Question about ADS1299 Daisy-Chain with STM32

laumunglaumung
edited July 2017 in Other Platforms
Hello everyone:
   I have made a 24ch-EEG sampling system using 3 ADS1299 and STM32 ARM. Now I meet some problem. 
   The system is configured in Daisy-Chain Mode. The 3 ADS1299 share the same CS, CLK, SCLK,DIN,START, PWDN and POWER pin. The DOUT of first ADS1299 is connected to the STM32, the DOUT of second ADS1299 is connected to the Daisy-In of first ADS1299, the third DOUT is connected to the second Daisy-In. The Daisiy-IN of the third ADS1299 is connected to the GND. The first DRDY is connected to the STM32 and the other two are not connected to any pin. The CONFIGURATION REGISTER 1 is 0X96. 
   But now I can write and read the registers correctly, but the data output is all "0xff". I don't know what is the reason. Could you please help me? Thank you very much.
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Comments

  • laumunglaumung
    Hi everyone, I have made some progress. I can read data from the first two ADS1299 through daisy-chain. But the data of the third is still 0xff. How many ADS1299s could be made up into one daisy-chain?   Thank you very much.
  • plutopluto mars

    Hi @laumung,
    I am also trying to integrate multiple ADS1299 using DaisyChain,
    It would be grate if you can describe, how did you resolve 0xff from all the ADS1299, and what casued the issue?
    Thanks & Regards,
    Pluto

  • wjcroftwjcroft Mount Shasta, CA

    I don't believe 'daisy chain mode' is being used for Cyton firmware. One reason for this is that avoiding daisy allows more flexibility in configuring the hardware settings for each individual chip.

    https://docs.openbci.com/Software/OpenBCISoftware/GUIWidgets/#hardware-settings

  • plutopluto mars

    Thanks for your input William. Great point, probably I will re think this again.

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