protect Scientific Software Tools’ software from theft, disclosure or use contrary to the terms of the License.
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DriverLINX Counter/Timer User’s Guide Preface • 7
Limited Warranty
Scientific Software Tools, Inc. warrants that the software will perform substantially in accordance with the written materials and that the program disk, instructional manuals and reference materials are free from defects in materials and workmanship under normal use for 90 days from the date of receipt. All express or implied warranties of the software and related materials are limited to 90 days.
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This agreement is governed by the laws of the Commonwealth of Pennsylvania.
8 • Preface DriverLINX Counter/Timer User’s Guide
About DriverLINX
Welcome to DriverLINX for Microsoft Windows, the high-performance real- time data-acquisition device drivers for Windo ws application development.
DriverLINX is a language- and hardware-independent application-programming
interface designed to support hardware manufacturers’ high-speed analog, digital, and counter/timer data-acquisition boards in Windows. DriverLINX is a multi-user and multitasking data-acquisition resource manager providing more than 100 services for foreground and background data acquisition tasks.
Included with your DriverLINX package are the following items:
• The DriverLINX DLLs and drivers supporting your data-acquisition
hardware
• Learn DriverLINX, an interactive learning and demonstration program
for DriverLINX that includes a Digital Storage Oscilloscope
• Source code for the sample programs
• The DriverLINX Application Programming Interface files for your
compiler
• DriverLINX On-line Help System
• DriverLINX 4.0 Installation and Configuration Guide
• DriverLINX Technical Reference Manual
• Supplemental Documentation on DriverLINX and your data acquisition
hardware
About This Programming Guide
The purpose of this manual is to help you quickly learn to program DriverLINX for counter/ti mer operat i ons with your hardware.
• For help installing and configuring your hardware and DriverLINX,
please see the hardware manuals that accompanied your board and the DriverLINX 4.0 Installation and Configuration Guide for your version of Windows.
• For more information on the DriverLINX API, please see the on-line
DriverLINX Technical Reference Manual.
• For additional help programming your board, please exa mine the
source code examples on the Distribution Disks.
This manual is divided into the following chapters: Why Use a Counter/Timer Device Driver Brief discussion of why modern operating systems require device drivers. Introducing DriverLINX Presents a quick overview of DriverLINX’s hardware and programming model. Counter/Timers and DriverLINX Describes how DriverLINX’s hardware model supports counter/timer boards.
DriverLINX Counter/Timer User’s Guide Preface • 9
Programming Counter/Timers with DriverLINX
Explains how to program counter/timer tasks.
Using Task-Oriented Functions
Describes counter/timer functions that DriverLINX defines with a task orientation rather than a hardware orientation.
Hardware Reference
Describes Intel 8254, KPCI-3140 and Am9513 operating modes and how they map onto the DriverLINX programming model.
10 • Preface DriverLINX Counter/Timer User’s Guide
Conventions Used in This Manual
The following notational conventions are used in this manual:
• A round bullet identifies itemized lists (•).
• Numbered lists indicate a step-by-step procedure.
• DriverLINX Application Programming Interface and Windows macro
and function names are set in bold when mentioned in the text.
• DriverLINX indicates the exported function name of the device driver
DLL while DriverLINX indicates the product as a whole.
• DriverLINX Application Programming Interface identifiers, menu
items, and Dialog Box names are italicized when mentioned in the text.
• Italics are used for emphasis.
• Source code and data structure examples are displayed in Courier
typeface and bounded by a box with a single line.
Code
• A box with a double line bound tables of information.
Tables
Concept
• Important concepts and notes are printed in the left margin.
DriverLINX Counter/Timer User’s Guide Preface • 11
Why Use a Counter/Timer Device Driver
Using Direct Hardware I/O
Most counter/timer devices are simple devices to program. For years most
application developers wrote directly to the I/O hardware using the CPU’s I/O instructions (inp and outp) or using Peek and Poke statements in Basic. This was simple, fast, and efficient and required a minimal learning curve.
Under Windows 3.x, C/C++ developers could use these same techniques for most ports despite Microsoft’s strong recommendation against doing so. Visual Basic programmers, however, found that Microsoft had removed all direct I/O statements from the language, but they quickly discovered they could replace the missing statements with calls to simple DLLs.
