Texas Instruments TMS320x2833 series

2.3.2 Password Match Flow
Start
Yes
No
Yes
No
Deviceunsecure
Usercanaccess
on-chipsecure
memory
Devicepermanentlysecured
CPUaccessislimited.
Devicecannotbedebugged
orreprogrammed.
DodummyreadofPWL
0x33FFF8 − 0x33FFFF
KEYregisters=allones
Correct
password?
ArePWL=
allFs?
ArePWL=
allzeros?
Devicesecureafter
resetorruntime
No
Yes
Writethepasswordto
KEYregisters
0x000AE0 0x000AE7
(A)
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www.ti.com Incorporating Code Security in User Applications
Password match flow (PMF) is essentially a sequence of eight dummy reads from password locations
(PWL) followed by eight writes to KEY registers.
Figure 2-2 shows how the PMF helps to initialize the security logic registers and disable security logic.
Figure 2-2. Password Match Flow (PMF)
A The KEY registers are EALLOW protected.
SPRUFB0C – September 2007 – Revised May 2009 Code Security Module (CSM) 33
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