Texas Instruments C2000

Code Security Module (CSM)
C2000 Microcontroller Workshop - System Design 12 - 13
CSM Caveats

Never program all the PWL’s as 0x0000
 Doing so will permanently lock the CSM
 Flash addresses 0x3F7F80 to 0x3F7FF5,
inclusive, must be programmed to 0x0000 to
securely lock the CSM
 Remember that code running in unsecured
RAM cannot access data in secured memory
 Don’t link the stack to secured RAM if you have
any code that runs from unsecured RAM
 Do not embed the passwords in your code!
 Generally, the CSM is unlocked only for debug
 Code Composer Studio can do the unlocking
CSM Password Match Flow
Flash device
secure after
reset or runtime
Do dummy reads of PWL
0x3F 7FF8 – 0x3F 7FFF
Start
Device permanently locked
Device unlocked
User can access on-
chip secure memory
Write password to KEY registers
0x00 0AE0 – 0x00 0AE7
(EALLOW) protected
Correct
password?
Is PWL =
all Fs?
Is PWL =
all 0s?
Yes
Yes
Yes
No
No
No