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ADS1292 oscilloscope test

Trung Tran
Prodigy 70 points
Other Parts Discussed in Thread: ADS1292




Hi everyone,

I tested the analog output of the ADS1292 (ECG input in channels IN1N and IN1P). I connected the 2 channels of Oscilloscope to the output pins. The probe of channel 1 connect to the pin PGA1N, the probe of channel 2 connect to the pin PGA1P and both the ground clip are connected to the ground. I use the Arduino Uno as my micro controller (Digital supply is 3.3V and Analog supply is connected to the Vin pin of the Arduino). Below are the images of the displayed result below. 
The result is not what I expected but I can't figure out what I did wrong. Did I incorrectly connect the probe to the right pin? Or could my ADS1292 be broken?  

The displayed output when connect to PGA1P and PGA1N. Channel 1 and 2 respectively.


The displayed input when connect to IN1P and IN1N. Channel 1 and 2 respectively. 

  • 0
    TI__Guru**** 180821 points

    Hi Trung,

    The input/output looks the same, so that's at least a start! What is the source of your input? I suspect something is not properly grounded. Also, your volts/division looks wrong - I suspect you have a 10:1 probe setup incorrectly in the o-scope settings, 50V/div is probably 5V/div in reality.

  • 0 in reply to Tom Hendrick
    Prodigy 70 points
    Hi Tom,

    My input is the ECG signal from the electrodes. I measure the voltage difference between right arm and left arm (Lead I). May I ask if connecting the probe to the pin PGA and the ground clip to the ground is correct for measuring the analog output? Also, I set the PGA Gain = 8 in the firmware but the Pk-Pk voltage in both the input and output are ~160V, I think this is too much and incorrect for an ECG signal. Is my ADS1292 malfunction?
  • 0 in reply to Trung Tran
    TI__Guru**** 180821 points
    Hi Trung,

    Can you try using a signal generator to input a signal to the ADS1292? Check the probe attenuation on your scope and make sure it matches the probe that you are using, I'm nearly positive that you do not have 160V on the input/output of the ADS1292. Please also make sure your micro controller board ground is connected to the ADS1292 ground (both AGND and DGND nodes).