Pressure.cpp

00001 #include "Pressure.h"
00002 #include "mbed.h"
00003 
00004 Pressure::Pressure()
00005 {
00006     _pressure = 0.0;
00007 
00008     _compressed[0] = 0;
00009     _compressed[1] = 0;
00010     _compressed[2] = 0;
00011 }
00012 
00013 Pressure::Pressure(float a, unitsType units)
00014 {
00015     setPressure(a, units);
00016 }
00017     
00018 Pressure::Pressure(const char* compressed)
00019 {
00020     setPressure(compressed);
00021 }
00022 
00023 Pressure::Pressure(const char msb, const char csb, const char lsb)
00024 {
00025     setPressure(msb, csb, lsb);
00026 }
00027 
00028 void Pressure::setPressure()
00029 {
00030     setPressure(_compressed[0], _compressed[1], _compressed[2]);
00031 }
00032 
00033 void Pressure::setPressure(float a, unitsType units)
00034 {
00035     // TODO:
00036 }
00037     
00038 void Pressure::setPressure(const char* compressed)
00039 {
00040     setPressure(compressed[0], compressed[1], compressed[2]);
00041 }
00042 
00043 void Pressure::setPressure(const char msb, const char csb, const char lsb)
00044 {
00045     long pressure_whole = (long)msb<<16 | (long)csb<<8 | (long)lsb;
00046     pressure_whole >>= 6; // Pressure is an 18 bit number with 2 bits of decimal. Get rid of decimal portion.
00047 
00048     float pressure_decimal = (float)((lsb&0x30)>>4)/4.0; // Turn it into fraction
00049 
00050     _pressure = (float)pressure_whole + pressure_decimal;
00051 }
00052 
00053 float Pressure::pressure(unitsType units)
00054 {
00055     // http://www.asknumbers.com/
00056     switch (units)
00057     {
00058         case PSI:
00059             return _pressure * 0.000145037738;    
00060         case INHG:
00061             return _pressure * 0.00029529983071;
00062         case MMHG:
00063             return _pressure * 0.007500615613;
00064     }
00065     
00066     return _pressure;
00067 }
00068 
00069 const char* Pressure::print(unitsType units)
00070 {
00071     sprintf(_printBuffer, "%.0f", pressure(units));
00072     return _printBuffer;
00073 }