M68HC12A4EVB データシートの表示（PDF） - Freescale Semiconductor

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M68HC12A4EVB

How to Use the MC68HC812A4 in Special Expanded Narrow Mode Using the M68HC12AEVB

Freescale Semiconductor 

Freescale Semiconductor, Inc.

Engineering Bulletin

Hardware Setup

Setting up the A4EVB in special expanded narrow mode requires

modifying the evaluation board.

Follow these steps to make the modification:

• When setting up the evaluation board, turn off the power to the

A4EVB.

• Jumpers W42 and W34 should be shunted between pins 1 and 2.

W30 should be left floating or pulled out.

• Remove the 74HC32 chip from U3.

• Make a wire jumper from pin 2 on U3 socket to pin 3. This will

make a direct connection from the RAM-CS signal to

RAM-MSB-CS. Chip enable (CE) on pin 22 will have a direct

connection to chip select header W11.

• Select CSP0 by shunting W11-8 between pin 2 and pin 3. CSP0

is enabled from reset and should be used to test the application

program properly.

• Insert RAM chip in socket U6B. Notice that U6A does not have

address line 0 routed, and it is used for expanded wide mode. On

the other hand, U6B does have address line 0 routed directly and

is designed for the use of expanded narrow mode.

• When memory paging is enabled, the EVB includes the footprint

for a 28- and 32-pin RAM footprint. Address lines 16 and 18 are

hardwired to U6B. However, address line 17 needs to be

configured via jumper header W12 by shunting pin 3 and pin 4.

EB350

2

MOTOROLA

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