
Rev.2.00
May 28, 2004
page 57 of 100
38C2 Group (A Version)
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 Processing
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 control
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 standard se-
rial 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 operat-
ing 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 pro-
gram 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 control 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
M38C29FFA
100016
100016
800016
FFFF16
F00016
FFFF16
BSEL=0
BSEL=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