M38862EDFS View Datasheet(PDF) - MITSUBISHI ELECTRIC

Part Name

Description

Manufacturer

M38862EDFS

SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

MITSUBISHI ELECTRIC  

MITSUBISHI MICROCOMPUTERS

3886 Group

SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

PROCESSOR MODE

Single-chip mode, memory expansion mode, and microprocessor

mode in the M38867M8A/E8A can be selected by changing the

contents of the processor mode bits (CM0 and CM1 : b1 and b0 of

address 003B16). In memory expansion mode and microprocessor

mode, memory can be expanded externally through ports P0 to

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

and become bus pins.

Table 15 Port functions in memory expansion mode and

microprocessor mode

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 and P31 function only as output pins

(except that the port latch cannot be read).

P32 is the ONW input pin.

P33 is the RESETOUT output pin. (Note)

P34 is the φ output pin.

P35 is the SYNC output pin.

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

put pin.

Note : If CNVSS is connected to VSS, the microcomputer goes to single-

chip mode after a reset, so that this pin cannot be used as the

RESETOUT output pin.

(1) Single-chip mode

Select this mode by resetting the microcomputer with CNVSS con-

nected 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.

However, do not set this mode in the M38869M8A/MCA/MFA and

the flash memory version.

(3) Microprocessor mode

Select this mode by resetting the microcomputer with CNVSS con-

nected to VCC, or by setting the processor mode bits to “10” in

software with CNVSS connected to VSS. In microprocessor mode,

the internal ROM is no longer valid and external memory must be

used.

Do not set this mode in the M38869M8A/MCA/MFA and the flash

memory version.

000016

000816

004016

SFR area

Internal RAM

reserved area

000016

000816

004016

SFR area

Internal RAM

reserved area

XXXX16*

XXXX16*

YYYY16*

Internal ROM

FFFF16

FFFF16

Memory expansion mode

Microprocessor mode

The shaded area are external memory area.

*: XXXX16 indicates the last address of internal RAM.

YYYY16 indicates the first address of internal ROM.

Fig. 62 Memory maps in various processor modes

b7

b0

CPU mode register

(CPUM : address 003B16)

Processor mode bits (CM1, CM0)

b1 b0

0 0: Single-chip mode

0 1: Memory expansion mode (Note)

1 0: Microprocessor mode (Note)

1 1: Not available

Stack page selection bit

0: 0 page

1: 1 page

Note: This is not available for the products except

M38867M8A/E8A.

Fig. 63 Structure of CPU mode register

61

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