mcf5407 Freescale Semiconductor, Inc, mcf5407 Datasheet - Page 229

• Manufacturer Part Number: mcf5407
• Description: Mcf5407 Coldfire Integrated Microprocessor User
• Manufacturer: Freescale Semiconductor, Inc

• In multiple-master systems, disabling arbitration with EARBCTRL allows
memories from responding to internal register transfers that go to the external bus.
The AS signal and all chip-select-related strobe signals are not asserted.
Do not immediately follow a cycle in which SHOWDATA is set with a cycle using
fast termination.
performance improvement because internal register bus transfer cycles do not
interfere with the external bus.
Having internal transfers go external may affect performance in two ways:
— If the internal device does not control the bus immediately, the core stalls until it
— If the core wins arbitration instantly, it may kick the external master off of the
wins arbitration of the external bus.
external bus unnecessarily for a transfer that did not need the external bus. For
debug, where this performance penalty is not a concern, setting EARBCTRL and
SHOWDATA provides external visibility of the internal bus cycles.
Chapter 6. SIM Overview
Programming Model
6-15