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4-24 Copyright © 2003-2007 ARM Limited. All rights reserved. ARM DUI 0224F
4.3.5 Lock Register, SYS_LOCK
The SYS_LOCK register at
0x10000020
locks or unlocks access to the following
registers:
• Oscillator registers, SYS_OSCx
• Reset values for oscillators, SYS_OSCRESETx
• Configuration registers, SYS_CFGDATAx
• Reset control register, SYS_RESETCTL
The control registers cannot be modified while they are locked. This mechanism
prevents the registers from being overwritten accidently. The registers are locked by
default after a reset. Figure 4-10 shows the bit assignment of the register.
Figure 4-10 Lock Register, SYS_LOCK
Table 4-7 describes the PB926EJ-S Lock Register bit assignment.
Table 4-7 Lock Register, SYS_LOCK bit assignment
Bits Access Description
[31:17] Reserved. Use read-modify-write to preserve value.
[16] Read LOCKED, this bit indicates if the control
registers are locked or unlocked:
0 = unlocked
1 = locked.
[15:0] Read/write LOCKVAL, write the value
0xA05F
to unlock
the control registers. Write any other value to
this register to lock the registers.