60X Signals - Motorola PowerQUICC II MPC8280 Series Reference Manual

Chapter 7

60x Signals

This chapter describes the MPC8280 processor's external signals. It contains a concise
description of individual signals, showing behavior when a signal is asserted and negated,
when the signal is an input and an output, and the differences in how signals work in
external-master or internal-only configurations.
A bar over a signal name indicates that the signal is active low–
for example, ARTRY (address retry) and TS (transfer start).
Active-low signals are referred to as asserted (active) when
they are low and negated when they are high. Signals that are
not active-low, such as TSIZ[0–3] (transfer size signals) and
TT[0–4] (transfer type signals) are referred to as asserted when
they are high and negated when they are low.
The 60x bus signals used with MPC8280 are grouped as follows:
• Address arbitration signals—In external arbiter mode, MPC8280 uses these signals
to arbitrate for address bus mastership. The MPC8280 arbiter uses these signals to
enable an external device to arbitrate for address bus mastership.
• Address transfer start signals—These signals indicate that a bus master has begun a
transaction on the address bus.
• Address transfer signals (address bus)—These signals are used to transfer the
address.
• Transfer attribute signals—These signals provide information about the type of
transfer, such as the transfer size and whether the transaction is single, single
extended, bursted, write-through or cache-inhibited.
• Address transfer termination signals—These signals are used to acknowledge the
end of the address phase of the transaction. They also indicate whether a condition
exists that requires the address phase to be repeated.
• Data arbitration signals—The MPC8280, in external arbiter mode, uses these signals
to arbitrate for data bus mastership. The MPC8280 arbiter uses these signals to
enable an external device to arbitrate for data bus mastership.
MOTOROLA
Freescale Semiconductor, Inc.
NOTE
Chapter 7. 60x Signals
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