TC1784
Program Memory Unit (PMU)
User´s Manual
5-64
V1.1, 2011-05
PMU, V1.47
5.6.5
Read and Write Protection
For an overview please refer to
In general, three user levels are supported for installation of protection configuration, and
three different types of protection can be assigned to the user levels as follows:
1. User 0: This is the master user. He is able to install read protection for the whole
Flash (with or without DFlash). Additionally or alternatively, he can install sector
specific write protection. User 0 controls the User Configuration Block UCB0 in the
configuration sector and defines his keywords in UCB0.
2. User 1 is able to install sector specific write protection, with lower priority than user 0.
User 1 controls the UCB1 in config sector and defines his keywords in UCB1.
3. User 2 is able to install sector specific OTP protection with ROM functionality.
Sectors with ROM functionality are locked for ever and are never re-programmable.
Keywords for temporary disabling the protection are therefore not necessary. User 2
(who might be identical to user 0 or user 1) controls the UCB2.
Any installation of protection will become active only after next reset.
5.6.5.1
Read Protection
When read protection is installed and active, read accesses to the Flash memory are
disabled and suppressed, if the program execution does not start in internal Flash after
reset. Thus Flash read accesses by instructions fetched from other memory but internal
Flash are initially blocked. The read protection is characterized by the following
definitions:
•
The read protection is installed, if the read protection configuration is programmed
(thus the read protection is configured) and confirmed in the User Configuration Block
of user 0 (UCB0); the installed read protection is indicated in the FSR register by
RPROIN-bit and in PROCON0 by RPRO-bit. If read protection is configured but not
confirmed, only RPRO is set after next reset.
•
The Data Flash is only excluded from read protection, if the bit DFEXPRO is set
additionally to the RPRO-bit in register PROCON0.
•
The read protection is active, when it is installed and not temporarily disabled with
password protected command sequence ‘Disable Read Protection’; this state is
shown with RPA-bit in configuration register FCON.
•
If read protection is active (RPA=1), also a global write protection for the whole Flash
array is activated. The Data Flash is only excluded from the global write protection, if
the bit DFEXPRO is set additionally to the RPRO-bit in register PROCON0. Flash
erase/program commands are generally disabled and not executed. But accesses to
registers and command cycles (write cycles) to the state machine are enabled
(necessary for the disable command sequence).
•
If read protection is active, the Flash read accesses are controlled with the disable
bits DCF (disable code fetch) and DDF (disable data fetch) in FCON register. After
reset, these bits are set if the user program start is not executed from internal Flash
Summary of Contents for TC1784
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