12. Register Descriptions
284
PowerSpan II User Manual
80A1010_MA001_09
Integrated Device Technology
www.idt.com
12.5.22
PCI-1 Bus Arbiter Control Register
PowerSpan II’s PCI-1 interface has dedicated support for four external PCI masters. The user can
assign up to three additional PCI masters to the PCI-1 arbiter by configuring the PCI_M7 bit, the
PCI_M6 bit, and the PCI_M5 in the
“Miscellaneous Control and Status Register” on page 318
.
The PowerSpan II PCI-1 internal arbiter is enabled by a power-up option. When disabled, an external
arbiter is used. The signals P1_REQ[1]_/P1_GNT[1]_ are used by the PowerSpan II PCI-1 Master to
arbitrate for access to the bus.
The P1_ARB_EN bit in the
“Reset Control and Status Register” on page 324
arbiter is enabled or disabled.
Depending on the number of external masters supported, some of bits M4-M7
and combinations of BM_PARK are not applicable. Programming these
combinations result in unpredictable PowerSpan II behavior.
Register Name: P1_ARB_CTRL
Register Offset: 0x164
PCI
Bits
Function
PB
Bits
31-24
PowerSpan II Reserved
0-7
23-16
STATUS_BITS
8-15
15-08
M7_PRI
M6_PRI
M5_PRI
M4_PRI
M3_PRI
M2_PRI
M1_PRI
PS_PRI
16-23
07-00
PowerSpan II Reserved
STATUS_
EN
PARK
BM_PARK
24-31
Name
Type
Reset
By
Reset
State
Function
STATUS_
BITS
R/W
P1_RST
0
Operational status of PCI Master Device
x
These series of bits are separated per master. There is one
bit designated for each master and is separate from the
others, but all eight are called STATUS_BITS[7:0]. The
individual bits are set when a PCI Master does not respond to
a grant given by the PowerSpan II arbiter for 16 clock cycles.
Once this bit is set to 1 by the PowerSpan II arbiter, the
PowerSpan II arbiter does not include the non-functioning
PCI Master in the arbitration algorithm used by PowerSpan II.
When the bit is set to 0, the operating status of the PCI
Master is functioning and it is included in the arbitration
algorithm used by PowerSpan II.
0 = functioning
1 = non-functioning