7.3.2 Lock Bits (LB) Page Description
This page contains the following information:
• Main block Page Lock Words (PLWs)
• User data page Lock Word (ULWs)
• Debug Lock Word (DLW)
• Mass erase Lock Word (MLW)
• Authentication Access Port (AAP) lock word (ALW)
• Bootloader enable (CLW0)
• Pin reset soft (CLW0)
The words in this page are organized as shown in
Table 7.2 Lock Bits Page Structure on page 128
Table 7.2. Lock Bits Page Structure
127
DLW
126
ULW
125
MLW
124
ALW
122
CLW0
N
PLW[N]
…
…
1
PLW[1]
0
PLW[0]
There are 32 page lock bits per page lock word (PLW). Bit 0 refers to the first page and bit 31 refers to the last page within a PLW.
Thus, PLW[0] contains lock bits for page 0-31 in the main block, PLW[1] contains lock bits for page 32-63 etc. A page is locked when
the bit is 0. A locked page cannot be erased or written.
Word 127 is the debug lock word (DLW). The four LSBs of this word are the debug lock bits. If these bits are 0xF, then debug access is
enabled. Debug access to the core is disabled from power-on reset until the DLW is evaluated immediately before the Cortex-M4 starts
execution of the user application code. If the bits are not 0xF, then debug access to the core remains blocked.
Word 126 is the user page lock word (ULW). Bit 0 of this word is the User Data Page lock bit. Bit 1 in this word locks the Lock Bits
Page. The lock bits can be reset by a device erase operation initiated from the Authentication Access Port (AAP) registers. The AAP is
described in more detail in
6.3.3 Authentication Access Point
. Note that the AAP is only accessible from the debug interface, and can-
not be accessed from the Cortex-M4 core.
Word 125 is the mass erase lock word (MLW). Bit 0 locks the entire flash. The mass erase lock bits will not have any effect on device
erases initiated from the Authenitcation Access Port (AAP) registers. The AAP is described in more detail in
.
Word 124 is the Authentication Access Port (AAP) lock word (ALW) and the four LSBs of this word are the lock bits. If these bits are
0xF, then AAP access is enabled. If the bits are not 0xF, AAP is disabled and it is impossible to access the device through the AAP. Bit
31 of the ALW may be used to allow AAP access under controlled conditions. If bit 31 is set to 1, software running on the device can
unlock AAP access using the MSC_AAPUNLOCKCMD register. If bit 31 is cleared to 0, software will not be able to use MSC_AAPUN-
LOCKCMD to unlock AAP access.
NOTE - locking the AAP completely (including the LSBs and bit 31) is irreversible. Once the
AAP is locked, it will be impossible to perform an external mass erase and the AAP lock cannot be reset.
The only way to pro-
gram the device when the AAP is locked is through a boot loader or by SW already loaded into the FLASH.
Word 122 is configuration word Zero. Bit 2 is the pinresetsoft bit. Bit 1 is the bootloader enable bit.
7.3.3 Device Information (DI) Page
This read-only page holds oscillator and ADC calibration data from the production test as well as an unique device ID. The page is
further described in
.
Reference Manual
MSC - Memory System Controller
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