103
7641 Group
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
MITSUBISHI MICROCOMPUTERS
Fig. 88 Block diagram of built-in flash memory
(1) CPU Rewrite Mode
In CPU rewrite mode, the internal flash memory can be operated
on (read, program, or erase) under control of the Central Process-
ing Unit (CPU).
In CPU rewrite mode, only the User ROM area shown in Figure 88
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 con-
trol program must be transferred to internal RAM area to be
executed 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 stan-
dard serial I/O mode becomes unusable.)
See Figure 88 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 P36 (CE) pin high,
the P81 (SCLK) pin high, the CNVSS pin high, the CPU starts oper-
ating using the control program in the Boot ROM area. This mode
is called the “Boot” mode.
Block Address
Block addresses refer to the maximum address of each block.
These addresses are used in the block erase command.
E00016
User ROM area
4 Kbytes
FFFF16
Boot ROM area
Notes 1: The Boot ROM area can be rewritten in only parallel I/O mode. (Access to any other
areas is inhibited.)
2: To specify a block, use the maximum address in the block.
Parallel I/O mode
CPU rewrite mode, standard serial I/O mode
BSEL = “L”
BSEL = “H”
User area / Boot area select bit = “0”
User area / Boot area select bit = “1”
C00016
Block 1 : 8 Kbytes
Block 2 : 16 Kbytes
Block 0 : 8 Kbytes
800016
F00016
FFFF16
E00016
User ROM area
4 Kbytes
FFFF16
Boot ROM area
C00016
Block 1 : 8 Kbytes
Block 2 : 16 Kbytes
Block 0 : 8 Kbytes
800016
F00016
FFFF16