38D2 datasheet(72/136 Pages) RENESAS

72 / 136 page

Rev.3.02

Apr 10, 2008

Page 72 of 131

REJ03B0177-0302

38D2 Group

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 70 for details about the Boot ROM area.

Normal microcompu ter mo de is e n t e red 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 and the CNVSS pin high after

pulling the P32/TxD2 pin and 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 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.

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

70 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.

Fig 70. Block diagram of built-in flash memory

Data block A:

1K bytes

Block 1: 26K bytes

Block 0: 32 K bytes

FFFF16

800016

180016

140016

100016

User ROM area

Data block B:

1K bytes

SFR area

Internal RAM area

(2K bytes)

FFFF16

100016

0FFF16

0FE016

083F16

004016

000016

FFFF16

F00016

Boot ROM area

4K bytes

SFR area

Internal flash memory area

(60K bytes)

RAM

Notes1: The boot ROM area can be rewritten

in a parallel I/O mode. (Access to

except boot ROM area is disabled.)

2: To specify a block, use the maximum

address in the block.

3: The QzROM version has the reserved

ROM area. Note the difference of the

area.

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