National Instruments PC-LPM-16/PnP - page 103

Appendix D Register-Level Programming

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National Instruments Corporation D-31 PC-LPM-16/PnP User Manual

after getting the required number of conversions. The number of

conversions in a single data acquisition operation in this case is

unlimited. Counter 0 is clocked by a 1 MHz clock upon start up.

Each of these programming steps is explained as follows.

1. Select the Analog Input Channel.

Write to Command Register 1 to select the analog input channel.

The SCANEN* bit must be set for data acquisition operations on a

single channel. See the Command Register 1 bit descriptions earlier

in this appendix for analog input channel bit patterns.

Write to Command Register 1 only when the analog input channel,

scanning mode, or interrupt mode needs to be changed.

To enable the data acquisition operation, clear the CALEN bit of

Command Register 2.

2. Program the Sample-Interval Counter (counter 0).

Counter 0 of the MSM82C53 counter/timer is used as the sample-

interval counter. A low-to-high transition on OUT0 (counter 0

output) initiates a conversion. You can program counter 0 to

generate a pulse once every N µs. N is referred to as the sample

interval; that is, the time between successive A/D conversions.

N can be between 20 and 65,535. The sample interval is equal to the

period of the timebase clock used by counter 0 multiplied by N.

A 1 MHz clock is internally connected to CLK0 (the clock used by

counter 0).

Use the following programming sequence to program counter 0, the

sample-interval counter. All writes are 8-bit write operations. All

values given are hexadecimal.

a. Write 34 to the Counter Mode Register (select counter 0,

mode 2).

b. Write the least significant byte of the sample interval to the

Counter 0 Data Register.

c. In Step a., writing to the Counter Mode Register forces OUT0

to high. To finish programming counter 0, you must also write

the most significant byte. However, this writing starts the

counting, so perform this writing in step 4.

3. Clear the A/D circuitry.

Before starting the data acquisition operation, empty the A/D FIFO

to clear out any old A/D conversion results. You must do this after

programming the counters in case any spurious edges were caused

a.Book : l.Appendix D Page 31 Wednesday, November 20, 1996 6:36 PM

Contents

Main Page Important Information WARNING REGARDING MEDICAL AND CLINICAL USE OF NATIONAL INSTRUMENTS PRODUCTS Trademarks Copyright Page Page Glossary Index Figures Tables About This Manual Organization of This Manual Conventions Used in This Manual National Instruments Documentation Related Documentation Customer Communication Introduction About the PC-LPM-16/PnP What You Need to Get Started LabVIEW and LabWindows/CVI Application Software Software Programming Choices NI-DAQ Driver Software Register-Level Programming Optional Equipment Custom Cables Unpacking Installation and Configuration Hardware Installation Software Installation Plug and Play Board Configuration Base I/O Address and Interrupt Selection Non-Plug and Play Theory of Operation Functional Overview Chapter 3 Theory of Operation Figure 3-1. PC-LPM-16PnP Block Diagram PC I/O Channel Interface Circuitry Analog Input and Data Acquisition Circuitry Analog Input Circuitry Data Acquisition Timing Circuitry Single-Channel Data Acquisition Data Acquisition Rates Multichannel Scanning Data Acquisition Chapter 3 Theory of Operation PC-LPM-16/PnP User Manual 3-8 Digital I/O Circuitry Digital I/O Circuitry Block Diagram Figure 3-4. Timing I/O Circuitry Page Signal Connections I/O Connector Chapter 4 Signal Connections Figure 4-1. PC-LPM-16PnP I/O Connector Pin Assignments Signal Connection Descriptions Page Analog Input Signal Connections Connections for Signal Sources Digital I/O Signal Connections Power Connections Power Rating Data Acquisition Timing Connections Timing Connections General-Purpose Timing Signal Connections and General-Purpose Counter Timing Signals Page Page Page Specifications A Transfer Characteristics PC-LPM-16PnP Board Amplifier Characteristics Digital I/O Stability Dynamic Characteristics Timing I/O Bus Interface Explanation of Analog Input Specifications Environment Physical Page Page B MSM82C53 Data Sheet Page Page Page Page Page Page Page Page Page Page Page Using Your PC-LPM-16 (Non-PnP) Board C the PC-LPM-16 Differences between the PC-LPM-16PnP and Page Page Configuration and Installation of the Board Configuration PC-LPM-16 (non-PnP) Page Base I/O Address Selection Page Page Interrupt Selection Analog Input Jumper Settings 5 V) Bipolar Input Selection 1 ( Bipolar Input Selection 2 ( Unipolar Input Selection 1 (0 to 10 V) Select the bipolar ( 2.5 V) 2.5 V) input configuration by setting jumpers W1 and W2 as shown in Figure C-6. Unipolar Input Selection 2 (0 to 5 V) Installation Register-Level Programming D Register Map Base Address Register Size Register Descriptions Register Description Format Configuration and Status Register Group Page Page Page Command Register 2 Command Register 2 Command Register 3 Status Register 1 Status Register 1 Page Status Register 2 Analog Input Register Group A/D FIFO Low-Byte Register and A/D FIFO High-Byte Register A/D FIFO Low-Byte Register and A/D FIFO High-Byte Register A/D Clear Register Counter/Timer (MSM82C53) Register Group Counter 0 Data Register Counter 1 Data Register Counter 2 Data Register Page Page Page Timer Interrupt Clear Register Digital I/O Register Group Digital Output Register Digital Input Register Programming Considerations Register Programming Considerations Initializing the PC-LPM-16/PnP Programming the A/D Calibration Programming the Analog Input Circuitry Analog Input Circuitry Programming Sequence A/D FIFO Output Binary Modes Clearing the Analog Input Circuitry Programming Multiple A/D Conversions on a Single Input Channel Using Counter 0 Page Page Programming Multiple A/D Conversions Using External Timing Programming Multiple A/D Conversions with Channel Scanning A/D Interrupt Programming Programming the Digital I/O Circuitry Programming the MSM82C53 Counter/Timer Customer Communication FTP Support Electronic Services E Bulletin Board Support Telephone and Fax Support Telephone Fax Fax-on-Demand Support E-Mail Support (currently U.S. only) Technical Support Form PC-LPM-16/PnP Hardware and Software Configuration Form Other Products National Instruments Products Documentation Comment Form Glossary Symbols A C B Page Page T V A Numbers Index B C D E I H F G J P N M O R S T U