M32C83T datasheet(71/527 Pages) RENESAS

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6. Processor Mode

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6. Processor Mode

NOTE

M32C/83T can be used in single-chip mode.

M32C/83T cannot be used in memory expansion mode and microprocessor mode.

6.1 Types of Processor Mode

Single-chip mode, memory expansion mode, or microprocessor mode can be selected as processor mode.

Pin functions, memory map and accessible space vary depending on the selected processor mode.

6.1.1 Single-chip Mode

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

All I/O ports can be used.

6.1.2 Memory Expansion Mode

In memory expansion mode, both external memory space and internal memory space can be accessed .

Some pins function as pins for bus control signals. The BYTE pin and register settings determine how

many pins are assigned for these pin functions. Refer to 7. Bus for details.

6.1.3 Microprocessor Mode

In microprocessor mode, SFR, internal RAM and external memory space can be accessed. Internal ROM

cannot be accessed.

Some pins function as pins for bus control signals. The BYTE pin and register settings determine how

many pins are assigned for these pin functions. (Refer to 7. Bus for details.)

6.2 Setting Processor Mode

The processor mode is set by the combination of CNVSS pin and the PM01 to PM00 bit settings in the PM0

If the PM01 to PM00 bits are rewritten, the mode corresponding to the PM01 to PM00 bits is selected

regardless of CNVSS pin level.

Do not change the PM01 to PM00 bits when the PM02 to PM07 bits in the PM0 register are being rewritten.

Do not enter microprocessor mode while the CPU is executing a program in the internal ROM . Do not enter

single-chip mode while the CPU is executing a program in an external memory space.

Figures 6.1 and 6.2 show the PM0 register and PM1 register. Figure 6.3 shows a memory map in each

processor mode.

6.2.1 Applying VSS to CNVSS Pin

The microcomputer enters single-chip mode after reset. Set the PM01 to PM00 bits to "012" (memory

expansion mode) to switch to memory expansion mode after the microcomputer starts operating.

6.2.2 Applying VCC to CNVSS Pin

The microcomputer enters microprocessor mode after reset.

When using the flash memory version, apply VCC to P55 (HOLD) as well as to the CNVSS.

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