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TMS320F28335: TMS320F28335: Cause of reset?

Naveen Devara
Prodigy 80 points

Part Number: TMS320F28335

Hi TI,

We are working on TMS320F28335 - 176 pin DSP. We finished assembling of board and done with power-ON checks. During Power-ON checks we observed POWER-ON Reset is not stable and it is switching at regular intervals. We have not flashed the code yet and unable to connect the target as well. Could you please help me to find out reason.

  • 0
    TI__Guru** 117441 points

    Hi Naveen,

    During Power-ON checks we observed POWER-ON Reset is not stable and it is switching at regular intervals.

    Do you mean XRSn pin ? If yes then please check the setting of BOOTMODE pins. If settings are selecting the FLASH boot and Flash is not programmed then you'll see the XRSn pin toggle. Change the BOOTPIN setting to some other value and see if that fixes the issue.

    Regards,

    Vivek Singh

  • 0 in reply to Vivek Singh
    TI__Guru* 95315 points
    What you are seeing is the Watchdog timing out and resetting the device. This is the expected behavior on an erased part and completely normal. WD overflow frequency could be calculated with the following formula:

    [Input clock / 512] / ( 1 x 256)

    Your i/p clock is probably 30 MHz. This gives a reset frequency of 4.3 ms, which is what you are seeing. The width of the reset pulse is 512 i/p clock cycles, which is about 17 uS. If you program some code in flash which disables the WD, you should not see these resets anymore. You could also try changing the boot-mode, as Vivek suggests. Modes like SCI disable the WD.