Freescale Semiconductor MPC5565, Reference Manual

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External Bus Interface (EBI)
MPC5565 Microcontroller Reference Manual, Rev. 1.0
12-10 Freescale Semiconductor
TA is driven by the EBI when the access is controlled by the chip selects or when an external master
initiates the transaction to an internal module. Otherwise, TA is driven by the slave device to which the
current transaction was addressed.
During a calibration bus access, TA is held negated.
Refer to Section 12.4.2.9, “Termination Signals Protocol ” for more details.
12.2.1.9 Transfer Error Acknowledge (TEA)
The 324 BGA package does not support the TEA signal.
The VertiCal assembly supports the TEA signal.
During a calibration bus access, TEA is held negated.
Refer to Section 12.4.2.9, “Termination Signals Protocol ” for more details.
12.2.1.10 Transfer Start (TS)
TS is asserted by the current bus owner to indicate the start of a transaction on the external bus.
TS is driven by the EBI or an external master depending on who owns the external bus. TS is only asserted
for the first clock cycle of the transaction, and is negated in the successive clock cycles until the end of the
transaction.
During a calibration bus access, TS is held negated.
12.2.1.11 Write/Byte Enables (WE/BE)
Write enables are used to enable program operations to a particular memory. These signals can also be used
as byte enables for read and write operation by setting the WEBS bit in the appropriate base register.
WE/BE are only asserted for chip select accesses.
WE/BE signals are driven by the EBI or an external master depending on the module that controls the
external bus.
The VertiCal assembly uses WE/BE[0:3].
The 324 BGA package uses WE/BE[0:1].
During a calibration bus access, WE/BE signals are held negated.
Refer to Section 12.4.1.14, “Two Write/Byte Enable (WE/BE) Signals — 324 BGA Package ” and
Section 12.4.1.13, “Four Write/Byte Enable (WE/BE) Signals — VertiCal Assembly ” for more details on
the WE/BE functionality.
12.2.1.12 Bus Busy (BB), Bus Grant (BG) and Bus Request (BR)
The MPC5565 does not implement the BB, BG, or BR signals.