MPC563XM Reference Manual, Rev. 1
408
Freescale Semiconductor
Preliminary—Subject to Change Without Notice
13.6.8
Summary of Differences from MPC5xx
Below is a summary list of the significant differences between this EBI and that of the MPC5xx parts.
•
No memory controller support for external masters
— must configure each master in multi-master system to drive its own chip selects
— rationale: save complexity, no requirement for this feature
•
Burst mechanism updated to be compatible with e200z core with 32-byte cache line
— rationale: required for performance and compatibility with e200z core
•
Removed these variable timing attributes from Option Register:
— CSNT, ACS, TRLX, EHTR
— rationale: reduces tester edgesets and complexity, no clear requirements for these features
•
Removed reservation support on external bus
— rationale: reservation not supported on internal bus, useless to support on external
•
Removed Address Type (AT), Write-Protect (WP), and dual-mapping features
— rationale: these functions can be replicated by Memory Management Unit (MMU) in e200z
core
•
Removed support for 8-bit ports
— rationale: reduces complexity and not required
•
Removed boot chip-select operation
— rationale: on-chip Boot Assist Module (BAM) handles boot (and configuration of EBI
registers)
•
Open drain mode and pullup resistors no longer required for multi-master systems, extra cycle
needed to switch between masters
— rationale: saves customer hassle for multi-master system setup, at negligible performance cost
•
Address decoding for external master accesses uses 4-bit code to determine internal slave instead
of straight address decode
— rationale: needed for compatibility with internal bridge address decoding and memory map
•
Removed support for 3-master systems
— rationale: very difficult to manage with internal bridge address decoding method and keep
memory maps unique; not an essential feature to justify complexity of supporting
•
Removed LBDIP Base Register bit, now late BDIP assertion is default behavior
— rationale: unaware of any memories that require BDIP to assert earlier than LBDIP timing, so
reduce number of CS control bits and complexity
•
Modified arbitration protocol to require extra cycles when switching between masters
— rationale: could not use exact Oak protocol and make timing for full-speed operation; adding
dead cycles to protocol allows bus to run full-speed in external master mode and makes this
feature not limit overall EBI frequency
•
Modified TSIZ[0:1] functionality to only indicate size of current transfer, not give information on
ensuing transfers that may be part of the same atomic sequence