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TMS320F28020 locked

Nancy Jean Burkholder
Prodigy 50 points

Other Parts Discussed in Thread: UNIFLASH, TMS320F28020

While programming target flash using a Spectrum Digital XDS510LC JTAG the power supply experienced a glitch that disrupted the download. Afterwards I could no longer connect or download to the processor. 

I installed UniFlash but the tool could not resurrect the device. Further research seems to indicate the part is irreversibly bricked.

Is this the most probable outcome? I will replace the CPU if necessary. I appreciate any suggestions or pointers to other options.

Nancy

Here is the console captured from UniFlash:

[05:09:04] Begin Launching session operation.

[05:09:06] Operation Launching session returned.
[05:09:06] Loaded target configuration from: C:\Users\nancy.burkholder\Documents\F28029.ccxml
[05:09:20] C28xx: Flash Programmer: Warning: The configured device (TMS320F28020), does not match the detected device (). Flash Programming operations could be affected. Please consider modifying your target configuration file.

[05:09:20] C28xx: GEL Output:
Device Calibration not complete, check if device is unlocked and recalibrate.
[05:09:21] C28xx: Erasing Flash memory...

[05:09:21] ERROR >> C28xx: Flash Programmer: Error erasing flash memory. Device is locked or not connected. Operation cancelled

[05:09:21] Flash operation Erase failed on core Spectrum Digital C2000 XDS510LC Emulator/C28xx .
[05:09:41] C28xx: GEL Output:
Device Calibration not complete, check if device is unlocked and recalibrate.
[05:09:41] C28xx: Starting device unlocking...

[05:09:41] ERROR >> C28xx: Flash Programmer: Error unlocking flash memory. Device is still locked

[05:09:41] Flash operation Unlock failed on core Spectrum Digital C2000 XDS510LC Emulator/C28xx .

  • 0
    Guru 192875 points

    Hi Nancy,

    Nancy Jean Burkholder said:
    Is this the most probable outcome? I will replace the CPU if necessary. I appreciate any suggestions or pointers to other options.

    Permanent damage of flash due to power loss during programming is not that likely. However, I would suggest you to perform an erase of the sector that was interrupted during program before you try to re-program.

    Yes, power failure during an erase operation can cause flash bits to get depleted. Over erase of flash cell causes depletion.Depletion means you have removed more of the electrons off of the floating gate than necessary for an erased bit. There is a possibility that some bits are slightly depleted by the end of the erase procedure. Compaction which is performed as a part of erase process can bring the slightly depleted bits back into the erased (non-depleted) state. If the erase process gets interrupted and bits are left in a depleted state it can have an influence during reads of other bits in the flash. This can also influence the erase of other sectors.If there is a power failure during the erase operation, we recommend you to use the depletion recovery function, followed by erase of the sector (that was interrupted)

    The depletion recovery function can be used to bring back the depleted bits back to erased state. This function can be run as many times as required. But. there is no guarantee that this would work if the flash bits are depleted beyond recovery.

    Here's more about Depletion recovery function: http://processors.wiki.ti.com/index.php/C2000_Flash_Common_Issues/FAQs#Depletion

    Regards,

    Gautam

  • 0 in reply to Gautam Iyer
    Prodigy 50 points

    Hi Guatam,

    Thank you for your explanation of depletion. I tried depletion with UniFlash without success. I will proceed with replacing the processor.

    I believe I found the power glitch source. The processor is driving an H-bridge configuration through the PWMs with active low signals. There are no pull-up resistors between the processor and the hex inverter buffer that is in series with the H-bridge driver circuitry. I suspect that these signals are susceptible to noise that could result in both FETs in a leg turning on, thus shorting the power supply. I have observed the emulator break connection due to loss of power; an annoyance when running software and not a good thing to happen when programming the flash. 

    Regards,

    Nancy

  • 0 in reply to Nancy Jean Burkholder
    Guru 192875 points

    Nancy Jean Burkholder said:
    Thank you for your explanation of depletion. I tried depletion with UniFlash without success. I will proceed with replacing the processor.

    Sure!

    Nancy Jean Burkholder said:
    I suspect that these signals are susceptible to noise that could result in both FETs in a leg turning on, thus shorting the power supply.

    Be very careful, try using emi filters and increasing the deadbands for experimentation.

    Regards,

    Gautam

  • 0 in reply to Gautam Iyer
    Prodigy 50 points

    Gautam Iyer said:

    Be very careful, try using emi filters and increasing the deadbands for experimentation.

    I am using a reduced supply voltage and current so that worst case won't destroy anything; thus the power supply drops out occasionally. I am having the hardware modified to control the unitialized state of the PWM signals with pull-ups.

    Regards,

    Nancy