M16CSLASH62M datasheet(238/615 Pages) RENESAS

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CPU Rewrite Mode (Flash Memory Version)

Mitsubishi microcomputers

M16C / 62A Group

SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

1-219

CPU Rewrite Mode

In CPU rewrite mode, the on-chip flash memory can be operated on (read, program, or erase) under control

of the Central Processing Unit (CPU).

In CPU rewrite mode, only the user ROM area shown in Figure 1.25.1 can be rewritten; the boot ROM area

cannot be rewritten. Make sure the program and block erase commands are issued for only the user ROM

area and each block area.

The control program for CPU rewrite mode can be stored in either user ROM or boot ROM area. In the CPU

rewrite mode, because the flash memory cannot be read from the CPU, the rewrite control program must

be transferred to any area other than the internal flash memory before it can be executed.

Microcomputer Mode and Boot Mode

The control program for CPU rewrite mode must be written into the user ROM or boot ROM area in

parallel I/O mode beforehand. (If the control program is written into the boot ROM area, the standard

serial I/O mode becomes unusable.)

See Figure 1.25.1 for details about the boot ROM area.

Normal microcomputer mode is entered when the microcomputer is reset with pulling CNVSS pin low. In

this case, the CPU starts operating using the control program in the user ROM area.

When the microcomputer is reset by pulling the P55 pin low, the CNVSS pin high, and the P50 pin high, the

CPU starts operating using the control program in the boot ROM area. This mode is called the “boot”

mode. The control program in the boot ROM area can also be used to rewrite the user ROM area.

Block Address

Block addresses refer to the maximum even address of each block. These addresses are used in the

block erase command, lock bit program command, and read lock status command.

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