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Trouble boot strapping when doing a warm restart via watchdog

Tim Groth
Prodigy 245 points
Other Parts Discussed in Thread: TMS320F28235

I'm trying to boot strap through the serial port SCI A.  If I set the GPIO levels for boot strap correctly and power down and power back up it works successfully. If I set the GPIO levels for boot strap correctly turn on the watch dog timer and purposively do not service it, after the reset it does not boot strap.   Perhaps some register needs to be reset and isn't getting reset?  Any ideas?

  • 0
    TI__Mastermind 19810 points

    Hi Tim,

    which device is this? WatchDOG should reset everything and bootROM should be able to re-initalize everything as is needed by it. I suspect that bootROM is detecting a different boot mode other than waht you expect it to be, coming out of the WDOG reset.

    can you scope out the boot mode pin levels and XRSn pin level across the reset and see if they are being set at the proper levels when bootROM begins to execute after WDOG reset? Maybe bootROM is detecting wrong boot mode? Also check the datasheet for reset hold times and boot mode pin hold times.

     

    Best Regards

    Santosh

     

  • 0 in reply to Santosh Athuru
    Prodigy 245 points

    This device is TMS320F28235.  With the watchdog reset I can see the reset active low for 15 uSec.  The boot mode levels had looked to be ok, but its possible that since they were outputs before the reset and also set to a low output even though the reset turns them back into inputs, with the external pullup resistors at 10K its very possible that there is enough capacitance on the board to prevent them from going to a good high right after reset.  I have changed my code to change them to inputs stall for a second then activate the watchdog reset.  This seems to have solved the issue although much more testing will be needed to make sure.  Thanks for helping me think it through.