Chapter 4
Register Descriptions
© National Instruments Corporation
4-61
GPIB-1014 User Manual
Channel Priority Register
VMEbus Address:
Base A 2D (hex)
Attributes:
Read/Write, Internal to DMAC
7
6
5
4
3
2
0
CP
0
0
0
0
0
0
R/W
The Channel Priority Register (CPR) is used to define the priority level for each channel. The
priority of a channel is a number from 0 through 3, with 3 being the highest priority level. When
multiple requests for DMA service are pending at the DMAC, the channel with the highest
priority receives first service. Channel priority is also used to determine which channel is
serviced first when multiple channels have interrupts pending. If there are several requesting
channels at the highest priority level, a round-robin resolution is used. For the GPIB-1014
application, channel 0 and channel 1 priority are the same.
Bit
Mnemonic
Description
7-2r/w
0
Reserved Bits
Write zeros to these bits.
1-0r/w
CP
Channel Priority Bits 1 through 0
The Channel Priority bits indicate the channel priority.
00 =
Priority level 0
01 =
Priority level 1
10 =
Priority level 2
11 =
Priority level 3