TMP89FS60 datasheet(376/410 Pages) TOSHIBA

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Page 362

22. Serial PROM Mode

22.12 Security

TMP89FS60

RA002

22.12.3Option codes

If a specified option code is placed at a specified address inside the interrupt vector area, whether password

string authentication is performed or not when executing the flash memory erase command and whether the

security program is checked or not when starting OCD can be designated.

- Erase password free code EPFC_OP (0xFFFA)

If changes are frequently made to a program during software development, there are cases in which

a password may get lost. In this case, you can cancel the password string authentication of the flash

memory erase command (0xF0) by setting the erase password free code (EPFC_OP). EPFC_OP is

assigned to 0xFFFA in the vector area. Allocate 0xFF to this EPFC_OP to cancel the password string

of the flash memory erase command (0xF0).

It is recommended that the password string authentication of the flash memory erase command

(0xF0) be enabled during mass production by allocating data other than 0xFF to EPFC_OP.

Only Chip Erase can cancel the password string authentication by using the flash memory erase

command. If Sector Erase is executed with EPFC_OP set to 0xFF, the TMP89FS60 goes into an idle

state. Commands other than the flash memory erase command cannot cancel the password string

authentication.

- OCD security program free code DAFC_OP (0xFFFB)

With the TMP89FS60, you can enable the security program to prevent illegal access attempts by a

third party. If the security program is enabled, restrictions are imposed on operation commands

related to memory access, and the startup of OCD.

The security program should be usually enabled at the time of shipment. If there is the possibility

that the OCD may be used by keeping the contents of memory intact, it is possible to directly start the

OCD by setting the OCD security program free code (DAFC_OP) and thereby skipping the security

program check (the password string authentication, however, is still required).

DAFC_OP is assigned to 0xFFFB in the vector area. To skip the security program check at the

startup of the OCD, assign 0xFF to DAFC_OP. In this case, the security program check is not per-

formed, and the OCD can be started by performing only the password string authentication.

If DAFC_OP is not 0xFF, whether the OCD can be used or not is determined by the status of the

security program. If the OCD is started with the security program enabled, the TMP89FS60 stops

communication and goes into an idle state. To use the OCD when the TMP89FS60 is in this idle

state, Chip Erase must be executed for flash memory by using the flash memory erase command

(0xF0). If the security program is disabled, the OCD can be started by performing only the password

string authentication.

Table 22-22 Option Codes

Symbol

Function

Address

Set value

EPFC_OP

Password string authentication when the flash

memory erase command is executed

0xFFFA

0xFF : The password string authentication is

skipped (only PNSA and PCSA are authenticated).

Other than 0xFF: The password string, PNSA, and

PCSA are authenticated.

DAFC_OP

Security program check when the OCD is

started

0xFFFB

0xFF: The security program check is skipped.

Other than 0xFF: The security program check is per-

formed.

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