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Under
development
Preliminary Specifications REV.B3
Specifications in this manual are tentative and subject to change.
Mitsubishi Microcomputers
M32C/83 group
SINGLE-CHIP 16/32-BIT CMOS MICROCOMPUTER
CPU Rewrite Mode (Flash Memory Version)
384
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 1.33.3 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 1.33.3 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.
Outline Performance of CPU Rewrite Mode
In the CPU rewrite mode, the CPU erases, programs and reads the internal flash memory as instructed by
software commands. Operations must be executed from a memory other than the internal flash memory,
such as the internal RAM.
When the CPU rewrite mode select bit (bit 1 at address 037716) is set to “1”, transition to CPU rewrite mode
occurs and software commands can be accepted.
In the CPU rewrite mode, write to and read from software commands and data into even-numbered ad-
dress (“0” for byte address A0) in 16-bit units. Always write 8-bit software commands into even-numbered
address. Commands are ignored with odd-numbered addresses.
Use software commands to control program and erase operations. Whether a program or erase operation
has terminated normally or in error can be verified by reading the status register.
Figure 1.34.1 shows the flash memory control register 0.