MPC563XM Reference Manual, Rev. 1
Freescale Semiconductor
311
Preliminary—Subject to Change Without Notice
In 16-bit Data Bus Mode, (or for chip-select accesses to a 16-bit port), only DATA[0:15] or DATA[16:31]
are used by the EBI, depending on the setting of the D16_31 bit in the EBI_MCR. See
.
13.3.2.10 OE — Output Enable
OE is used to indicate when an external memory is permitted to drive back read data. External memories
must have their data output buffers off when OE is negated. OE is only asserted for chip-select accesses.
OE is driven by the EBI or an external master depending on who owns the external bus. For read cycles,
OE is asserted one clock after TS assertion and held until the termination of the transfer. For write cycles,
OE is negated throughout the cycle.
13.3.2.11 RD_WR — Read / Write
RD_WR indicates whether the current transaction is a read access or a write access.
RD_WR is driven by the EBI or an external master depending on who owns the external bus. RD_WR is
driven in the same clock as the assertion of TS and valid address, and is kept valid until the cycle is
terminated.
13.3.2.12 TA — Transfer Acknowledge
TA is asserted to indicate that the slave has received the data (and completed the access) for a write cycle,
or returned data for a read cycle. If the transaction is a burst read, TA is asserted for each one of the
transaction beats. For write transactions, TA is only asserted once at access completion, even if more than
one write data beat is transferred.
TA is driven by the EBI when the access is controlled by the chip selects (and SETA=0) or when an
external master initiated the transaction to an internal module. Otherwise, TA is driven by the slave device
to which the current transaction was addressed.
Section 13.5.2.9, “Termination Signals Protocol
for more details.
13.3.2.13 TEA — Transfer Error Acknowledge
TEA is asserted by either the EBI or an external device to indicate that an error condition has occurred
during the bus cycle.
TEA is asserted by the EBI when the internal bus monitor detected a timeout error, or when an external
master initiated a transaction to an internal module and an internal error was detected.
Section 13.5.2.9, “Termination Signals Protocol
for more details.
13.3.2.14 TS — Transfer Start
TS is asserted by the current bus owner to indicate the start of a transaction on the external bus.
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