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BSL Protection Features

  • Prohibits commands allowing direct or indirect data access without BSL password

  • Password = 16 x 16-bit ISR vector addresses

  • Changing ISR vectors changes password

  • Unprotected commands like mass erase and RX password are always allowed

  • Applying the RX password command and proper password unlocks all protected commands

  • After mass erase all password bits are = 1

  • F2xx BSL can be totally disabled

  • F2xx BSL erases entire Flash memory when invalid password is supplied (feature can be disabled)

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BSL Password Details

The password is the 16x16-bit interrupt vector values Max Code Crack Duration:

2256

combinations ×

44 bytes×8 bits 9600 baud

134e66 years

  • Enhance security by initializing unused int vectors

  • In IAR C, use ”__root” and absolute variable placement

/ / P r o g r a m u n u s e d i n t e r r u p t v e c t o r s r o o t c o n s t i n t B S L P W 1 @ 0 x f f e 0 = 0 x 1 2 3 4 ; / / P r o g r a m u n u s e d i n t e r r u p t v e c t o r s __ r o o t c o n s t i n t B S L P W 1 @ 0 x f f e 0 = 0 x 1 2 3 4 ;

_ _ r o o t c o n s t i n t B S L P W 2 @ 0 x f f e 2 = 0 x 5 6 7 8 ; r o o t c o n s t i n t B S L P W 2 @ 0 x f f e 2 = 0 x 5 6 7 8 ; __ __

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