7641 datasheet(103/138 Pages) RENESAS

103 / 138 page

7641 Group

Rev.4.00

Aug 28, 2006

page 103 of 135

REJ03B0191-0400

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

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