tmp89fm42 TOSHIBA Semiconductor CORPORATION, tmp89fm42 Datasheet - Page 374

• Manufacturer Part Number: tmp89fm42
• Description: 8 Bit Microcontroller
• Manufacturer: TOSHIBA Semiconductor CORPORATION

22.12 Security
22. Serial PROM Mode
RA002
22.12.3Option codes
Table 22-22 Option Codes
EPFC_OP
DAFC_OP
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.
Symbol
If a specified option code is placed at a specified address inside the interrupt vector area, whether password
- Erase password free code EPFC_OP (0xFFFA)
- OCD security program free code DAFC_OP (0xFFFB)
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).
(0xF0) be enabled during mass production by allocating data other than 0xFF to EPFC_OP.
command. If Sector Erase is executed with EPFC_OP set to 0xFF, the TMP89FM42 goes into an idle
state. Commands other than the flash memory erase command cannot cancel the password string
authentication.
third party. If the security program is enabled, restrictions are imposed on operation commands
related to memory access, and the startup of OCD.
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).
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.
security program. If the OCD is started with the security program enabled, the TMP89FM42 stops
communication and goes into an idle state. To use the OCD when the TMP89FM42 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.
Password string authentication when the flash
memory erase command is executed
Security program check when the OCD is
started
If changes are frequently made to a program during software development, there are cases in which
It is recommended that the password string authentication of the flash memory erase command
Only Chip Erase can cancel the password string authentication by using the flash memory erase
With the TMP89FM42, you can enable the security program to prevent illegal access attempts by a
The security program should be usually enabled at the time of shipment. If there is the possibility
DAFC_OP is assigned to 0xFFFB in the vector area. To skip the security program check at the
If DAFC_OP is not 0xFF, whether the OCD can be used or not is determined by the status of the
Function
Page 360
Address
0xFFFB
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.
0xFF: The security program check is skipped.
Other than 0xFF: The security program check is per-
formed.
Set value
TMP89FM42