Functional Description - STMicroelectronics SPC572L series Reference Manual

Crossbar Switch (XBAR)
Field
High Priority Enable
Determines if Master x is able to temporarily elevate it's request to the slave to high priority
status. This can help reduce the amount of time the high priority requesting master must wait to
8–15
gain control of the slave.
HPEx
0 High Priority requests from Master x are ignored and are treated the same as regular requests.
1 High Priority requests from Master x can temporarily elevate the priority level of the master's
request to the slave.
16–21
This read-only bitfield is reserved and always has the value zero.
Reserved
Arbitration mode
Selects the arbitration policy for the slave port.
22–23
00 Fixed priority
ARB
01 Round-robin (rotating) priority
10 Reserved
11 Reserved
24–25
This read-only bitfield is reserved and always has the value zero.
Reserved
Parking control
Determines the slave port's parking control. The low-power park feature results in overall power
savings if the slave port is not saturated; however, this forces an extra latency clock when any
master tries to access the slave port while not in use because it is not parked on any master.
00 When no master makes a request, the arbiter parks the slave port on the master port defined
26–27
by the PARK bit field.
PCTL
01 When no master makes a request, the arbiter parks the slave port on the last master to be in
control of the slave port.
10 When no master makes a request, the slave port is not parked on a master and the arbiter
drives all outputs to a constant safe state.
11 Reserved
28
This read-only bit is reserved and always has the value zero.
Reserved
Park
Determines which master port the current slave port parks on when no masters are actively
making requests and the PCTL bits are cleared.
Note: Only select master ports that are actually present on the device. If not, undefined behavior
000 Park on master port M0
29–31
001 Park on master port M1
PARK
010 Park on master port M2
011 Park on master port M3
100 Park on master port M4
101 Park on master port M5
110 Park on master port M6
111 Park on master port M7
14.2

Functional description

This section provides the functional details of the crossbar switch.
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Table 134. XBAR_CRSn field descriptions(Continued)
may occur.
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Description
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