TC1796
System Units (Vol. 1 of 2)
LMB External Bus Unit
User’s Manual 13-13 V2.0, 2007-07
EBU, V2.0
Figure 13-5 Bus Ownership Control in Arbiter Mode
MCA05716
EBU in Owner Mode
(i.e. owner of the
external bus)
The EBU holds ownership of the
external bus:
While EXTLOCK = 1
or
Until all current/queued external
accesses are completed.
When the external master requests
the external bus (HOLD = 0) and
conditions are appropriate the EBU
releases ownership of the bus by
HLDA = 0.
Start
PLMB access
to external bus
is starting?
EBU_CON.
EXTLOCK = 1?
HOLD = 0?
EBU in Hold Mode
(i.e. not owner of the
external bus)
Perform Appropriate
External Bus Access
(for read access return
result to PLMB)
yes
no
yes
no
no
yes
HOLD = 0?
yes
no
The EBU remains in Hold Mode
until the bus is released by the
external master (signalled by the
external master setting HOLD = 1).
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