Max30102 heart rate blood oxygen sensor measures heart rate problem 2

1nnocent

Max30102 heart rate blood oxygen sensor measures heart rate problem 2 [Copy link]

Last time, I posted a post about the inaccurate heart rate measurement of max30102. In the last question, the measured heart rate was between 100-500, the waveform was relatively large, and the heart rate could basically not be measured (the measured data was basically not within the normal heart rate range). I took a rough look at the algorithm file, and configured the sampling rate of the chip according to the algorithm, and set the final formula for calculating the heart rate according to the sampling rate and verified it. The measured heart rate range was between 40-150, which was closer to the normal heart rate range this time, but there was still a problem of unstable data, and the fluctuation was relatively large. The data collected from the red light and infrared light of the chip was passed into the algorithm function, and then the infrared data was processed first in the function, and the heart rate was obtained through a calculation formula; then the processed infrared data and the initially processed red light data were used again to obtain blood oxygen.

The blood oxygen value can always be measured correctly, and the algorithm of the blood oxygen value includes a part of the heart rate processing, but the result is that the heart rate has a problem, but the blood oxygen is not. In the process of processing the heart rate data, the formula is finally processed. This formula is converted into the number of heart rate per minute to obtain the data displayed in the microcontroller, so the problem should be in the final formula. According to this idea, the sampling rate and the final formula were changed, but the final effect still failed to measure the heart rate, which was only close to the normal range. This time it is probably determined that the problem is the final calculation formula and the sampling rate.

The following are the results of this measurement:

The last measurement result:

1nnocent

After comparing many versions of the code on the Internet, the chip configuration is varied, especially the sampling rate, but the heart rate calculation formula in the algorithm file is the same. I guess they dare not easily change the algorithm file, and can only change the register configuration.