In-Circuit Emulation Interface
A-4
MC68322 USER’S MANUAL
MOTOROLA
I_RESET
INTERNAL RESET—Output. This signal is used by an emulator to assert the RESET signal.
Typically this signal is connected directly to the MC68000 ICE.
I_HALT
INTERNAL HALT—Output. This signal is used to assert the emulator HALT signal. It should
be connected directly to the M68000 emulator HALT signal.
I_DLEN
ICE DATA LATCH ENABLE—Output. This signal is used by external latches to latch
incoming data before being sent to the emulator.
ICEN
ICE ENABLE—Input. This signal should be asserted during in circuit emulation because it
will force the MC68322 to act as a slave device to an external M68000 processor. It must be
asserted or negated before the negation of RESET and remain that way during operation.
A.2 ICE ADAPTOR BOARD DESIGN
In a typical system, the logic board contains an MC68322 and a PGA connector around the
160-pin QFP MC68322. The PGA connects directly to all the signals of the MC68322. The
user plugs the ICE interface into this PGA connector, which asserts the HI-Z input pin on the
MC68322 on the logic board, thereby forcing it to three-state. With the MC68322
three-stated, the MC68322 ICE on the ICE interface has control of all the signals on the logic
board. The MC68322 ICE takes the place of the MC68322 in the system when the ICE
interface is installed.
Normally, the ICEN input pin on the MC68322 ICE is connected to ground, which disables
the internal core and uses an MC68000 ICE for the processor. For diagnostic purposes, if
ICEN is connected high on the ICE module, then the internal core is used. When an
MC68000 ICE is used, IA27–IA26 to the MC68322 ICE are tied to ground. An MC68000 ICE
can only access the lower 64M of memory, but an MC68020 ICE can be used instead. If an
MC68020 ICE is used, then IA27–IA26 are driven by the MC68020 ICE, which can access
the entire 256M of memory. Figure A-1 illustrates the connection between the ICE interface
and the logic board.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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