National Instruments 320030-01 Using Programmed I/O

Programming Considerations Chapter 5

GPIB-1014 User Manual 5-20 © National Instruments Corporation

Whether terminating on the END message or the EOS message (or whenever the DMA transfer

does not complete properly), the DMAC must be stopped by issuing a software abort to Channels

0 and 1 by writing to the CCR with the SAB bit set. You then must write to the CSR to clear the

ERR flag set by the software abort.

Using Programmed I/O

Programming considerations for using programmed I/O data transfers are explained in the

following paragraphs.

Sending and Receiving Data

When using programmed I/O to send or receive a GPIB data byte, the DMAO and DMAI bits in

IMR2 must be cleared. The contents of other GPIB-1014 DMA registers are irrelevant.

To send data, wait until the TLC has been programmed or addressed to talk and the CDOR is

empty. When this occurs, the DO bit in the ISR1 is set, indicating that it is safe to write a byte to

the CDOR. The DO bit is set again once that byte has been received by all Listeners.

To receive data, wait until the TLC has been programmed or addressed to listen and the DIR is

full. When this occurs, the DI bit in ISR1 is set, indicating that the GPIB Talker has written a

byte to the DIR. Once that byte has been read, the DI bit is set again when a new byte is received

from the Talker.

To determine if the CDOR is empty or if the DIR is full, either poll ISR1 until the DO or DI

status first appears, or allow a program interrupt to occur on the respective event. Remember,

however, that the status bits and the interrupt signals are cleared when the ISR1 is read, so the

absence of a true DO or DI status does not unambiguously indicate that the CDOR is still full or

that the DIR is still empty.

Sending END or EOS

Send the GPIB END message by issuing the Send EOI auxiliary command just before writing the

last data byte to the CDOR. To send the GPIB EOS message, make the last byte the EOS code.

Terminating on END or EOS

The END status bit or interrupt is used to inform the program of the occurrence of an END

message or an EOS message.