With the arrival of Windows NT, direct hardware I/O in user applicatio ns is not physically possible. Hardware I/O in DOS and Win16 apps may appear to execute, but the CPU never actually executes the I/O instructions. In Win32 apps hardware I/O instructions generate a “privileged instruction exception” and terminate the offending app.
To perform user-level I/O in Windows NT and future versions of Windows 95, the operating system requires that applications communicate with the hardware using a device driver. Modern device drivers are effectively trusted operating system extensions that have more privileges than ordinary user-mode applications, DLLs, and services.
Advantages of Device Drivers
Using device drivers to control hardware offers an application in a modern multitasking, multithreaded operating system several advantages and one major disadvantage. The application advantages of the device driver model are
• hardware-independent access to boards belonging to a class of devices,
• resource sharing of a single physical device among multiple
applications and/or threads,
DriverLINX Counter/Timer User’s Guide Why Use a Counter/Timer Device Driver • 13
• resource arbitration when multiple device users contend for the same
hardware resources, and
• system security either at the logical level of authorized device users or
at the physical level of preventing misuse of a device.
The main disadvantage of the device driver model is the extra overhead the system requires to communicate device requests between the application, the device driver, and the hardware. For device requests, such as acquiring a million data samples
in one request, the overhead is negligible, but for acquiring one sample using a million separate requests, the time penalty is significant. For this reason,
developers must often redesign the protocols and algorithms that worked well in a single-tasking OS, such as DOS, for use in a multitasking system, such as Windows NT.
14 • Why Use a Counter/Timer Device Driver DriverLINX Counter/Timer User’s Guide
Introducing DriverLINX
About DriverLINX
The DriverLINX Distribution Disks contain many sample programs for a variety of hardware devices. Many samples will not work with counter/timer devices.
Welcome to DriverLINX for Microsoft Windows. DriverLINX is a language and hardware-independent, high-performance, real-time, data-acquisition device driver for 16 and 32-bit Windows 3.x, Windows 95 and Windows NT. DriverLINX supports an abstract hardware model for generalized data-acquisition hardware that includes analog and digital I/O as well as counter/timer functions.
This chapter briefly surveys the DriverLINX hardware and programming model. The on-line DriverLINX Technical Reference Manual included with the DriverLINX package is the complete, board-independent specification for the abstract DriverLINX hardware model. Whether or not you are familiar with DriverLINX programming, this guide will ease your learning curve by focusing on just the counter/timer subsystem programming model.
DriverLINX Hardware Model
DriverLINX Driver
Each DriverLINX driver supports one or more models of a device series in a
manufacturer’s product line. You can control multiple products from different series by opening several DriverLINX drivers. You can program each product using different “Service Requests” for each overlapping data-acquisition task.
Logical Devices
A single DriverLINX driver can support multiple boards from its list of supported models. During configuration, you assign each physical device a Logical Device number that you use to identify a particular board to DriverLINX. At run time, applications can determine the manufacturer, model name, I/O address, and hardware resources of a Logical Device by consulting DriverLINX’s Logical Device Descriptor.
DriverLINX Counter/Timer User’s Guide Introducing DriverLINX • 15
Logical Subsystems
DriverLINX treats all data-acquisition devices uniformly as abstract hardware consisting of seven possibl e subsystems.
• DEVICE—the physical hardware considered as a whole.
• AI (Analog Input)—the A/D converters, multiplexers, and associated
hardware.
• AO (Analog Output)—the D/A converters and associated hardware.
• DI (Digital Input)—the digital input ports and associated hardware.
• DO (Digital Output)—the digital output ports and associated hardware.
• CT (Counter/Timer)—the counter/timer channels and associated
hardware.
DriverLINX’s Logical Device Descriptor contains properties specifying which Logical Subsystems are available for a particular device. Counter/timer boards always support the DEVICE and CT subsystems, and some boards support additional subsystems, such as DI and DO.
Logical Channels
The subsystems, except DEVICE, consist of one or more data channels known as Logical Channels. Usually a Logical Channel corresponds to one hardware channel, but, for some boards, DriverLINX may use multiple Logical Cha nnel numbers to access a group of hardware channels using different data widths. DriverLINX records the number of Logical Channels and their capabilities in the Logical Device Descriptor.
