M306V2ME Datasheet, PDF (23/276 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER and ON-SCREEN DISPLAY CONTROLLER

MITSUBISHI MICROCOMPUTERS
M306V2ME-XXXFP
M306V2EEFP
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
and ON-SCREEN DISPLAY CONTROLLER
2.4 Processor Mode
2.4.1 Types of Processor Mode
One of three processor modes can be selected: single-chip mode, memory expansion mode, and micro-
processor mode. The functions of some pins, the memory map, and the access space differ according to
the selected processor mode.
(1) Single-chip mode
In single-chip mode, only internal memory space (SFR, OSD RAM, 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.
(2) Memory expansion mode
In memory expansion mode, external memory can be accessed in addition to the internal memory
space (SFR, OSD RAM, 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 “2.4.3 Bus
Settings” for details.)
(3) Microprocessor mode
In microprocessor mode, the SFR, OSD RAM, internal RAM, and external memory space can be
accessed. The internal ROM area cannot be accessed.
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 “2.4.3 Bus
Settings” for details.)
2.4.2 Setting Processor Modes
The processor mode is set using the CNVSS pin and the processor mode bits (bits 1 and 0 at address
000416). Do not set the processor mode bits to “102”.
Regardless of the level of the CNVSS pin, changing the processor mode bits selects the mode. Therefore,
never change the processor mode bits when changing the contents of other bits. Also do not attempt to
shift to or from the microprocessor mode within the program stored in the internal ROM area.
(1) 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.
(2) Applying VCC to CNVSS pin
The microcomputer starts to operate in microprocessor mode after being reset.
Figures 2.4.1 and 2.4.2 show the processor mode register 0 and 1.
Figure 2.4.3 shows the memory maps applicable for each of the modes.
Rev. 1.0
23