User manual

Appendix F DMA Programming Examples

/* The following write is required to initialize the DMAICR. In

this example, the DMA interrupt is being routed to VMEbus IRQ5*.

You can route the DMA interrupt to any VMEbus interrupt level in

the DMAICR. You can put the DMA interrupt on the same level as

other interrupt conditions on the VXI-MXI-2 as well as interrupt

conditions on other devices. This write is also programming the

DMA interrupt condition to use a 16-bit Status ID when being

acknowledged. You can change this write if you prefer an 8-bit

Status ID. If you select an 8-bit Status ID you should also decide

if you want the contents of the DMAISIDR or the VXI-MXI-2 module's

logical address returned during the interrupt acknowledge cycle.

write(A24, A24BASE + DMAICR, WORD, 0x2805);

/* The following write is required to initialize the DMAIER. This

is simply enabling the DMA interrupt condition to be routed to the

VMEbus. */

write(A24, A24BASE + DMAIER, BYTE, 0x09);

/* The following write sets up the DMAISIDR. This is just a Status

ID code that the VXI-MXI-2 will return during an interrupt

acknowledge cycle for the DMA interrupt condition. You should

program a code that you can use in your interrupt service routine

to uniquely identify the VXI-MXI-2 module's DMA interrupt

condition. Remember that you can change only the 5 most

significant bits of the Status ID using the DMAISIDR. For a 16-bit

Status ID, the VXI-MXI-2 always uses 011 binary for bits 10

through 8 and its logical address for bits 7 through 0. For an

8-bit Status ID, the VXI-MXI-2 can return either the contents of

the DMAISIDR (the value you write here with bits 2 through 0

forced to 011 binary) or the logical address of the VXI-MXI-2

module. */

write(A24, A24BASE + DMAISIDR, WORD, 0x0013);