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ADS1293EVM: Measure 1 lead ECG without RLD?

lai zhengwei
Prodigy 30 points

Part Number: ADS1293EVM
Other Parts Discussed in Thread: ADS1293

Hello

I have some problem on ADS1293EVM.

My problem is could I measure 1 lead ecg without RLD?

It is mean that just need two electrodes to measure 1 lead ecg.

Like this image

I had tried that three electrodes to measure 1 lead ecg on both hand and one RLD.

It is work for me.

But when remove RLD it doesn't work.

I had search this issue many times.

But could not see some good solution for my problem.

Does it work when remove RLD in ADS1293?

If it work, It need some unique setting or connecting?

Thank You in Advance.

and Thank everyone who read text because my bad English writing skill..

Zhengwei

  • 0
    TI__Guru 58922 points
    Hello Zhengwei,

    Thank you for your post and welcome to the E2E forums!

    By RLF do you mean RLD - right leg drive? To confirm, more information on the RLD can be seen on page 23 of the datasheet.

    Page 48, figure 44 of the datasheet shows the RLD_CN: Right-Leg Drive Control register. You will need to power down the RLD amplifier which means that bit[3] of the RLD_CN register should be 1.

    Please let me know once you have tried this.
  • 0 in reply to Alexander Smith
    Prodigy 30 points

    Hello Alexander

    Thanks for your help!!

    I have tried to set bit[3] of RLD_CN register to 1.

    It doesn't work.

    When set it to 1, CMOR and CHxERR are turn to red sign.



    And signal couldn't see R peak of ECG clearly.

    Just read some messy signal like this


    Maybe it need more another setting or I need filter ecg signal that without RLD.

    I will keep test, make errors sign turn to green!!

    Thanks you a lot Alexander.

  • 0 in reply to lai zhengwei
    TI__Guru 58922 points
    Hello Zhengwei,

    You are most welcome!

    When you say that it does not work, do you mean that you are unable to set the register - or do you mean that the result of setting the register did not fix the initial problem and resulted in the red lights turning on?

    What are your digital filter settings like?

    Since you are not using the RLD circuit the ground is essentially floating, I believe this is why you are seeing so much noise. The two ways to fix this are to either use the RLD, or to use AC coupling capacitors (a capacitor in series to block the DC noise) on the input lines. Since you are using the EVM, removing RIN1 - RIN6 and replacing these 0Ohm resistors with an AC coupling capacitor may help fix the problem.

    Hope this helps!