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Original question:

ADS1292R: Single Shot Mode

ADS1292R: ADS1292R: trouble of Single Shot Mode

user1915296
Prodigy 110 points
Part Number: ADS1292R

We use the single shot mode ,we can get a 500us pulse on DRDY with the  DR[2:0]  setted to  110 . we get a 500us pulse on DRDY with the  DR[2:0]  setted to 011. So I think the chip enter the single shot mode.  We send a RDATA command after the DRDY change from High to lowm, but can't read  the correct data ( the test square ).  How can we get the corrrct data after the DRDY singal change to LOW?

  • 0
    TI__Guru 66386 points

    Hello,

    Welcome to our forum and thank you for your post

    You can confirm that you have entered Single-Shot Mode by reading the value of the CONFIG1 (01h) register. The default mode is Continuous Conversion Mode, so you will need to do the following:

    1. Stop the RDATAC Mode by sending SDATAC (0x11)
    2. Write to the CONFIG1 register (0x41 0x00 0x83)
    3. Read the CONFIG1 register to confirm (0x21 0x00)

    If you do not read any data, /DRDY will stay low until a few tCLK periods before the next falling edge. If you read the data, /DRDY returns high with the first SCLK falling edge.

    Best regards,

  • 0 in reply to Ryan Andrews
    Prodigy 110 points

    Hi,

       Thanks for your suggestion. I   confirmed that  the   CONFIG1 register  is  correct.

        We follow these steps to test the chip ,but cann't  get the data.

       A:Start the chip A (continuous mode ,250sps)

       B:Start the chip  B(single shot mode ,send the 'start' comand) after  the data reading of  chip A   ( the data is ok)  

       C: The DRDY of chipi B change to HIGH, Waiting the ...

        D: After 500us ,the DRDY of chip B change to LOW 

       E: Set  CS pin  and send the 'Rdata' command  

       F: Receive  the data, but all the data is 0

       G: The DRDY keep low until the step B coming

      

       

                 

        

       

     

  • 0 in reply to user1915296
    TI__Guru 66386 points

    Hello,

    Single-shot mode requires that you toggle the START pin or send the START command for EVERY conversion. The ADC will only complete 1 conversion at a time. Please read Section 8.5.1.12 of the data sheet.

    Also, I did not realize you were trying to use two ADS1292R devices. This sounds like a very unusual configuration (one device in continuous mode, the second device in single-shot mode). If the goal is to operate the second device slower than the first device, it is possible to do this while leaving both devices in continuous mode. The second device could be set to use a slower data rate. If the two devices share the same master clock, you could do something like:

    1. Device A: 1 kSPS
    2. Device B: 250 SPS

    Data from Device A will update every 1 ms while data from Device B will update every 4 ms. It is ok to read all data from both devices every 1 ms, just know that the data from Device B will be repeated three times. The data can be read using a Daisy-Chain or Cascaded Configuration. 

    Best regards,