M16C62N Datasheet, PDF (161/213 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

CPU Rewrite Mode (Flash Memory Version)
Mitsubishi microcomputers
M16C / 62N Group (80-pin)
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
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 1.28.1 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 1.28.1 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 (When
rewriting the user ROM area in boot mode, bit 5 of the flash memory control register 0 must be set to “1”.
Write to this bit only when executing out of an area other than the internal flash memory).
Block Address
Block addresses refer to an 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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