public float GetPressure(Accurateness accuracy, long rawTemp)
{
var waitTime = StartPressureMeasurement(accuracy);
Thread.Sleep(waitTime);
return FinishPressureMeasurement(accuracy, rawTemp);
}
private TimeSpan StartPressureMeasurement(Accurateness accuracy)
{
var oss = (int)accuracy;
//Reading raw pressure-data
WriteByte(0xF4, (byte)(0x34 + (oss << 6)));
if (accuracy == Accurateness.UltraLowPower)
return new TimeSpan(0, 0, 0, 0, 5);
else if (accuracy == Accurateness.Standard)
return new TimeSpan(0, 0, 0, 0, 8);
else if (accuracy == Accurateness.HighResolution)
return new TimeSpan(0, 0, 0, 0, 14);
else if (accuracy == Accurateness.UltraHighResolution)
return new TimeSpan(0, 0, 0, 0, 26);
else
throw new I2CException("Invalid accurateness");
}
public IAsyncTask<float> AsyncGetPressure(Accurateness accuracy, long rawTemp, AsyncCallback callback)
{
return DoWaitingTask(
(int)StartPressureMeasurement(accuracy).TotalMilliseconds,
() => FinishPressureMeasurement(accuracy, rawTemp));
}
private float FinishPressureMeasurement(Accurateness accuracy, long rawTemp)
{
var oss = (int)accuracy;
byte xlsb = 0;
long up;
if (accuracy == Accurateness.UltraHighResolution)
xlsb = ReadByte(0xF8);
up = ((ReadByte(0xF6) << 16) + (ReadByte(0xF7) << 8) + xlsb) >> (8 - oss);
long b6 = rawTemp - 4000;
long x1 = (B2 * (b6 * b6 / (1 << 12))) / (1 << 11);
long x2 = AC2 * b6 / (1 << 11);
long x3 = x1 + x2;
long b3 = (((AC1 * 4 + x3) << oss) + 2) / 4;
x1 = AC3 * b6 / (1 << 13);
x2 = (B1 * (b6 * b6 / (1 << 12))) / (1 << 16);
x3 = ((x1 + x2) + 2) / (1 << 2);
ulong b4 = AC4 * (ulong)(x3 + (1 << 15)) / (1 << 15);
ulong b7 = (ulong)(up - b3) * (ulong)(50000 >> oss);
long p;
if (b7 < 0x80000000)
p = (long)((b7 * 2) / b4);
else
p = (long)((b7 / b4) * 2);
x1 = (p / (1 << 8)) * (p / (1 << 8));
x1 = (x1 * 3038) / (1 << 16);
x2 = (-7357 * p) / (1 << 16);
p = p + (x1 + x2 + 3791) / (1 << 4);
return p / 100f;
}
