
MOTOROLA
Chapter 9. External Bus Interface
9-5
Bus Interface Signal Descriptions
RSV
Reservation transfer
1
Low
O
Driven by the MPC565/MPC566 along with the
address when it owns the external bus. Indicates
additional information about the address on the
current transaction.
I
Only for testing purposes.
PTR
Program trace
1
High
O
Driven by the MPC565/MPC566 along with the
address when it owns the external bus. Indicates
additional information about the address on the
current transaction.
I
Only for testing purposes.
BDIP
Burst data in progress
1
Low
O
Driven by the MPC565/MPC566 when it owns the
external bus. It is part of the burst protocol. When
BDIP is asserted, the second beat in front of the
current one is requested by the master. This signal is
negated prior to the end of a burst to terminate the
burst data phase early.
I
Driven by an external master when it owns the external
bus. When BDIP is asserted, the second beat in front
of the current one is requested by the master. This
signal is negated prior to the end of a burst to
terminate the burst data phase early. The
MPC565/MPC566 does not support burst accesses to
internal slaves.
Transfer Start
TS
Transfer start
1
Low
O
Driven by the MPC565/MPC566 when it owns the
external bus. Indicates the start of a transaction on the
external bus.
I
Driven by an external master when it owns the external
bus. It indicates the start of a transaction on the
external bus or (in show cycle mode) signals the
beginning of an internal transaction.
STS
Special transfer start
1
Low
O
Driven by the MPC565/MPC566 when it owns the
external bus. Indicates the start of a transaction on the
external bus or signals the beginning of an internal
transaction in show cycle mode.
Reservation Protocol
CR
Cancel reservation
1
Low
I
Each MPC500 CPU has its own CR signal. Assertion
of CR instructs the bus master to clear its reservation;
some other master has touched its reserved space.
This is a pulsed signal.
KR
Kill reservation
1
Low
I
Incaseofabuscycle initiatedbyaSTWCX instruction
issued by the RCPU to a non-local bus on which the
storage reservation has been lost, this signal is used
by the non-local bus interface to back-off the cycle.
details.
Table 9-1. MPC565/MPC566 SIU Signals (continued)
Signal Name
Pins
Active
I/O
Description