DriverLINX Programming Model
Programming DriverLINX for data-acquisition tasks differs from the approach you may have used previously. Most vendors’ data-acquisition packages consist of thick documents describing hundreds of hardware-specific calls to configure and program a data-acquisition board. DriverLINX, in contrast, uses a board-independent list of properties to specify the parameters for a data-acquisition t a sk.
All data-acquisition tasks in DriverLINX use the same, simple three-step protocol:
1. Decide how you want to acquire data.
2. Specify your task by setting the properties of an object or data structure known as the Service Request.
3. Pass the Service Request to DriverLINX, which sets up the hardware and acquires the data for you.
The power of the Service Request approach is that you use the same structure for all data-acquisition tasks on any supported hardware. Once you understand how to program one type of device, you can use that knowledge to program any other supported device.
To notify an application of the progress or error conditions detected during a data­acquisition task, DriverLINX sends the application a series of messages just as Windows sends messages to an application’s message loop. This feature allows an
16 • Introducing DriverLINX DriverLINX Counter/Timer User’s Guide
application to overlap data processing with data acquisition and easil y synchronize the two activities.
Most data-acquisition drivers manage a hardware board exclusively for one application. DriverLINX, however, manages the subsystems of a hardware board as a shared resource that multiple applications or threads can share. If your hardware board has the necessary features, DriverLINX supports running multiple, independent tasks concurrently on one board.
Logical Device Descriptors
DriverLINX does not require that applications reference or use the LDD to program data-acquisition tasks.
The on-line DriverLINX Technical Reference Manual defines the DriverLINX Specification for all data­acquisition boards.
Using DriverLINX for a specific board requires learning just the supported properties for the board.
For writing hardware-independe nt applications, you may need to know the hardware specifications of the board your program is controlling. DriverLINX ma kes this information available to your program with another device-independent data structure known as the Logical Device Descriptor (LDD). The LDD contains information about number and types of data channels on the board, the allowed operating modes and commands, and many other details. For more information, see the on-line DriverLINX Technical Reference Manual.
Service Requests
The most important DriverLINX concept to understand is the Service Request. This is the object, data structure, or form that you use to specify all data-acquisition tasks.
As much as is possible, DriverLINX treats all data-acquisition tasks as similar using the same concepts and properties to define each possible task.
The key to learning how to specify a Service Request is first learning the major groups of a Service Request, and then learning the properties for each group.
A Service Request consists of four major property groups:
• Request Group—specifies the target Logical Device and Logical
Subsystem of a task and the data-acquisition mode and operation to perform.
• Events Group—specifies how DriverLINX should time or pace data
acquisition, when DriverLINX should start acquisition, and when it should end.
• Select Group—specifies the Logical Channels to acquire and the
number and length of data buffers to acquire.
• Results Group—DriverLINX uses these properties to return result
codes and single data values.
You can fill out Service Requests either interactively using the Edit Service Request Property page in DriverLINX or programmatically by assigning values to the required properties in each group.
DriverLINX Counter/Timer User’s Guide Introducing DriverLINX • 17
Summary
C/C++ Interface
If you are using C/C++, the Service Request is a C data struc ture type definition. Create an instance of the data structure, set all fields to zero, and then assign the proper values to each needed property in the groups. After setting up the Service Request, pass the address of the Service Request to DriverLINX for execution. DriverLINX will report information about the task back to t he app lication using Windows messa ges.
Control Interface
If you are using the Visual Basic custom control (VBX) or ActiveX (OLE or OCX) version of DriverLINX, the Service Request is an instance of the control o bject on your form or dialog. Assign the proper values to the needed properties for your task. Then tell DriverLINX to execute the Service Request by calling the Refresh method for the control. DriverLINX will report information about the task back to the application using control events.
DriverLINX provides a hardware-independent, abstract model of data-acquisition hardware co nsisting of seven possible Logical Subsystems. Each Logica l Subsystem treats data-acquisition tasks as conceptually similar. Develo pers program data­acquisition tasks by setting up the proper ties in the Request, Event, and Select Groups of a Service Request.
The on-line DriverLINX Technical Reference Manual def ines the DriverLINX Specification for all data-acquisition boards. Using DriverLINX for a particular board requires learning the supported properties for the hardware.
