Arduino reads voltage from voltage divider with standard 10k resistor and NTC. Breathing causes NTC to change resistance which leads to voltage changes on divider. ATmega328 in Arduino reads voltage with ADC and passes data to LabView function. Function calculates average value and DFT to determine frequency.
First step is to acquire signal from voltage divider.
Next we determine acquired signal frequency and test it against threshold value. Every value is converted to string and logged in data.txt file
Button Read and Write in front control panel control this case structures