• State TI Thinks Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 1 answer
  • Subscribers 46 subscribers
  • Views 235 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ADS1291: Signal Interference Issue in 8-Channel ECG Data Acquisition: Analysis of Channel Dependencies and Anomalous Behavior using 8:1 demux (TMUX 1108) with ESP32 controller

Lalit Kushwaha
Prodigy 10 points
Part Number: ADS1291
Other Parts Discussed in Thread: ADS1292, TMUX1108

We are reading 8-channel ECG data using an 8:1 demux (TMUX 1108) to obtain one output. Afterward, we are converting this data using the ADS1291 with the assistance of an ESP32.

Problem: When we provide input to all 8 channels, we are able to receive proper data from all 8 channels. However, an issue arises when we remove the data input from one channel; in this case, three other channels are affected.

For example: If we remove the input from the first channel (which is floating), the 2nd, 3rd, and 4th channels stop working, while all the other channels continue to function properly.

The peculiar aspect is that the first channel provides accurate data.

Please provide your suggestions regarding the above situation. Is this scenario feasible?

  • 0
    TI__Mastermind 19815 points

    Hi,

    we will get back to you around or before 8/11

  • 0 in reply to ChienChun Yang
    TI__Mastermind 19815 points

    Hi,

    What are the signal source did you use to inject the channel?

    Could you first try to see if you can 

    1. read the Chip REV_ID[1:0]: Revision identification 

    2. 8.3.2.2 Test Signals (TestP and TestN) 

    "INT_TEST: Test signal selection
    and 

    " TEST_FREQ: Test signal frequency"

    to read the internal test signal.

  • 0 in reply to ChienChun Yang
    Prodigy 10 points

    Hi, Thank you for providing the answer. As you mentioned, we tested the test signal in ADS1292 and it was properly generated. After that, we are feeding the sine signal from the function generator.

    1) We tested the multiplexer(TMUX1108) by feeding a sine signal from the function generator into either one channel or all eight channels. We collected the data through the microcontroller using the analog pins. As a result of this test, we observed that the sine signal was properly generated in all eight channels as well as in a single channel.

    2) When we input a sine signal to the mux on a single channel and pass it through to the ADS1292, the signal we receive is proper. We then proceeded to test all eight channels by switching between them at a certain frequency, which also yielded proper signals.

    Problem

    However, when we removed the input signal from one channel (for instance, channel 1) by grounding or leaving it floating, we noticed that this change had an impact on the signals of the other channels."

  • 0 in reply to Lalit Kushwaha
    TI__Mastermind 19815 points

    Hi,

    It could be some grounding or common mode voltage issues between the function generator and your PCBA or PCBA's peripheral circuits.

    Could you try with an ECG simulator?

    i.e. ECG simulator to generate ECG signals to one channel or more than one channel and to all channels.

    thanks

  • 0 in reply to ChienChun Yang
    TI__Mastermind 19815 points

    Closing this ticket as I haven't heard update.

    Thanks.

  • 0
    Prodigy 10 points

    I also used the ECG simulator but data is not good