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ADS1299: DAISY CHAIN configuration issue in WREG data and wrong data in ADS1299-2

nivetha arun
Prodigy 150 points
Other Parts Discussed in Thread: ADS1299

Hi,

Interfacing 2 ads1299 ICs. Both are working fine independently.

I need to use daisy chain. But ads1299-1 I'm using for EEG and here srb1 wanted to enabled, unipolar. ADS1299-2 is for EMG, it is acting as an bipolar. so, srb1 should not be enabled.here, How to write the different MISC1 register data for both ICs in daisy chain configuration in a right manner? 

In hardware configuration, I shorted that START pin of both ICs and CLK pin of both ICs, daisy_in1 and dout2 is shorted. ads1299-1 clksel=1, sharing internal clock for both ICs. here i tried reading data from both ICs, 54 bytes(27 from ADS-1 and 27 for ADS-2),for ads1299-1 I got the expected data. In the second IC all data are 0s. why this happened?

Thank you in Advance!

  • 0
    TI__Guru 66446 points

    Hello Nivetha,

    Thank you for your post. 

    I believe I connected with your team offline and reviewed the schematic in February. Let me know if you prefer to discuss this further via email as well.

    If the internal oscillator of U1 is to be shared with U2, then you will need to configure the following:

    1. U1 CLKSEL pin should be pulled high to enable the internal oscillator. 
    2. Set U1 CLK_EN bit (CONFIG1[5]) to 1b to set the CLK pin as an output
    3. U2 CLKSEL pin should be pulled low to disable the internal oscillator; CLK pin becomes an input automatically.

    You can configure the register settings for each device independently since you have separate /CS signals in your schematic.

    Regards,

    Ryan

  • 0 in reply to Ryan Andrews
    Prodigy 150 points

    Hello Ryan, Thank you for your response.

    Sorry for the delay in reply. As per your recommendation, we followed the same configuration. For further issues, will connect to you back.