Motorola M68CPU32BUG Manuel d'utilisateur Page 17

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HARDWARE PREPARATION AND INSTALLATION
M68332BCC/D 2-7 MOTOROLA
REV 1
2.3.3 EPROM Chip Select Header (J3)
When BCC power is applied or reset occurs, the MC68332 MCU device resets itself and
downloads the program in EPROM (U1 & U2). The EPROM contains the boot program. Use the
three-pin jumper header J3 (shown below) to disable the BCC on-board EPROM. The BCC is
shipped from the factory with the EPROM connected to the MCU bootstrap chip select pin
(
CSBOOT
) via a cut-trace short on the bottom of the BCC PCB between pins 1 and 2. A
fabricated jumper is also installed between pins 1 and 2. To boot from a program stored in
memory located in the target system, cut this trace, move the jumper to pins 2 and 3, and connect
CSBOOT
to the target system via P2, pin 25. Cutting the cut-trace short and moving the
fabricated jumper to pins 2 and 3, removes U1 & U2 from the BCC memory map. Refer to the
BCC schematic diagram for more detail on
CSBOOT
signal wiring.
2
1
J3
3
P2
25
64-Pin Expansion Connector
112
U5
MC68332 MCU
U1
CS
OE/VPP
27C512
22
20
CSBOOT
+5V
Fabricated Jumper
U2
CS
OE/VPP
27C512
GND
22
20
CAUTION
Do not connect the jumper between pins 2 and 3 before removing the cut-trace
short between pins 1 and 2. Installing the jumper before the cut-trace short is
removed connects +5Vdc to (
CSBOOT
). If +5Vdc is shorted to (
CSBOOT
)
the MCU may be damaged.
NOTE
If the cut-trace short on jumper header J3 is cut, the fabricated jumper must be
reinstalled on J3 pins 1 and 2 to return the BCC to its default setting.
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