MPC555
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MPC556
EXTERNAL BUS INTERFACE
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
9-54
Figure 9-39 Retry of External Master Access (Internal Arbiter)
9.5.13 Show Cycle Transactions
Show cycles are accesses to the CPU’s internal bus devices. These accesses are
driven externally for emulation, visibility, and debugging purposes. A show cycle can
have one address phase and one data phase, or just an address phase in the case of
instruction show cycles. The cycle can be a write or a read access. The data for both
the read and write accesses should be driven by the bus master. (This is different from
normal bus read and write accesses.) The address and data of the show cycle must
each be valid on the bus for one clock. The data phase must not require a transfer ac-
CLKOUT
ADDR[0:31]
TS
BR
BG (output)
BB
Data
TA
RD/WR
BURST
TSIZ[0:1]
RETRY(output)
ADDR (ext)ernal
ADDR (internal)
Allow Internal
Access to Gain the
Note: the delay for the internal to external cycle may be one clock or greater.
Bus
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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