18 • Introducing DriverLINX DriverLINX Counter/Timer User’s Guide
Counter/Timers and DriverLINX
Counter/Timer Hardware Description
Most counter/timer boards use either the Intel 8254 Programmable Interval Timer or the AMD Am9513 System Timing Controller. The Intel 8254 is a much simpler device than the Am9513 chip, and the 8254 has limited capabilities without external circuitry and connections. Most vendors use the 8254 for clock generation on data­acquisition devices, but, for stand-alone counter/timer devices, the y usually use the more complex Am9513 chip or proprietary chips as in the Keithley KPCI-3140 (and the compatible KPCI-3100 Series).
The DriverLINX Counter/Timer programming model supports diverse hardware using a common programming model. Although the programming model is common, developers should understand the inherent hardware differences among counter/timer chips if they need to write applications to support different counter/timers. The following sections present an overview of hardware features of these chips.
Intel 8254
The Intel 8254 provides three 16-bit timing channels per chip that support six pulse and frequency generation modes. The Intel 8254 is capable of simple event counting, rate and square wave generation, one-shot, and strobe applications.
The following table describes the six operation modes and variations of the Intel
8254 counter/timer chip. For a detailed description of these modes, see “8254 Operating Modes” on page 113.
Mode Description
0 Event counting 1 Hardware retriggerable one-shot 2 Rate generator 3 Square wave generator 4 Software triggered strobe 5 Retriggerable hardware triggered strobe
Table 1 Designations for 8254 Counter/Timer Modes
DriverLINX Counter/Timer User’s Guide Counter/Timers and DriverLINX • 19
Without external circuitry, however, the Intel 8254 does not support selectable clock sources, gating control, or output polarity. The effect of the gate input on counting is a function of the selected mode. The 8254 has no built-in frequency prescaler and only counts in binary.
For more information, see the Intel 8254 Programmable Interval Timer data sheet and your counter/timer hardware User’s Guide.
KPCI-3140 Counter/Timer Chip
The counter/timer chip in the Keithley KPCI-3140 and KPCI-3100 Series provides four 16-bit timing channels per chip that support 3 pulse and frequency generation modes. In addition, the chip has two 24-bit counters but the onl y counter/ti mer function they can perform is to pace interrupt mode tasks.
The following table describes the three operation modes of the KPCI-3140 counter/timer chip. For a detailed description of these modes, see “KPCI-3140 Operating Modes” on page 116.
Mode Description
0 Non-retriggerable One-shot 1 Retriggerable One-shot 2 Continuous Increment
Table 2 Designations for KPCI-3140 Counter/Timer Modes
Am9513
The Am9513 provides five 16-bit timing channels per chip that support 19 pulse and frequency generation modes. In addition, the Am9513 supports a variety of software options to electronically interconnect counter channels and to program outputs. The Am9513 allows software to select 16 counting sources and 5 output modes independent of the chip’s operating mode. This chip has five built-in frequency prescalers and can count in either binary or binary coded decimal (BCD) modes. When using the prescalers in binary mode, each counter channel has an effective dynamic range of 32-bits.
The following table describes the 19 operation modes of the Am9513 and AMD’s letter designation for each mode. For a detailed description of these modes, see “Am9513 Operating Modes” on page 117.
Mode Description
A Software triggered Strobe with no hardware gating B Software triggered Stro b e with level gating C Hardware triggered Stro b e D Rate Generator with no hardware gating E Rate Generator with level gating F Non-retriggerable One-Shot G Software triggered delayed Pulse one-shot H Software triggered delayed Pulse one-shot with hardware gating
20 • Counter/Timers and DriverLINX DriverLINX Counter/Timer User’s Guide
Mode Description
I Hardware triggered delayed Pulse strobe J Variable Duty Cycle rate generator with no hardware gating K Variable Duty Cycle rate generator with level gating L Hardware triggered delayed Pulse one-shot N Software triggered Strobe with level gating and hardware retriggering O Software triggered Strobe with edge gating and hardware retriggering Q Rate Generator with synchronization R Retriggerable One-Shot S Delayed Pulse one-shot with level-selected reloading V X Rate Generator with edge gating
Table 3 Letter Designations for Am9513 Counter/Timer Modes
Frequency -Shift Keying
Each Am9513 chip occupies 2 consecutive I/O addresses. The first location addresses a control port and the second a data port.
