Motorola MPC823e User Manual

External Bus Interface
13-4 MPC823e REFERENCE MANUAL MOTOROLA
EXTERNAL BUS
13
INTERFACE
13.3 BUS SIGNAL DESCRIPTIONS
The following table decribes each bus interface signal. More detailed descriptions can be
found in subsequent sections of this manual.
Table 13-1. Bus Interface Signals
MNEMONIC PINS ACTIVE I/O DESCRIPTION
ADDRESS AND TRANSFER ATTRIBUTES
A[6:31] 26 High O Address Bus —Driven by the MPC823e when it owns
the external bus. It specifies the physical address of
the bus transaction. These signals can change during
a transaction when controlled by the memory
controller.
I Sampled by the MPC823e when an external device
initiates a transaction and the memory controller was
configured to handle external master accesses.
RD/WR
1 High O Read/Write —Driven by the MPC823e along with the
address when it owns the external bus. Driven high
indicates that a read access is in progress and driven
low indicates that a write access is in progress.
I Sampled by the MPC823e when an external device
initiates a transaction and the memory controller was
configured to handle external master accesses.
BURST
1 Low O Burst Transfer —Driven by the MPC823e along with
the address when it “owns” the external bus. Driven
low indicates that a burst transfer is in progress and
driven high indicates that the current transfer is not a
burst.
I Sampled by the MPC823e when an external device
initiates a transaction and the memory controller was
configured to handle external master accesses.
TSIZ[0:1] 2 High O Transfer Size —Driven by the MPC823e along with
the address when it owns the external bus. It specifies
the data transfer size for the transaction.
I Sampled by the MPC823e when an external device
initiates a transaction and the memory controller was
configured to handle external master accesses.
AT[0:3] 3 High O Address Type —Driven by the MPC823e along with
the address when it owns the external bus. It provides
additional information about the address on the
current transaction.
I Used only for testing purposes.
RSV
1 Low O Reservation Transfer —Driven by the MPC823e
along with the address when it owns the external bus.
It provides additional information about the address
on the current transaction.
I Used only for testing purposes.
PTR
1 Low O Program Trace —Driven by the MPC823e along with
the address when it owns the external bus. It provides
additional information about the address on the
current transaction.
I Used only for testing purposes.

Motorola MPC823e Specifications

General

Brand	Motorola
Model	MPC823e
Category	Computer Hardware
Language	English