Breathalyzer running on the MBED 1768 Platform; EE4427 Group 3 Spring 2018
Dependencies: 4DGL-uLCD-SE mbed
Diff: convertToBAC.cpp
- Revision:
- 0:35f90b280233
diff -r 000000000000 -r 35f90b280233 convertToBAC.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/convertToBAC.cpp Mon Apr 23 22:18:27 2018 +0000 @@ -0,0 +1,11 @@ +//Written by Todd Clark +#include "convertToBAC.h" + +float getBAC(float input){ + float voltage = input * 3; //Conversion from input resistance to voltage. + float calibratedVoltage = voltage / 0.6; //Convert voltage to work with our 3 volt output signal. + float ppm = 1033.992 + (55.84479 - 1033.992)/(1 + pow((calibratedVoltage/4.540421), 8.423297)); //Calculate ppm from our voltage values based on specs for MQ-3 gas sensor. + float bac = (ppm * 0.21) / 100; //Calculate BAC from ppm. Formula taken from http://nootropicdesign.com/projectlab/2010/09/17/arduino-breathalyzer/ + float calibratedBac = bac - 0.12; //Calibrate sensor based on value at 0% alcohol. + return (calibratedBac < 0.0) ? 0 : calibratedBac; +} \ No newline at end of file