The Am9513 can be a complex chip to learn, program, and use because of its rich
feature set. For detailed hardware information, consult Advanced Micro Devices’ Am9513A/Am9513 System Timing Controller Technical Manual and your counter/timer hardware user’s guide.
DriverLINX Counter/Timer Model
Figure 1 DriverLINX Counter/Timer Model
DriverLINX abstracts all counter/timer hardware chips as an array of three terminal devices. The terminals of an individual counter/timer are
• Clock—the source input for dividing down to a lower frequency or for
counting external events.
• Gate—the control input for triggerin g, re-triggeri ng, or gating the
counter/timer operation.
• Output—the counter/timer output frequency, pulse, or stro be.
DriverLINX associates with each counter/timer channel four operating properties. The properties are
• Mode—defines the operational task for the counter/timer channel.
• Period—defines the cycle period or divisor for the counter/timer
channel.
DriverLINX Counter/Timer User’s Guide Counter/Timers and DriverLINX • 21
• OnCount—defines high duration of the period for asymmetrical output
trains or pulses.
• Pulses—defines the number of periods to generate.
22 • Counter/Timers and DriverLINX DriverLINX Counter/Timer User’s Guide
Capabilities of DriverLINX’s
f
counter/timer subsystem depend on the hardware
eatures of your board.
By selecting values for these seven properties and, where necessary, making the appropriate connections between counters, applications can program DriverLINX to
execute one of the counter/timer’s basic operating modes or the following counter/timer operations and tasks:
• Event counting—16-, 32-, and 64-bit counters for signals at the Clock
input.
• Frequency measurement—16- and 32-bit frequency measurement.
• Interval measurement—Measure time between two consecutive
pulses at a single input or two pulses at separate inputs.
• Period and pulse width measurement—Measure duration of each
cycle or half cycle.
• Pulse generation—Generate a variety of one-shot pulses and strobes.
• Frequency generation—Generate periodic pulse trains, variable duty
cycle waveforms, square waves, or input-modulated waveforms.
Applications may program and operate counter/timers independently, or they may configure the operating mode for several counter/timers and start or stop them synchronously. For hardware boards that support interrupts, applications may program a list of timers whose current value DriverLINX will read into a buffer on each interrupt.
The following tables show the legal values for the Clock, Gate, Output, and Mode fields of a DriverLINX logical counter channel. Note that the capabilities of the Intel 8254 are a subset of the Am9513’s capabilities.
Clocks
The Clock property specifies the source input for the abstract counter/timer of a Logical Channel.
Clock Description Intel 8254 KPCI-3140 Am9513
Internal1.. Internal5
Source1.. Source5
Gate1.. Gate5
External External clock frequency
ExternalPE External clock frequency
ExternalNE Ext ernal clock frequency
TCNm1 Use channel N-1 terminal
Table 4 Allowed Values for Rate Event Clock Property
Internal clock frequency prescaled at 1 of 5 taps
Use channel 1..5 source (clock) input
Use channel 1..5 gate input no no yes
(usually positive edge)
(positive edge clocking)
(negative edge clocking)
count output
yes (Internal1 only)
no no yes
yes yes yes
yes yes yes
no yes yes
no yes yes
yes (Internal1 only)
yes
DriverLINX Counter/Timer User’s Guide Counter/Timers and DriverLINX • 23
• For the Am9513-based counter/timers, you may also request that the
clock input use the negative-going edge of the clock input rather than the positive edge.
• Internal1 always designates the onboard hardware clock. Internal2..Internal5 designate lower frequency taps of the master clock if the hardware supports this capability.
• If the application uses an Internal1 clock with a Period value greater than the hardware counter/timer supports, DriverLINX will automatically select available hardware prescalers to obtain the closest value to the requested Period.
Gates
The Gate property selects how the abstract counter/timer uses the gate input of a Logical Channel. Generally, this input gates the counting or measuring process or triggers the counter/timer operation.
