Now a very popular topic for DiY – Covid19 diagnostic devices. One such device is a pulse oximeter, which measures blood oxygen saturation during the exacerbation of the disease.
You can use MAX30100 chips, or even better MAX30102, or ready-made modules on these chips to make homemade devices.
We also decided to make a pulse oximeter.
The module on the MAX30102 chip is inexpensively purchased on Aliexpress. In a few minutes they connected the modules and started programming.
We do not know about the level of trust of our dear colleagues to the components and modules purchased online, but in this case we realized that you need to carefully check not only the quality of soldering, but also the circuitry.
We have previously dealt with errors in the operation of one of the integrated sensors (chip) but did not investigate this incident to the end. The developers of the module of this pulse oximeter made a gross circuit error.
I will not tire readers with our search for the causes of disability. We recommend reading about this in the article MAX30100 / MAX30102
Resume: after correcting the error, the module started working.