ADS1291 general questions

HECTOR

Other Parts Discussed in Thread: ADS1291

Hello again ;

I need to finish my design but I need some technical supports as possible as you can and thank you in advanced.

Our design depends on ADS1291 to detect ECG signals and classify them . We would use only 2 leads there is no RLD lead . But I still need support with some issues.

1. I would use DC leadoff detection but I am using only two leads electrodes , so I cant block DC , what do you suggest a solution ?

2. I Have to measure the impedence of the body (resistive) the imperence between the two electrodes I could not find anything about this in the datasheet; please could you explain how to acheive that.

3. I have to detect PACEMAKER activities; hardware detection would be better but also could you suggest an example circuit to be added to ADS1291 ; know that i am using unipolar power supply (0-3.3v).If not hardware any example for software detection ?

4.Does anyone have an opensource ECG classification algorithm?

Thank you inadvanced

Hector

over 11 years ago

0 japex92 over 11 years ago

Prodigy 70 points

Hello Hector,

Please post your code so I can provide some advices.

rgds

0 HECTOR over 11 years ago in reply to japex92

Intellectual 865 points

Thank you Jairo ;

We still in the hardware design of the prototype ; we will start our tests and software development by the next week monday ; my problem still in understanding the issues I mentioned above.

0 HECTOR over 11 years ago in reply to HECTOR

Intellectual 865 points

Anyone please?

0 HECTOR over 11 years ago in reply to HECTOR

Intellectual 865 points

Please experts check my shematic especially for the RLD part ; since I am using one lead ECG .

Also I have set two poles low pass filter ; of cutt off frequency about 33kHz ;

Thank you

0 HECTOR over 11 years ago in reply to HECTOR

Intellectual 865 points

Also please check my PACE detector circuit.

I still could not find solution of the common mode voltage ( unipolar supply 0-3V) ; so please could you comment on the shematic.

Thank you

0 HECTOR over 11 years ago in reply to HECTOR

Intellectual 865 points

Anyone ?

0 HECTOR over 11 years ago in reply to HECTOR

Intellectual 865 points

The ADS1291 worked fine but I noticed all the readings is offsets by a DC volt about + 0.001volts, but I think it is ok , so you suggest a solution according to my shematic?

But the Pace detector citrcuit did not worked ... I am still trying to built another opamp circuit to test but if you have an example or please check my circuit that seems should work ..

Thank you in advanced

Hector

0 japex92 over 11 years ago in reply to HECTOR

Prodigy 70 points

Hello Hector,

This device has an offset error of 100uV. You can optimize the noise performance by adjusting the data rate and PGA setting. As the averaging is increased by reducing the data rate, the noise drops correspondingly. Increasing the programmable gain amplifier (PGA) value reduces the input-referred noise, which is particularly useful when measuring low-level biopotential signals. To start use a rate of 125 SPS and 2 for the PGA, then vary the gains and check the results.

Post the code we can go deeper...

Regards,

0 HECTOR over 11 years ago in reply to japex92

Intellectual 865 points

The code is on ARM cortex M4 there is no problem with the code it is working great; thank you Jairo for explanation;

what about of my pace maker detection circuit ; I am digital man .. poor analog. but it should work but it does not ; any advice?

Regards

Hector

0 HECTOR over 11 years ago in reply to HECTOR

Intellectual 865 points

Could it be the Common Mode voltage issue here ?

Analog guys ?

0 HECTOR over 11 years ago in reply to HECTOR

Intellectual 865 points

New Issue ;

I am trying to read the ECG again and again ; as I told the reading are ok ; but there always an offset voltage added to the signal and this offset voltage not fix to subtract it each time ; some times it about 0.01V somtimes it goes to negative , Do you suggest a solution ?

Should a pull up resistors to AVDD to the inputs helps to make this offset fix ?

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ADS1291 general questions