12. Register Descriptions
315
PowerSpan II User Manual
80A1010_MA001_09
Integrated Device Technology
www.idt.com
DBS[1:0]
R/W
G_RST
0
DMA Block Size (when DBS_EN is set to 1)
Controls the byte size of transactions generated by the DMA
channel. The DBS_EN bit must be set to 1 in order for the
DBS functionality to be enabled.
00=32 bytes
01=16 bytes
10=8 bytes
11=4 bytes
DBS_EN
R/W
G_RST
0
DMA Block Size Enable
Provides programmable control over the byte size of
transactions generated by the DMA channel. The byte size is
based on values programmed into DBS[1:0].
0 = not active
1 = active
OFF
R/W
G_RST
0
DMA Channel Off Counter (number of PB clocks)
Provides programmable control over the amount of source
bus traffic generated by the DMA channel. The channel will
interleave source bus transfers with a period of idle
Processor Bus clocks where no source bus requests are
generated. When source and destination ports are different,
256 bytes of source bus traffic occur before the idle period. If
source and destination ports are the same, 64 bytes of
source bus traffic occur before the idle period. This helps
prevent PowerSpan II from interfering with Processor Bus
instruction fetches.
000 = 0
001 = 128
010 = 256
011 = 512
100 = 1024
101 = 2048
110 = 4096
111 = 8192
P1_ERR
R/Write 1 to
Clear
G_RST
0
PCI-1 Bus Error
0 = no error
1 = error
P2_ERR
R/Write 1 to
Clear
G_RST
0
PCI-2 Bus Error
0 = no error
1 = error
Single PCI PowerSpan II: Reserved
Name
Type
Reset
By
Reset
State
Function