57
38C2 Group
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
MITSUBISHI MICROCOMPUTERS
PRELIMINAR
Y
Notice:
This
is not
a final
specification.
Som
e parametric
limits
are
subject
to
change.
Fig. 61 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 61
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 before it
can be executed.
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 61 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 P41(CE) pin high,
the CNVSS pin high, the CPU starts operating (start address of
program is stored into addresses FFFC16 and FFFD16) using the
control program in the Boot ROM area. This mode is called the
“Boot mode”. Also, User ROM area can be rewritten using the con-
trol program in the Boot ROM area.
Block Address
Block addresses refer to the maximum address of each block.
These addresses are used in the block erase command.
100016
800016
FFFF16
F00016
FFFF16
M38C29FF
100016
100016
800016
FFFF16
F00016
FFFF16
BSEL=0BSEL=1
User ROM area
4 Kbytes
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
User area / Boot area select bit = “0”
Block 1 : 28 Kbytes
User ROM area
4 Kbytes
Boot ROM area
Block 1 : 28 Kbytes
Block 0 : 32 Kbytes
User area / Boot area select bit = “1”
Product name
Flash memory
top address