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22.12.3
Option 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.
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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 TMP89FH46L goes into an idle
state. Commands other than the flash memory erase command cannot cancel the password string au-
thentication.
-
OCD security program free code DAFC_OP (0xFFFB)
With the TMP89FH46L, 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 performed, 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 TMP89FH46L stops
communication and goes into an idle state. To use the OCD when the TMP89FH46L 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 au-
thentication.
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 star-
ted
0xFFFB
0xFF: The security program check is skipped.
Other than 0xFF: The security program check is per-
formed.
TMP89FH46L
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