SH7041A datasheet(741/923 Pages) RENESAS

741 / 923 page

703

22.6.2

User Program Mode

After setting FWP, the user should branch to, and execute, the previously prepared

programming/erase control program.

As the flash memory itself cannot be read while flash memory programming/erasing is being

executed, the control program that performs programming and erasing should be run in on-chip

RAM or external memory.

Use the following procedure (figure 22.12) to execute the programming control program that

writes to flash memory (when transferred to RAM).

Execute user application

program

Execute programming/

erase control program in RAM

(flash memory rewriting)

Transfer programming/erase

control program to RAM

FWP = 1

(user program mode)

Write FWP assessment program

and transfer program

Figure 22.12 User Program Mode Execution Procedure

Notes: 1. When programming and erasing, start the watchdog timer so that measures can be

taken to prevent program runaway, etc. Memory cells may not operate normally if

overprogrammed or overerased due to program runaway.

2. If an address at which a flash memory register resides is read in the mask ROM or

ZTAT version, the value will be undefined. When a flash memory version program is

used in the mask ROM or ZTAT version, the state of the FWP pin cannot be

determined. A modification must therefore be made to prevent operation of the flash

memory rewrite program.

SH7041A Datasheet(PDF) 741 Page - Renesas Technology Corp