User manual

Appendix F DMA Programming Examples

VXI-MXI-2 User Manual F-2 © National Instruments Corporation

Parameter Descriptions

The parameters for both functions are ADDRESS_SPACE, ADDRESS,

TRANSFER_SIZE, and DATA.

• ADDRESS_SPACE represents the VMEbus address space in which

the write or read will take place. The examples assume the

VXI-MXI-2 is located in A24 space.

• ADDRESS represents the address in the memory space to which to

perform the write or read. In the examples, A24BASE represents

the base A24 address of the VXI-MXI-2. Any register name in the

examples represents the offset of that register defined in Chapter 5,

• The TRANSFER_SIZE parameter can be one of BYTE, WORD, or

LONGWORD representing 8-bit, 16-bit, and 32-bit data transfers,

respectively.

• The DATA parameter is a constant for writes that represents the

data to be written and is a program variable for reads that store the

data read.

Example 1: DMA Operation without Interrupt

This example simply programs DMA controller 1 to move data from

the source on the VMEbus to the destination on the MXIbus. The

source is located in A24 space beginning at address location 200000

hex. VMEbus 32-bit block cycles are used to read data from the source.

The destination is located in A32 space beginning at address location

40000000 hex. MXIbus 32-bit synchronous burst cycles are used to

write data to the destination.

/************************************************************

* *

* Initialization: This section needs to be executed only *

* once prior to any DMA activity and does not have to be *

* repeated for each DMA operation. *

* *

************************************************************/