• State TI Thinks Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 1 answer
  • Subscribers 46 subscribers
  • Views 2195 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.

ADS1298: ADS1298 SPI not Reading

Daniel Paley67
Prodigy 50 points
Part Number: ADS1298

Hi All,

I've tried to replicate the Eval Kit as closely as possible.  I'm able to get that working (and watch the spi channels to confirm), but on my board, I cannot get the SPI channel to do anything.  I've looked at all the basics and seems that I'm using the part correctly (suspect a HW issue).  I can send the correct SPI (MOSI) commands to read the ID register, but MISO doesn't move.  What is the minimum needed to get SPI working?

I've got CLKSEL, RESET, PWDN tied high.  Spi is connected to a 3.3v system (nRF52).  I can include the schematic if necessary - but not sure what to look at next.

Could use a pointer or two.

thanks

--Daniel

  • 0
    TI__Guru 51351 points
    Hello Daniel,

    Thanks for your post and welcome to the forum!

    Sorry to hear that you're having issues communicating with the device.

    A couple of things to get us started:
    1) Does the ID register read back correctly?
    2) Are you following the correct start-up sequence in section 10.1.2 and 11.1? After the power-on reset is complete, /DRDY should begin pulsing at the default data rate (assuming the START pin is pulled up). The /RESET pulse after tPOR is essential for bringing up the digital core in the correct state.
    3) Before trying to read the registers, are you sending the SDATAC command?
    4) Can you provide a schematic?
    5) What is the frequency and how many SCLK pulses are you sending to clock data out?
  • 0 in reply to Alexander Smith
    Prodigy 50 points

    H Alex.

    1). no - no reads.  Dout does not toggle

    2). I'll check the startup sequence again - I'll check these signals tonight.

    3). not sending SDATAC command.  Is this required prior to sending a rreg?

    4).  pdf of schematic enclosed.

    5).  Frequency of SPI is currently 500khz  Confirmed that min's for pulse width are ok.

  • 0 in reply to Alexander Smith
    Prodigy 50 points
    Ok Alex. More information. I have (as you can see from the schematics) tied Reset high along with CLKSEL. I'm getting no transition on
    DRDY (steady high). Start is also tied low (per datasheet, was to use command reset and start), but cannot get anything in or out of the spi channel.
  • 0 in reply to Daniel Paley67
    Prodigy 50 points
    one last item: from 10.1.2 it state that VCAP1 should goto 1.1V. It's staying at 0V.
  • 0 in reply to Daniel Paley67
    Prodigy 50 points
    wait, had the wrong pin. VCAP1 is going to 1.1V alright. OK - put in a large delay between reset_op and sdatac_op. Now getting something out. Not sure if it is correct or not. But now there is life.
  • 0 in reply to Daniel Paley67
    TI__Guru 51351 points
    A step in the right direction Daniel!

    Let me know if you have further questions here, code to voltage conversion is probably next which is covered in this thread: e2e.ti.com/.../1363393

    If you have unrelated questions, please start a new thread!