PSOC5 ECG UNSTABILITY

alsec_4003696 · ‎Mar 12, 2019

Hey everyone, I am kind of new here so if any mistake sorry about that .

Currently I am using PSoC5 LP - CY8C5888LTI-LP097. I am trying to get ECG signal by using ADC. The chain i have used in my schematic is shown below.

First of all i tried 3 LEAD measurement. I have connected probes on my wrists(which is not problem because i have tested with real ecg device it is working on 2 wrists and one on the left waist). I get really good data on the oscilloscope. One day after, I can't see any good data on the oscilloscope, looks a lot of noise. However, whenever i apply some pressure on the probe on my left wrist or move it to find best contact i can see the data but with some noise. I don't know why i have this problem. It is really weird that sometimes i had really pure data just like in the real ecg device, sometimes i don't. By the way, my left waist is connected to GND of the PSoC5 and i am triying to measure (differential) left-right or vice versa.

Lastly, i am using AD8232 PCB board only for connections jack and probes. I don't even power it up.

If anyone have idea about this issue I would be happy to hear answer. Thanks a lot!.

ADC config:

AnDu_1277466 · ‎Mar 15, 2019

I attached detail of an equivalent circuit developed by hardware. It was designed as a low consumption circuit, which also does not use CPU. What you are interested in is the integrator part, as it is designed. I observe that you make the voltage reference to GND in the integrator (RL), possibly you have the problem at this point. If you want to use only two electrodes you should derive the integrator to the RA and RL inputs, but the filtering of the noise is always better with three leads.

The ECG of surface of the heart can be around 500uV to 3 mV, and depends on the capacity of the cardiac muscle, the volume and if it is in perfect conditions. Depending on what you want to detect, you can design the band pass filter between 0.5 Hz to 45 Hz or up to 200 Hz.

Study and practice with these designs and you will find the solution to your problem, the input signals must have a reference voltage, and that is RL.

I hope you can solve your problem.

a greeting

Te adjunto detalle de un circuito equivalente desarrollado por hardware. Fué diseñado como circuito de bajo consumo, que además no utiliza CPU. Lo que te interesa es la parte del integrador, como está diseñado. Observo que haces la referencia de voltaje a GND en el integrador (RL), posiblemente tengas el problema en este punto. Si quieres utilizar solamente dos electrodos deberías derivar el integrador a las entradas RA y RL, pero el filtraje del ruido siempre es mejor con tres derivaciones.

El ECG de superficie del corazón puede estar alrededor de 500uV a 3 mV, y depende de la capacidad del musculo cardiaco, del volumen y de si está en perfectas condiciones. Según lo que desees detectar puedes diseñar el filtro pasabanda entre 0,5 Hz a 45 Hz o hasta 200 Hz.

Estudia y practica con estos diseños y encontraras la solución a tu problema, las señales de entrada deben tener un voltaje de referencia , y ese es RL.

Espero que puedas resolver tu problema.

Un saludo

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PSOC5 ECG UNSTABILITY

PSOC5 ECG UNSTABILITY

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