Gate Description Intel 8254 KPCI-3140 Am9513
Enabled Enable gate yes yes yes Disabled Enable gate no* yes yes NoConnect No connection modes 0,2-4 yes yes LoLevel
GateN LoEdge
GateN HiLevel
GateN HiLevel
GateNp1 HiLevel
GateNm1 HiTcNm1 Positive edge at terminal
HiEdge GateN
Logic low level at gate input N no mode 2 yes
Negative edge at gate input N no modes 0,1 yes
Logic high level at gate input N
Logic high level at gate input N+1
Logic high level at gate input N-1
count output N-1 Positive edge at gate input N modes 1,5 modes 0,1 yes
modes 0,2-4 mode 2 yes
no no yes
no no yes
no no yes
Table 5Allowed Values for Rate Event Gate Property
*Some boards provide off-chip hardware that can disable the 8254’s gate.
24 • Counter/Timers and DriverLINX DriverLINX Counter/Timer User’s Guide
Outputs
The Output property programs the polarity and duty cycle of the abstract
counter/timer’s output port.
Output Description Intel 8254 KPCI-3140 Am9513
Default Depends on operation (see
“Counter Output” on page
55) LoToggled Start low; toggle at TC yes yes yes LoActive Active low pulse at TC yes yes yes LoZ Inactive low impedance
output Toggled Toggle at TC yes no yes HiToggled S tart high; toggle at TC yes yes yes HiActive Active high pulse at TC no yes yes HiZ Inactive high impedance
output
Table 6 Allowed Values for Rate Event Output Property
DriverLINX automatically selects an output type if the application requests Default. Depending on hardware capabilities, DriverLINX chooses the output option based on the requested Mode. The Intel 8254 allows only one output mode, which depends on the operation.
yes yes yes
no no yes
no no yes
Modes
The Mode property selects the type of rate generator or task the abstract counter/timer will perform. Mode values fall into two gener a l gro ups—pulse and
wavefor m generators and measurement tasks. Note that the generator modes (e.g., RateGen, SqWave, etc.) program a single Logical Channel of an abstract counter/timer while the measurement modes (e.g., Frequency, Interval, etc.) may program multiple Logical Channels.
Generator Description Intel 8254 KPCI-3140 Am9513
RateGen Periodic rate generator yes yes yes SqWave Square wave generator yes yes yes VDCGen Variable duty cycle rate
generator BurstGen Burst rate generator no no no Divider Frequency divider no yes yes Freq Frequency counter yes yes yes Interval Interval timer yes no yes Count Event counter yes yes yes PulseWd Pulse width measurement yes yes yes SplitClk Split frequency rate
generator
yes yes yes
no no no
DriverLINX Counter/Timer User’s Guide Counter/Timers and DriverLINX • 25
Generator Description Intel 8254 KPCI-3140 Am9513
FskGen Frequency-shift keying no no yes PulseGen Pulse generator no yes yes Retrig
RateGen Retrig
SqWave Count32 32-bit event counter no yes yes Count64 64-bit event counter no yes yes Freq32 32-bit frequency counter no yes yes FreqRatio Frequency ratio counter no no no OneShot One-shot pulse or strobe yes yes yes Retrig
OneShot
Table 7 Allowed Values for Rate Event Mode Property
Retriggerable rate generator no no yes
Retriggerable square wave generator
Retriggerable one-shot pulse or strobe
no no yes
yes no yes
• Some of the above mode field options, e.g., BurstGen, specify features
that require external connections, which some vendors have prewired into their products.
• Other options, such as frequency measurement modes, require external
user connections between counter/timer terminals.
DriverLINX Task Model
To manage a user application’s data-acquisition requests, DriverLINX creates tasks. A DriverLINX task consists of the set of hardware and system resources and the board-specific protocols required to execute the data-acquisition request. Applications can start tasks, monitor tasks, and stop tasks by submitting Service Requests to DriverLINX.
Hardware Sharing
DriverLINX allows multiple applications to share a data-acquisition device or allows multiple tasks to run on a device if the hardware can support concurrent operations. To support hardware sharing and concurrency, DriverLINX assigns resources to each task and then compares the resource requirements of a new task with the in-use resources of all current tasks. If the new requirements do not conflict with the current in-use resources, DriverLINX updates the in-use resources and starts the task. Otherwise, DriverLINX rejects the newly requested task.
