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TMS320DM8168: RESET issue & SD Card booting issue

Suhan Shetty
Prodigy 165 points
Part Number: TMS320DM8168

Hi,

We are using TMS320DM8168CCYGA2 in our design. We have the micro SD interface to the processor for booting and file transfer functions. Our board is up and running, power supplies are up and sequenced properly. Now we are finding RESET issue in one of our board.We already proved the design in a prototype board with same design. Now we are in production stage and assembled one board initially. In this board we are observing RESET Out issue.

When we try to reset the processor, by giving low input to PORn with the help of manual reset switch, the processor is not going into reset mode, and we are observing high on the RSTOUTn pin.

We are unable to find out the cause for the issue, as we already have a board of same design with no issues.

Can anybody please help us with this.

How can we debug the issue and move forward.


  • 0
    TI__Guru**** 170625 points
    Hi Suhan,

    I special sequence must be followed to make a proper PORn signal. Check DM816x datasheet:

    8.2.2 Power-On Reset (POR pin)
    8.2.17 Reset Electrical Data and Timing - Figure 8-2. Power-Up Timing

    See also below wikis:

    processors.wiki.ti.com/.../Debug_Tips_for_DM81xx_Boot_Fail

    Regards,
    Pavel
  • 0 in reply to Pavel Botev
    Prodigy 165 points

    Hi,


    1. Check the power supplies are within spec or not.
    We have checked all the power,all the powers are within the range.

    2. Clocking:If you are using crystal, pls check if there is clock output from MXO pin
    We are using crystal clock DEV_MXO (27MHZ),this clock also coming properly.

    3. Check the power on sequence & reset are following spec.
    We have checked power sequence & PORn as per tms230m8168 datasheet.
    The device power supplies must be sequenced in the following order:
    1. 3.3 V
    2. 1-V AVS
    3. 1-V Constant
    4. 1.8 V
    5. 1.5 V
    6. 0.9 V
    Each supply must begin actively ramping between 0 ms and 50 ms after the previous supply in the sequence has reached 80% of its nominal value,
    All the power sequence is between within the spec.
    We have also checked processor last power(0.9V) w.r.t PORn timing,this timing is 555ms.(please confirm this PORn timing is ok or not?
    Power sequence waveform attached for your reference.


    4. Detect the boot pins are pullup/down as you expected or not.
    We have checked boot selection pullup/pulldown resistor,all values are expected value.

    Other Observation:
    *RSTOUTn is always high,it is not going low if we are giving the manual reset.
    *Our SD card is not booting,We have checked all the data, CLK & cmd lines.If I am giving RESET all the data,CLK & CMD lines are toggling(high/LOW).We have found same behaviour in working card also.My understanding is all these signal is toggling,so all the power & PORn is proper.
    But I am not able to understand why the RSTOUTn is always high & SD card is not booting?

    Regards,

    Suhan ShettyProcessor_Power_Sequence.7z

  • 0 in reply to Suhan Shetty
    TI__Guru**** 170625 points
    Suhan,

    You must make sure that PORn signal is asserted (going from high to low), then you must make sure that it is asserted (staying at low) - min value is 32C, see section 8.2.17 Reset Electrical Data and Timing

    Regards,
    Pavel