7641 datasheet(74/138 Pages) RENESAS

74 / 138 page

7641 Group

Rev.4.00

Aug 28, 2006

page 74 of 135

REJ03B0191-0400

PROCESSOR MODE

Single-chip mode, memory expansion mode, and microprocessor

mode which is only in the mask ROM version can be selected by

using the Processor Mode Bits of CPU mode register A (bits 0 and

1 of address 000016). In the memory expansion mode and micro-

processor mode, a memory can be expanded externally via ports

P0 to P3. In these modes, ports P0 to P3 lose their I/O port func-

tions and become bus pins.

The port direction registers corresponding to those ports become

external memory areas.

Fig. 69 Memory maps in processor modes other than single-

chip mode

(1) Single-chip mode

Select this mode by resetting the MCU with CNVSS connected to

VSS.

(2) Memory expansion mode

Select this mode by setting the Processor Mode Bits (b1, b0) to

“01” in software with CNVSS connected to VSS. This mode enables

external memory expansion while maintaining the validity of the in-

ternal ROM.

(3) Microprocessor mode

Select this mode by resetting the MCU with CNVSS connected to

VCC, or by setting the Processor Mode Bits (b1, b0) to “10” in soft-

ware with CNVSS connected to VSS. In the microprocessor mode,

the internal ROM is no longer valid and an external memory must

be used.

Do not set this mode in the flash memory version.

Port Name

Port P0

Port P1

Port P2

Port P3

Function

Outputs low-order 8 bits of address.

Outputs high-order 8 bits of address.

Operates as I/O pins for data D7 to D0 (including

instruction code).

P30 is the RDY input pin.

P31 and P32 function only as output pins

P33 is the DMAOUT output pin.

P34 is the

φOUT output pin.

P35 is the SYNCOUT output pin.

P36 is the WR output pin, and P37 is the RD out-

put pin.

P40 is the EDMA pin.

Table 9 Port functions in memory expansion mode and

microprocessor mode

Port P4

800016

047016

000016

FFFF16

000816

001016

Internal RAM

SFR area

007016

Internal ROM

M37641M8

SFR area

Memory expansion modeMicroprocessor mode

The shaded areas are external areas.

Internal RAM

SFR area

047016

000016

FFFF16

000816

001016

007016

800016

0A7016

000016

FFFF16

000816

001016

007016

100016

Reserved area

M37641F8

Internal RAM

Internal ROM

SFR area

Memory expansion mode

The shaded areas are external areas.

SFR area

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