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ADS1299: Multiple ADS1299 in CASCADE Mode

Sumit Mourya
Expert 1800 points
Part Number: ADS1299

Tool/software:

Hi,

I'm planning to use three ADS1299 in Cascade Mode for my 24channel setup. I wanted to clear some doubts regarding the connections between the Three IC'S

  1. 1st ADS will operate with its internal clock and It will output its clock to the other two ADS. Is this correct?
  2.  Can I consider the DRDY pin of only the 1st ADS? If yes, the other two ADS DRDY PINS can be left floating ?
  3. SPICLK,MISO,MOSI will be common for all ADS. Each ADS will have its own CS Pin.

I have been using Daisy chain mode before But it is not very robust as I get 0x00 values sometimes in any one of the three ADS'S channels. 

Kindly help my Queries. Please add the steps If I'm missing anything.

  • 0
    TI__Guru 66466 points

    Hello Sumit,

    Thank you for your post.

    1. Yes, the primary ADS1299 device can use the internal oscillator and output the clock to the other two devices. Alternatively, you can use an external oscillator as an input to all 3 devices if you require lower jitter or frequency tolerance.
    2. If you expect to operate all channels at the same data rate, then yes, you may leave /DRDY floating in device 2 and 3. For debug purposes, it may be helpful to route each /DRDY signal to a test point such that device synchronization can be verified.
    3. Yes, all SPI signals will be common across devices with the exception of /CS. /RESET, START, /PWDN can be shared.

    Regards,

    Ryan