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TMS320F280039C: DCSM Zone1/2 GRABRAMx/GRABSECTx Bits configuration

Part Number: TMS320F280039C

Based on the TRM.Table5-1 description, if both Zone1 and Zone2's GRABRAMx/GRABSECTx Bits is config to 11, then RAM block/Flash Sector inaccessible if either of the zone is secure (CSM passwords are programmed). Never leave these values as default (11), if CSM passwords are programmed for even one zone.

My question : 

1. What meaning of "either of the zone is secure (CSM passwords are programmed)" ? If I config both Zone1 and Zone2's GRABRAMx/GRABSECTx Bits is config to 11, and I programmed CSM passwords, then the RAM/FLASH cannot be access even if I am not lock any Zone(config DCSM_Zx_REGS.Zx_CR.FORCESEC)?

2. In the TRM of TMS280025C Table 3-16, when both Zone1 and Zone2's GRABRAMx/GRABSECTx Bits is config to 11, the description is “RAM block/Flash Sector is unsecure when both
of the zones are UNLOCKED, otherwise memory region is inaccessible if either of the two zones are LOCKED”. The protection logic for 280025 and 280039 in this part are same?

  • Hi Liu Liu,

    1. If the Zone is unlocked/unsecured, the values in the GRABSECT/GRABRAM fields will have no effect. If a zone is locked and it's GRABSECT/GRABRAM field contain a "11", the corresponding memory region will be completely inaccessible.

    2. This is correct.

    Thank you,

    Luke

  • 1. If Zone1 GRABRAMx and Zone2 GRABRAMx is config to {2‘01,2’b11}, based on Table5-1, the RAM belongs to Zone1. If Zone1 is unlocked, and Zone2 is locked, can this RAM be accessible?If both zone1 and zone2 is locked, can this RAM be accessible by program in zone1?

    2. If Zone1 GRABRAMx and Zone2 GRABRAMx is config to {2‘01,2’b10}, based on Table5-1, the RAM belongs to Zone1. If Zone1 is unlocked, and Zone2 is locked, can this RAM be accessible?If both zone1 and zone2 is locked, can this RAM be accessible by program in zone1?

  • Hi Liu Liu,

    If a zone is locked and it's GRABRAM bits are set to 11, the corresponding memory region will be inaccessible in all cases. Otherwise all of the same rules described in the TRM still apply.

    --Luke