Motorola PowerQUICC II MPC8280 Series Reference Manual page 255

Signal
BR 60x bus request—This is an output when an external arbiter is used and an input when an internal
arbiter is used. As an output the MPC8280 asserts this pin to request ownership of the 60x bus.
As an input an external master should assert this pin to request 60x bus ownership from the
internal arbiter.
BG 60x bus grant—This is an output when an internal arbiter is used and an input when an external
arbiter is used. As an output the MPC8280 asserts this pin to grant 60x bus ownership to an
external bus master. As an input the external arbiter should assert this pin to grant 60x bus
ownership to the MPC8280.
ABB 60x address bus busy—(Input/output) As an output the MPC8280 asserts this pin for the duration
of the address bus tenure. Following an AACK, which terminates the address bus tenure, the
MPC8280 negates ABB for a fraction of a bus cycle and than stops driving this pin. As an input
the MPC8280 will not assume 60x bus ownership as long as it senses this pin is asserted by an
external 60x bus master.
IRQ2 Interrupt Request 2—This input is one of the eight external lines that can request (by means of
the internal interrupt controller) a service routine from the core.
TS 60x bus transfer start—(Input/output) Assertion of this pin signals the beginning of a new address
bus tenure. The MPC8280 asserts this signal when one of its internal 60x bus masters (core,
DMA, PCI bridge) begins an address tenure. When the MPC8280 senses this pin being asserted
by an external 60x bus master, it will respond to the address bus tenure as required (snoop if
enabled, access internal MPC8280 resources, memory controller support).
A[0–31] 60x address bus—These are input/output pins. When the MPC8280 is in external master bus
mode, these pins function as the 60x address bus. The MPC8280 drives the address of its
internal 60x bus masters and respond to addresses generated by external 60x bus masters.
When the MPC8280 is in internal master bus mode, these pins are used as address lines
connected to memory devices and controlled by the MPC8280's memory controller.
TT[0–4] 60x bus transfer type—These are input/output pins. The 60x bus master drives these pins during
the address tenure to specify the type of the transaction.
TBST 60x bus transfer burst—(Input/output) The 60x bus master asserts this pin to indicate that the
current transaction is a burst transaction (transfers 4 double words).
TSIZ[0–3] 60x transfer size—These are input/output pins. The 60x bus master drives these pins with a value
indicating the amount of bytes transferred in the current transaction.
AACK 60x address acknowledge—This is an input/output signal. A 60x bus slave asserts this signal to
indicate that it identified the address tenure. Assertion of this signal terminates the address
tenure.
ARTRY 60x address retry—(Input/output) Assertion of this signal indicates that the bus transaction
should be retried by the 60x bus master. The MPC8280 asserts this signal to enforce data
coherency with its internal cache and to prevent deadlock situations.
DBG 60x data bus grant—This is an output when an internal arbiter is used and an input when an
external arbiter is used. As an output the MPC8280 asserts this pin to grant 60x data bus
ownership to an external bus master. As an input the external arbiter should assert this pin to
grant 60x data bus ownership to the MPC8280.
MOTOROLA
Freescale Semiconductor, Inc.
Table 6-1. External Signals
Chapter 6. External Signals
For More Information On This Product,
Go to: www.freescale.com
Description
Signal Descriptions
6-3