Contents

Main Page Limited Warranty Copyright Trademarks Page FCC/DOC Radio Frequency Interference Compliance Federal Communications Commission Canadian Department of Communications Instructions to Users Contents Chapter 5 Programming Considerations Chapter 6 Theory of Operation Page Appendix F Mnemonics Key Appendix G Customer Communication Glossary Index Figures Tables About This Manual Organization of This Manual Conventions Used in This Manual Related Documentation Customer Communication Chapter 1 Introduction Page What Your Kit Should Contain Optional Equipment Unpacking Chapter 2 General Description Electrical Characteristics VMEbus Characteristics VMEbus Slave-Addressing VMEbus Slave-Data Table 2-3. 68450 Internal DMA Registers Ad (continues) VMEbus Master-Direct Memory Access Interrupter Data Transfer Bus (DTB) Requester Diagnostic Aids Data Transfer Features Programmed I/O Transfers GPIB-1014 Functional Description Chapter 2 General Description Figure 2-1. GPIB-1014 with a VMEbus Computer National Instruments Corporation 2-9 GPIB-1014 User Manual General Description Chapter 2 Figure 2-2. GPIB-1014 in a Multiprocessor Application GPIB-1014 User Manual 2-10 National Instruments Corporation Chapter 2 General Description National Instruments Corporation 2-11 GPIB-1014 User Manual Figure 2-3 is a block diagram of the GPIB-1014. Figure 2-3. GPIB-1014 Block Diagram Page Page Page Page Page Page Access Mode Base Address Page DMA Address Modifier Code Output Page Other Configuration Parameters Installation Verification of System Compatibility Configuration and Installation Chapter 3 GPIB-1014 User Manual 3-8 National Instruments Corporation Table 3-3. GPIB-1014 Pin Assignment on VMEbus Connector P1 Pin No. Signal Used Signal Not Used Pin No. Signal Used Signal Not Used Chapter 3 Configuration and Installation National Instruments Corporation 3-9 GPIB-1014 User Manual Table 3-4. GPIB-1014 Pin Assignment on VMEbus Connector P2 Signal Signal Signal Signal Pin No. Used Not Used Notes Pin No. Used Not Used Notes Notes Cabling Verification Testing Chapter 4 Register Bit Descriptions Register Map Register Sizes Register Description Page Interface Registers Figure 4-1. Interface Registers Figure 4-2. Writing to the Hidden Registers Data In Register (DIR) Command/Data Out Register (CDOR) Interrupt Status Register 1 (ISR1) Interrupt Mask Register 1 (IMR1) Page Page Page Page Page Interrupt Status Register 2 (ISR2) Interrupt Mask Register 2 (IMR2) Page Page Page Page Serial Poll Status Register (SPSR) Serial Poll Mode Register (SPMR) Address Status Register (ADSR) Page Address Mode Register (ADMR) Page Page Command Pass Through Register (CPTR) Page Auxiliary Mode Register (AUXMR) Page Page Page Page Page Hidden Registers Page Page Page Page Page Page Page Page Address Register 0 (ADR0) Address Register (ADR) Address Register 1 (ADR1) End of String Register (EOSR) DMA Registers Chapter 4 Register Descriptions Figure 4-3. DMA Register Memory Map National Instruments Corporation 4-47 GPIB-1014 User Manual Reprinted from the Motorola MC68440 Advance Information manual. Address Registers Transfer Count Registers Function Code Registers Device Control Register Page Operation Control Register Page Sequence Control Register Channel Control Register Page Channel Status Register Page Channel Error Register Channel Priority Register Interrupt Vector Registers General Control Register Configuration Registers Page Page Page Chapter 5 Programming Considerations Initialization Page The GPIB-1014 as GPIB Controller Becoming Controller-In-Charge (CIC) and Active Controller Sending Remote Multiline Messages (Commands) Going from Active to Standby Controller Going from Standby to Active Controller Going from Active to Idle Controller The GPIB-1014 as GPIB Talker and Listener Programmed Implementation of Talker and Listener Addressed Implementation of the Talker and Listener Page Sending/Receiving Messages Using Direct Memory Access Page Page Page Page Page Page Page Page Page Page Page Using Programmed I/O Interrupts Page Serial Polls Conducting a Serial Poll Responding to a Serial Poll Parallel Polls Conducting a Parallel Poll Responding to a Parallel Poll Chapter 6 Theory of Operation VMEbus Interface Data Lines Control Signals Address Control Equations of Transceivers Address Decoding Clock and Reset Circuitry Configuration Registers Configuration Register 1 Page Configuration Register 2 Timing State Machine Slave Cycles DMA Cycles DMA Gating and Control Interrupter DTB Requester and Controller Page Page GPIB Synchronization and Interrupt Control Page Page 68450 DMAC DMAC Channel Operation Page Page Page Page Page Page Page Page Page GPIB Interface Test and Troubleshooting DMA Stand-Alone Testing GPIB Interface Testing Page Chapter 7 Diagnostic and Troubleshooting Test Procedures Interpreting Test Procedures GPIB-1014 Hardware Installation Tests Page Page Page Page Page Page Page Appendix A Hardware Specifications Page Page Appendix C Sample Programs ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Multiline Interface Messages Hex Oct Dec ASCII Msg Hex Oct Dec ASCII Msg Message Definitions Multiline Interface Messages Hex Oct Dec ASCII Msg Hex Oct Dec ASCII Msg Appendix E Operation of the GPIB Types of Messages Talkers, Listeners, and Controllers The Controller-In-Charge and System Controller GPIB Signals and Lines Data Lines Handshake Lines Interface Management Lines Operation of the GPIB Appendix E GPIB-1014 User Manual E-4 National Instruments Corporation Physical and Electrical Characteristics Figure E-1. The GPIB Connector and Signal Assignments Page Configuration Requirements Related Documents Appendix F Mnemonics Key A B Page C D E F G H I L M N O P R S T Page Appendix G Customer Communication Technical Support Form ____________________________________________________ GPIB-1014 Hardware and Software Configuration Form National Instruments Products Other Products Page Documentation Comment Form Glossary ___________________________________________________ Index Numbers A B C D Page Page Page E F G H I Page J L M N O P Page R S Page T Page Page U V W