Diff: Pressure.cpp

Revision:

0:beb43bc3d6d4

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Pressure.cpp	Tue Apr 01 21:35:23 2014 +0000
@@ -0,0 +1,73 @@
+#include "Pressure.h"
+#include "mbed.h"
+
+Pressure::Pressure()
+{
+    _pressure = 0.0;
+
+    _compressed[0] = 0;
+    _compressed[1] = 0;
+    _compressed[2] = 0;
+}
+
+Pressure::Pressure(float a, unitsType units)
+{
+    setPressure(a, units);
+}
+    
+Pressure::Pressure(const char* compressed)
+{
+    setPressure(compressed);
+}
+
+Pressure::Pressure(const char msb, const char csb, const char lsb)
+{
+    setPressure(msb, csb, lsb);
+}
+
+void Pressure::setPressure()
+{
+    setPressure(_compressed[0], _compressed[1], _compressed[2]);
+}
+
+void Pressure::setPressure(float a, unitsType units)
+{
+    // TODO:
+}
+    
+void Pressure::setPressure(const char* compressed)
+{
+    setPressure(compressed[0], compressed[1], compressed[2]);
+}
+
+void Pressure::setPressure(const char msb, const char csb, const char lsb)
+{
+    long pressure_whole = (long)msb<<16 | (long)csb<<8 | (long)lsb;
+    pressure_whole >>= 6; // Pressure is an 18 bit number with 2 bits of decimal. Get rid of decimal portion.
+
+    float pressure_decimal = (float)((lsb&0x30)>>4)/4.0; // Turn it into fraction
+
+    _pressure = (float)pressure_whole + pressure_decimal;
+}
+
+float Pressure::pressure(unitsType units)
+{
+    // http://www.asknumbers.com/
+    switch (units)
+    {
+        case PSI:
+            return _pressure * 0.000145037738;    
+        case INHG:
+            return _pressure * 0.00029529983071;
+        case MMHG:
+            return _pressure * 0.007500615613;
+    }
+    
+    return _pressure;
+}
+
+const char* Pressure::print(unitsType units)
+{
+    sprintf(_printBuffer, "%.0f", pressure(units));
+    return _printBuffer;
+}