Protection Strategy & IAP

sergio2 · ‎2003-05-27

Posted on May 28, 2003 at 06:03

sergio2 · ‎2011-05-17

Posted on May 17, 2011 at 11:34

Somebody could recommend me some application note or white paper to learn about the best protection strategy for ST92F120/F

I want to protect the copyright of the firmware inside the flash memory, so it cannot be read by not authorized people, using ST or of third parts tools.

I already made my own IAP routines that, thanks to a communication protocol via RS232, (where the data go encrypted), it allows me to reprogram and verify the sectors Flash1 and Flash2

I want to learn, what I should write and when I should write it in the NVAPR, NVWPR,NVPWD0/1 registers, to achieve that my own IAP doesn't have inconveniences to read and to write in the Flash memory, but the access remains blocked to read the data otherwise

I would also,

previous erasing of the whole flash memory, to be able to reprogram the flash again, using the standard ST9 tools ST9-EPB (ISP)

Thank you for your suggestions

[ Este mensaje fue editado por: Sergio on 27-05-2003 18:40 ]

johanpauvert2 · ‎2011-05-17

Posted on May 17, 2011 at 11:34

You can refer to AN1279 enclosed with this message.

Skywalker

[ This message was edited by: Skywalker on 27-05-2003 23:04 ]

romain2399 · ‎2011-05-17

Posted on May 17, 2011 at 11:34

I want to protect the flash memory, so it cannot be read using ST or of third parts tools.

=> EPB/Test mode tool: you must use a PassWord.

=> ISP mode: you must protect the memory against Access mode from RAM and external memory (NVAPR, APRO bit)

My own IAP doesn't have inconveniences to read and to write in the Flash memory, but the access remains blocked to read the data otherwise

=> You need a code executed in FLASH that will unprotect temporary the FLASH

Be able to reprogram the flash again, using the standard ST9 tools ST9-EPB (ISP)

=> Protection registers cannot be ''erase'', unprotection is only temporary so it will not be possible to remove the protection, have a reset, and have still the memory unprotected => not possible, you must use IAP over all the FLASH, if a reset occur during the process the device is lost.