Engineering Bulletin

Migrating to the MC68HC11F1

EB381

MOTOROLA

13

Figure 9. MC68HC11F1 Non-Multiplexed Bus Example

Memory Map

Example

This example is for connecting an 8- or 16-Kbyte external RAM and a

32-Kbyte external EPROM. See Figure 10.

•

Leave internal RAM at default location ($0000–$03FF).

•

Leave register block at default location ($1000–$105F).

•

Relocate internal EEPROM to address $2E00–$2FFF. This is

done by programming the EE0–EE3 bits in the CONFIG register

($103F) to %0010. You may also need to program the EEON bit

to ensure that the EEPROM is present in the memory map (see

Figure 7).

•

CSPROG comes up enabled in expanded mode. You will need to

program the PSIZA and PSIZB bits in the CSCTL register ($105D)

to set an address range. In this example, PSIZA = 0 and

PSIZB = 1 ($8000–$FFFF). The user may also want to clear the

PSTHA and PSTHB bits in the CSSTRH register ($105C) to

ensure no clock stretch is used. Another option with CSPROG is

the priority regarding CSGEN. This can be programmed using the

GCSPR bit in the CSCTL register.

R/W

E

ADDRESS

68HC11F1

WE

OE

DATA

OE

WE

OE

CSGEN

DATA

DATA

EPROM

ADDRESS

RAM

ADDRESS

CE

CE

CSGPROG

Freescale Semiconductor, Inc.

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