
MOTOROLA
Chapter 8. Signal Descriptions
8-27
Signal Descriptions
tenure has already started, the core also aborts the data tenure
immediately, even if the burst data has been received. If the core is
not the address bus master, this input indicates that the core should
immediately negate core_br for one bus clock cycle following the
assertion of core_artry_in by the snooping bus master to allow an
opportunity for a copy-back operation to main memory. Note that the
subsequent address presented on the address bus may not be the same
one associated with the assertion of core_artry_in.
Negated—Indicates that the core does not need to retry the last
address tenure.
Assertion—May occur as early as the second cycle following the
assertion of core_ts_out, and must occur by the bus clock cycle
immediately following the assertion of core_aack if an address retry
is required.
Negation—Must occur during the second cycle after the assertion of
core_aack.
Timing Comments
8.3.5.2.2
Address Retry Out (core_artry_out)
The core also implements address retry output enable and address retry high-impedance
enable signals. core_artry_out acts as follows:
If core_artry_tre is asserted, the output is in one of the following three states—high
impedance, driven high, or driven low.
If core_artry_tre is negated, the output is either driven to the high or low state. In this
case, a valid value on core_artry_out exists when core_artry_oe is asserted.
Following are the state meaning and timing comments for core_artry_out.
State Meaning
Asserted—Indicates that the G2 core detects a condition in which a
snooped address tenure must be retried. If the core needs to update
memory as a result of the snoop that caused the retry, the core asserts
core_br the second cycle after core_aack if core_artry_out is
asserted.
Negated—Indicates that the core does not need the snooped address
tenure to be retried.
Timing Comments
Assertion—Asserted the third bus cycle following the assertion of
core_ts_in if a retry is required and remains asserted until one cycle
after the core_aack is asserted.
Negation—Occurs on the second bus cycle after the assertion of
core_aack and remains asserted for a minimum of one-half bus cycle
(depends on clock mode) before it is negated for one bus cycle.
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