• State
  • Locked Locked
  • Replies 4 replies
  • Subscribers 99 subscribers
  • Views 381 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DSP TMS320C6745 RTC issue

PRAVIN RAUT
Prodigy 85 points
Other Parts Discussed in Thread: TMS320C6745

Dear All,


We have designed DSP board around TMS320C6745 processor. we have run the processor initially at 25MHZ using external crystal

and pump the frequency to 300 MHz using internal PLL. we have interfaced RTC PCF8563 to processor. the communication between

RTC and processor is through I2C Bus.

After testing around 150 such boards we observed that RTC is not functioning in some of the board and works well in some

boards. if we replace the RTC IC PCF8563 from working board to non working board, RTC not work on that board. but if we

change the processor from non working RTC board then RTC starts functioning.

we feel that the problem is with Processor chips. we have such 90 procesors in stock. please suggest the solution to resolve

this issue. I have attached Schematic and software routine of our design for your referance.

The exact part numbers of the processors is : TMS320C6745CPTPD4.
1881.dsp_320_ver12.0.pdf0677.RTC routine.zip

RTC routine.zip
  • 0
    TI__Expert 7225 points

    Hi Pravin,

    How many boards out of 150 are not working? 

    And how many instances the replacement of  processor on non working board makes the RTC work? All of them or a %? 

    Please let me know.

    Best Regards

    Feroz

  • 0
    TI__Expert 7470 points

    Hi Pravin,

    From the comments in your attached code, I see that you use a prescaled module clock of 1 MHz. Is that correct? According to the TRM, you should be setting this to between 6.7-13.3 MHz

    Please also see the forum post on the noise immunity circuits built into the I2C which require the above clock range here.

    If this does not fix the issue, can you rule out soldering/board issues by replacing a known working device on a non-working board?

    Regards,

    Sunil Kamath

  • 0 in reply to Sunil Kamath
    Prodigy 85 points

    Thanks for your suggestion. we have checked the I2C clock prescaler and did the necessary changes. we have set the Prescaled module clock frequency to 8.3MHz and I2C serial clock frequency to 166KHz. we have download this updated program on our DSP boards and it is observed that Still RTC not working.

    You have suggested to check noise immunity circuits for I2C. The link above, which you have provided is not available. The screenshot is attached for your reference.

    Please suggest where I shall get the documents / information on noise immunity circuits for I2C. so that I can check the RTC by implementing this noise immunity circuits.   


    Thanks & regards,
    Pravin.

  • 0 in reply to PRAVIN RAUT
    TI__Expert 7225 points

    Hi Sunil,

    I have shared the internal forum post on noise immunity related discussion.

    Apparently after replacing with working processor the non-working board starts working. Not clear if this is always the case... Pravin?

    best Regards

    Feroz