firmware code protection on a C5515 DSP using external SPI EEPROM ?


Not entirely sure if this is possible however I'm willing to hear all suggestions. Basically we're looking at a way to protect our firmware code from reading and/or modification once it's been loaded into the external SPI EEPROM. Our custom designed C5515 based DSP board uses the internal boot-loader to load the firmware code from the external EEPROM via SPI. Is there a way to prevent reading of the code, say by encrypting the code and decrypting it with the boot-loader, then preventing JTAG access to the DSP by blowing a DSP fuse or something like that ? Otherwise, the internal ROM can it be used to program the DSP with the firmware (once we have a stable version etc.) ? Any other suggestion perhaps more practical ?

Thanks in advance for any info.

Regards, Mike

11 Replies

  • In reply to M MAR:


    I just downloaded the Datasheet "Using the TMS320C5515/14/05/04 Bootloader" (SPRABD7A–June 2010–Revised January 2012) from the TI-homepage. On page 2 it is mentioned that reauthoring is supported for NOR, NAND, 16-bit SPI EEPROM, I2C EEPROM, and MMC/SD. With the 24-bit SPI serial flash both secure and unsecure images are possible, but no reauthoring.