
8-2
G2 PowerPC Core Reference Manual
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MOTOROLA
Signal Groupings
Data arbitration signals—The G2 core uses these signals to arbitrate for data bus
mastership of the 60x data bus.
Data transfer signals—These signals, consisting of the data bus, data parity, and data
parity error signals, are used to transfer the data and to ensure the integrity of the
transfer.
Data transfer termination signals—Data termination signals are required after each
data beat in a data transfer. In a single-beat transaction, the data termination signals
also indicate the end of the tenure. In burst accesses, the data termination signals
apply to individual beats and indicate the end of the tenure only after the final data
beat. They also indicate whether a condition exists that requires the data phase to be
repeated.
Output enable signals—These output signals indicate that the corresponding outputs
of the G2 core are driving, provided the corresponding high-impedance control
signal is also asserted.
High-impedance control signals—These input signals (static) enable the operation
of the output-enable signals.
Input enable signals—When these input signals are asserted, it indicates that they
expect to receive valid data into the core.
In addition, there are many other signals on the G2 core that control and affect other aspects
of the device, aside from the bus protocol. They are as follows:
System status signals—These signals include the external interrupt signal, the
critical interrupt signal (G2_LE only), checkstop signals, and both soft- and
hard-reset signals. These signals are used to interrupt and, under various conditions,
to reset the core.
Reset configuration signals—These signals are sampled while core_hreset is
asserted and they control certain modes of operation.
JTAG/COP interface signals—The JTAG (IEEE 1149.1) interface and common
on-chip processor (COP) unit provides a serial interface to the system for
performing monitoring and boundary tests.
Processor status—These signals include the memory reservation signal, machine
quiesce control signals, time base enable signal, and core_tlbisync signal.
Debug control—These signals are implemented to control debug features of the
PowerPC architecture with respect to the G2 and G2_LE cores.
Clock signals—These signals provide for system clock input and frequency control.
Test interface signals—Signals like address matching, combinational matching, and
watchpoint are used in the G2_LE for production testing.
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