TC1796
System Units (Vol. 1 of 2)
Program Memory Unit
User’s Manual
7-30
V2.0, 2007-07
PMU, V2.0
the UCB is still not valid but it is already configured. After issuing a Disable Read
Protection or Disable Write Protection command (depending on the configured
protection type) with the expected passwords, the status flag FSR.PROER indicates,
whether password checking was ok or not.
If PROER = 0 after the Disable Read Protection or Disable Write Protection
command, the password check was ok, meaning that the keywords in the UCB are
identical with the passwords that have been transmitted with the command. Now the
32-bit confirmation code word must be still programmed into the third page of the
UCB by the Write User Configuration Page command. Unused bytes of the third page
of the UCB should be programmed with 00
H
. After that operation, the selected
protection is defined to be “installed”.
If PROER = 1 after the Disable Read Protection or Disable Write Protection
command, the password check was negative. In this case (and if the correct
passwords are not known), the related UCB has to be erased again and the UCB
setup must be repeated as described under point 1.
3.
Activation of an Installed Protection
When a read or write protection has been installed, it can only be activated by
executing any reset operation. After this reset operation, an installed protection
becomes “active”.
7.2.7.2
Write and OTP Protection for PFLASH
Write protection is a feature that must be installed by the user of the TC1796 device. In
the delivery state of the TC1796, no write protection is installed meaning that the UCBs
are in erased state. If sector write protection is active for a PFLASH sector, erasing and
programming of this sector is only possible if the corresponding UCB keywords are
known.
OTP write protection can be installed and enabled for a PFLASH sector only once after
the TC1796 delivery state. Write protection configuration for a PFLASH sector can be
modified by erasing and re-programming of the related UCB.
The sector write protection configuration must be initially programmed into one of the
three UCBs by using the Write User Configuration Page command. With this command,
the user determines the PFLASH sector(s) to be write-protected and two 32-bit keywords
which are required to temporarily disable an already installed write protection
configuration or to temporarily disable an active sector write protection. Erasing and
reprogramming of UCB0 or UCB1 can be performed up to 4 times during TC1796 device
lifetime.
As described above on
, sector write protection remains active as long as no
Disable Write Protection command is issued. Within this command sequence, the user
has to identify itself by its passwords and its user level (UL, see command sequence
definition). After the Disable Write Protection command, sector write protection is
temporarily disabled for all sectors that belong to the user. Thereby, disabling of write