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TMS320F28335: Reset periodically after power on

Jim Chen (SEM)
Intellectual 2630 points

Part Number: TMS320F28335
Other Parts Discussed in Thread: TPS3809

Hi experts,

My customer is testing a board based on F28335 and find that XRS is driven low periodically.

The testing waveforms are as below.

VDDIO(blue) and VDD(yellow):

VDDIO(blue) and XRS(yellow)

XRS:

Since the oscilloscope used has a bandwidth of only 150M, the measured clock waveform is distorted, but the frequency is 30MHz.

clk of XCLKIN pin (yellow):

And customer provided some schematic.

Could you pls give some advice what causes F28335 reset periodically？

BR

Jim

  • 0
    TI__Guru** 117281 points

    Jim,

    Does customer have application code programmed in flash ? If not, have they checked that they have proper bootmode set on board ?

    Also is this new design or existing design where they are seeing the failure now ? 

    If new design, I am curious to know why are they using F28335 and not some latest device related from C2000 team.

    Regards,

    Vivek Singh

  • 0 in reply to Vivek Singh
    TI__Intellectual 2630 points

    Hi Vivek,

    Thanks for reply.

    This is quite new board and have not been programmed.

    It's a old schematic design but new board. I will check the bootmode pin in board.

    I will also recommend them to use latest device.

    BR

    Jim

  • 0 in reply to Vivek Singh
    TI__Intellectual 2630 points

    Hi Vivek,

    I have tested the bootmode pin which all stay high.

    After removing the reset IC TPS3809 and pulling up XRS to VDDIO by 3.3kohm directly, no more reset signal but also can't connect MCU by JTAG.

    Are there other issuses to try?

    BR

    Jim

  • 0 in reply to Jim Chen (SEM)
    TI__Guru** 117281 points

    Jim,

    I don't know if IC TPS3809 was issue. Generally if you are not able to connect to JTAG then it's either JTAG pin connectivity issue or power supply issue. 

    Also if all the bootmode pins are high then it means Flash BOOT and if flash is not programmed then it'll be 0xFFFF_FFFF which is ITRAP instruction and as per the below section in TRM, that will fire a WD reset which will toggle XRSn pin. 

    Regards,

    Vivek Singh