TC1796
System Units (Vol. 1 of 2)
Program Memory Unit
User’s Manual
7-29
V2.0, 2007-07
PMU, V2.0
The protection configuration bits that are located in the first two bytes of the UCBs
determine the requested protection configuration as it is defined for bits [15:0] of the
Flash Protection Configuration registers PROCON0, PROCON1, and PROCON2. When
a read/write protection has been installed for an user configuration block, the content of
its first two bytes is copied into the corresponding Flash Protection Configuration
register.
UCB Configuration, Confirmation and Activation
In order to set up a UCB correctly, several steps must be done to avoid incorrect and
inoperable UCB contents and, as a result, unrepairable read/write protection.
There are three main tasks to execute for UCB setup:
1.
Configuration of a UCB
This step includes the programming of the first page of a UCB by executing a User
Configuration Page command. This first page determines the protection type and the
two 32-bit keywords. Unused bytes in the first page of the UCB must be programmed
with 00
H
.
2.
Confirmation of the Keywords
The 32-bit confirmation code word, which is located in the third page of a UCB,
should be programmed only after a check of the correct programming of the two
32-bit keywords. Reason: wrong keywords in a UCB can never be retrieved (because
UCBs are not readable), and a confirmed read or write protection cannot be disabled
and changed anymore when the password check (see
) always fails.
The check for correct keywords in a UCB requires to execute a reset operation (e.g.
software reset) after the configuration has been setup as described under point 1.
After the reset, the protection is not fully activated because the confirmation code in
UCB2
UCP8
A000 0800
H
[1:0]
Protection configuration bits (content as
defined for PROCON2)
A000 0808
H
[9:8]
Copy of bytes [1:0]
–
others
Must be programmed to 00
H
UCP9
–
all
This page is reserved for future
purposes; must be programmed to 00
H
UCP10
A000 0600
H
[3:0]
32-bit confirmation code: 8AFE15C3
H
A000 0608
H
[11:8]
Copy of 32-bit confirmation code
–
others
Must be programmed to 00
H
UCP11
–
all
This page is reserved for future
purposes; must be programmed to 00
H
Table 7-16
Layout of User Configuration Blocks
(cont’d)
UCB
Page
Address
Byte(s)
Content