• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 46 subscribers
  • Views 644 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

ADS1278 EVM-PDK MCBSP Problem

Jonatan Vanegas
Prodigy 150 points
Other Parts Discussed in Thread: ADS1278

Hi,

I am interfacing ADS1278 EVM-PDK  with Piccolo f28335 via MCBSP. F28335 provide CLK and FSYNC signals internally. CLK aprox 1.97MHz and FSYN=CLK/256 in low power mode. Apparently, communication occurs successfully but when I get samples and graph them in CCS strangely in aprox 40th sample a oscillation occurs. is  like the conversion restarts. Could anyone tell me why happen this and how do it solve it?. 

These are some example of this.

1. Sine signal f=60Hz Fs=7709

2. DC Signal Fs=7709

Thanks.

  • 0
    TI__Guru 57326 points
    Hi Jonatan,

    Is this issue occurring periodically during your data capture?

    It seems like there is a timing violation that is causing you to miss data. Can you share a capture of the FYSNC interface signals? I can help you check it to ensure you are meeting all FSYNC timing requirements.

    Best Regards,
  • 0 in reply to Ryan Andrews
    Prodigy 150 points

    Hi Ryan

    Thanks for you reply 

    The oscillation happens periodically each samples block when I do any processing between them i.e. FFT, but when I sample uninterruptedly in a infinite loop the oscillation happens only at the first sample block. At first, I think it had to do the invalid samples that the ADS1278 datasheet mentions, but sometimes only sometimes this phenomenon doesn´t happens. Could be any electromagnetic compatibility problem?

    The signals that you ask are here:

    Fig 1. CLK(red) Vs DOUT(blue)

    Fig 2. FSYNC (blue) Vs SCLK-CLCK(red)

    Fig3 y 4. FSYNC (blue) Vs DOUT (red)

    Regards,

    Jonatan.

  • 0 in reply to Jonatan Vanegas
    TI__Guru 57326 points
    Hi Jonatan,

    Sorry for my delay - I was out of the office on travel most of last week. Any updates on this?

    I did not see anything inherently wrong with the signal captures you provided.