M306H2FCFP datasheet(21/251 Pages) RENESAS

21 / 251 page

Rev. 1.0

SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

with DATA ACQUISITION CONTROLLER

MITSUBISHI MICROCOMPUTERS

M306H2FCFP

2.4 Processor Mode

(1) Types of Processor Mode

Processor mode can be used at microprocessor mode.

One of three processor modes can be selected:single-chip mode and memory expansion mode.The

functions of some pins,the memory map,and the access space differ according to the selected proces-

sor mode.

• Single-chip mode

In single-chip mode,only internal memory space (SFR,internal RAM,and internal ROM)can be

accessed.Ports P0 to P10 can be used as programmable I/O ports or as I/O ports for the internal

peripheral functions.

• Memory expansion mode

In memory expansion mode,external memory can be accessed in addition to the internal memory

space (SFR,internal RAM,and internal ROM).

In this mode,some of the pins function as the address bus,the data bus,and as control signals.The

number of pins assigned to these functions depends on the bus and register settings.(See "Bus

Settings " for details..)

(2) Setting Processor Modes

The processor mode is set using the processor mode bits (bits 1 and 0 at address

000416).Do not set the processor mode bits to "102 " and "112 ".

Changing the processor mode bits selects the mode.Therefore,

never change the processor mode bits when changing the contents of other bits.

• Applying VSS to CNVSS pin

The microcomputer begins operation in single-chip mode after being reset.Memory expansion mode

is selected by writing "012 " to the processor mode is selected bits..

Figure 2.4.1 shows the processor mode register 0 and 1.

Figure 2.4.2 shows the memory maps applicable for each of the modes when memory area dose not

be expanded (normal mode).

Note : Microprocessor mode cannot be used.

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