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c6748 brown out

Hi,

My c6748 based electronics will be used in an environment where power  from outside will switch off without warning. Internally I control incoming voltage and will get an interrupt to DSP. I've equipped the board with a large set of capacitors, but I need to save most of the stored energy for SSD- chip to do a controlled flush and shutdown to save file system.

So when power fail interrupt signal activates interrupt server routine, I need to senf "flush" through SATA to SSD and then minimize DSP's power consumption, could you please assist me what would be most effective way to do it?

risto 

  • Risto,

    This would be the perfect application of the NMI since what you want to do must interrupt any other activity and also has no requirement to return to the point of execution, although that point of execution can be saved if later it is important to know.

    This will work if you do not need the TI-RTOS (BIOS) running to handle you shut-down activities. If you do need TI-RTOS, then you may have to test it to confirm it will work. I cannot say for sure what might break in this case, but it may not be a condition that is well-known. You would want to ask for more information on the E2E TI-RTOS Forum.

    From the hardware point-of-view, you can use the NMI to interrupt whatever you are doing. You will want to stop any ongoing EDMA activity, if it could be long, and disable any peripheral events that might be enabled to the EDMA. When you have the device cleaned up in terms of activity, then you can start turning off any modules that are controllable through the PSC Power and Sleep Controller. This will allow you to get down to the lowest possible point level for the device before the supply rails are shut down. You can also consider shutting off some clock inputs or slowing them, but that will depend on what you are doing and what you need on / full speed.

    If you have not searched the forum for similar issues, this would be a good one to look for. It makes sense that others may have tried to do this, too. Even if on a different device, their experience could be helpful.

    Regards,
    RandyP

  • Thank you Randy,

    Yes, NMI ->PSC seems to be the right path; core seems to take some 800mW@1,3V according to spreadsheet, if I deactivate  LPSC 15, PD_DSP (PD1)  will it drop core power consumption - this would be the very last command ;-)

    Regards,

    Risto