Motorola MPC533 Reference Manual page 361

MPC5xx Device
External Bus
Interface
lwarx
S Q
R
CLKOUT
The MPC533 samples the CR line at the rising edge of CLKOUT. When this signal is
asserted, the reservation flag is reset (negated).
The external bus interface (EBI) samples the logical value of the reservation flag prior to
externally starting a bus cycle initiated by the RCPU stwcx instruction. If the reservation
flag is set, the EBI begins with the bus cycle. If the reservation flag is reset, no bus cycle is
initiated externally, and this situation is reported to the RCPU.
The reservation protocol for a multi-level (local) bus is illustrated in Figure 9-31. The
system describes the situation in which the reserved location is sited in the remote bus.
MOTOROLA
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
AT[0:3], RSV, R/W, TS
CR
Figure 9-30. Reservation On Local Bus
Chapter 9. External Bus Interface
External Bus
ADDR[0:29]
Reservation
Logic
Bus Operations
Bus
Master
CR
9-45