MPC555
/
MPC556
EXTERNAL BUS INTERFACE
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
9-34
illustrates the internal finite-state machine that implements the arbiter pro-
tocol.
Table 9-4 Priority Between Internal and External Masters over External Bus
1
NOTES:
1. External master will be granted external bus ownership if EARP is greater than the internal access pri-
ority.
Type
Direction
Priority
Parked access
2
2. Parked access is instruction or data access from the RCPU which is initiated on the internal bus without
requesting it first in order to improve performance.
Internal
→
external
0
Instruction access
Internal
→
external
3
Data access
Internal
→
external
4
External access
external
→
external/internal
EARP
3
(could be programmed to 0 – 7)
6.13.1.1 SIU Module Configuration Register
.
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Freescale Semiconductor, Inc.
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