Creating Tasks
User applications create data-acquisition tasks by setting the properties of a Service Request to values that specify the task. Then the application submits the Service Request to DriverLINX, which transforms each Service Request into a procedure for performing the task on the requested hardware subsystem. To execute a new task, DriverLINX performs the following steps for each Service Request:
26 • Counter/Timers and DriverLINX DriverLINX Counter/Timer User’s Guide
A Start operation fills in the
Applications may also check the status of a task or terminate a task by modifying the
taskId property. DriverLINX uses the taskId to determine to which task a Status or Stop operation applies.
1. Audit the Service Request fields to determine if the hardware can perform the task.
2. Request necessary hardware and system resources to perform task.
3. Con vert the Service Request into the hardware parameters and protocols to perform the task.
4. Execute the task on the hardware.
5. Notify application of any requested task events as they occur.
6. Wait for the task to complete.
7. Release requested hardware and system resource used by the task.
If DriverLINX detects any errors in the Service Request or in the hardware during the task, it aborts the task and returns an error code to the application. If the application requests hardware resources that are already in use by another thread or process, DriverLINX also stops the task and notifies the application.
Monitoring and Stopping Tasks
operation property of the Service Request used to create the task and resubmitting it
to DriverLINX. To check status, change the operation property to “status”. To terminate a task, change the operation property to “stop”.
DriverLINX Events
Applications can request that DriverLINX notify the application of significant events during execution of a task. By designing a data-acquisition task to use events, an application can overlap data processing with data collection. Events allow the application to coordinate these two activities without t he overhead associated with polling for the status of the data collection task and without the scheduling pr oblem of coordinating data processing with partial data collection.
DriverLINX posts events to an application through t he Windows messaging mechanism. DriverLINX supports the following messages:
Message Description Posted
ServiceStart Task is starting Default. Can disable. ServiceDone Task is complete Default. Can disable. BufferFilled Buffer processing complete Can enable. DataLost Data over/underrun Always reported. TimerTic Timer interrupt occurred Non-buffered CT task. StartEvent Start event detected Can enable. StopEvent Stop event detected Can enable. CriticalError Hardware error Always reported.
Table 8 DriverLINX Messages
DriverLINX Counter/Timer User’s Guide Counter/Timers and DriverLINX • 27
The most useful events for applications are ServiceDone, BufferFilled, and DataLost.
• The ServiceDone event notifies the application that DriverLINX
terminated the task. Tasks may end because the application stopped it, the stop event condition in a Service Request was satisfied, or DriverLINX detected a run-time error and stopped the task.
• The BufferFilled event notifies the application that DriverLINX has
read or written the current buffer. Applications can use this message with multiple data buffers to eliminate polling the driver for the status of the task and to overlap data processing with data acquisition.
• The DataLost event notifies the application that DriverLINX detected
that the hardware was filling or emptying buffers faster than the application or driver could process the buffers.
The other DriverLINX events are useful for special cases.
• The ServiceStart event notifies the application that DriverLINX is
starting the task. An application might use this event to provid e visual feedback to the user interface that the task is starting.
• The TimerTic event notifies the application that DriverLINX has
processed a clock interrupt. DriverLINX only reports this event for the counter/timer subsystem when the task is not using data buffers.
• The StartEvent notifies the application that DriverLINX detected that
the logical condition the application specified in the Service Request’ s Start Event is true. DriverLINX can only report this event if the hardware generates an interrupt associated with the Start Event.
• The StopEvent notifies the application that DriverLINX detected that
the logical condition the application specified in the Service Request’ s Stop Event is true. DriverLINX can only report this event if the hardware generates an interrupt associated with the Stop Event.
• The CriticalError event notifies the application that DriverLINX
detected an unexpected critical error other than DataLost. This usually indicates either the hardware or software is malfunctioning and needs repair or re-configuration.
DriverLINX Operations
For most counter/timer hardware, applications can select one of five operations for a task. The basic counter/timer task operations are
• Initialize—resets the counter/timer subsystem software and/or
hardware.
• Configure—set up a counter/timer for a task, but do not start the task.
• Start—set up and arm a counter/timer for a task. The Gate, Clock, and
Mode properties determine when the hardware starts counting.
• Status—return the current counter/timer count value and status to the
application.
• Stop—disarm the counter/timer task and make the task resources
available for new tasks.
The Initialize, Configure, and Start operations all create a DriverLINX task. The task that DriverLINX creates for the first two operations exists only briefly during the
28 • Counter/Timers and DriverLINX DriverLINX Counter/Timer User’s Guide
application’s function call to DriverLINX. For a Start operation, however,
operation to read the current count value of a counter/timer. The counter/timer
DriverLINX creates a task that may exist indefinitely until the application explicitly ends the task with a Stop operation or DriverLINX ends the task because the Stop Event has become true.
DriverLINX Modes
For most counter/timer hardware, DriverLINX supports three task modes, OTHER, POLLED and INTERRUPT.
• When an application uses OTHER mode, DriverLINX initializes the subsystem or configures a Logical Channel without starting the counter.
• When an application uses POLLED mode, DriverLINX starts the counter/timer hardware running, but it does not automatically report any status information about the task to the application.
• When an application uses INTERRUPT mode, DriverLINX starts the counter/timer hardware running with a hard wa re interrupt enabled. At each interrupt, DriverLINX either sends a TimerTic event to the application or saves the current count of the requested counter/timers into a data buffer.
For other subsystems, polled mode tasks start and stop before DriverLINX returns control to the application.
When using polled mode counter/timer operations, DriverLINX return s control to the application after starting the counter/timer hardware. Applications must use the
Status
task will run until the application ends it with a Stop operation. When using interrupt mode counter/timer operations, DriverLINX also returns
control to the application after starting the counter/timer hardware. However, if the application specified data buffers in the Service Request, DriverLINX will automatically read and store the current counter value(s) into the buffer. The application may request that DriverLINX read the next Logical Cha nnel in the Channel list at each interrupt or that DriverLINX read all Logical Channels at each interrupt. If the application is not using buffers, then DriverLINX sends a TimerTic event to the application at each interrupt.
Individual and Group Tasks
Applications can control individual counter/timer channels as separate task s or they can synchronize the starting and stopping of multiple channels. To collect multiple channels into a group, the application first performs Configure operations on each channel in the group to set up the hardware. Then the application can start the channels in the group by executing a Service Request with a Start operation that lists the group’s channels in the Service Request’s channel list. By using a Stop operation instead, the application can simultaneously stop all channels in the group. For more information, see “Group Tasks” on page 38.
Mapping Logical Channels to Counter/Timer Hardware Channels
DriverLINX maps the hardware’s counter/timer channels to consecutive Logical Channels. The following table shows the correspondence between the hardware channels and Logical Channels. Note that DriverLINX always uses zero-based
DriverLINX Counter/Timer User’s Guide Counter/Timers and DriverLINX • 29
numbering for Logical Channels while vendors often use one-based channel numbering.
Logical Channel
CTM-05 1 2 3 4 5 CTM-05A 1 2 3 4 5 CTM-10 1A 2A 3A 4A 5A 1B 2B 3B 4B 5B
Table 9 Map of Logical Channels to Counter/Timer Hardware Channels
For other models, see the appropriate Using DriverLINX with your Hardware manual.
Digital I/O Hardware
0 1 2 3 4 5 6 7 8 9
Software cannot read or control the strobe lines for digital inputs without external connections.
The MetraByte counter/timer boards support one or more digital I/O ports. The CTM-05/A board has one 8-bit digital input port with latch and one 8-bit digital output port with latch. The CTM-10 board has two 8-bit digital input ports with latches and two 8-bit digital output ports with latc hes. A strobe line input at each input port controls whether the input data passes through the latch or is held by the latch. There is no software control over this strobe line. For more infor mation, see the CTM-10 and CTM-05/A User’s Guide.
These digital ports are physically independent of the counter/timers and do not have any internal connections to the counter/timers. Also, the digital I/O ports do not generate any hardware interrupts. Applications can read or write the digital ports independently of the counter/timers. DriverLINX does support reading a digital input port at each counter/timer interrupt to start or stop a counter/timer task.
The CTM Ser ies boards also have a digital input line that generates a hardware interrupt. DriverLINX models this line as a special-purpose, 1-bit digital input channel. Associated with the interrupt input line is another external input line t hat enables or disables the interrupt input line. DriverLINX has no direct hardware control over this gating line.
For other models, see the appropriate Using DriverLINX with your Hardware manual for details on digital I/O features.
30 • Counter/Timers and DriverLINX DriverLINX Counter/Timer User’s Guide
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