private static byte LireOctet(DHT22SignalBus signalDHT, byte noOctet)
{
byte res = 0;
for (int i = noOctet * 8; i < (noOctet + 1) * 8; i++)
{
res <<= 1;
res += LireBit(signalDHT, i);
}
return(res);
}
private static DHT22Mesure ConvertirValeurs(DHT22SignalBus signalDHT)
{
uint humidMSB = LireOctet(signalDHT, 0);
uint humidLSB = LireOctet(signalDHT, 1);
uint TempMSB = LireOctet(signalDHT, 2);
uint TempLSB = LireOctet(signalDHT, 3);
uint chk = LireOctet(signalDHT, 4);
if (((humidMSB + humidLSB + TempLSB + TempMSB) & 0xff) != chk)
{
return(null);
}
else
{
return(new DHT22Mesure(humidMSB, humidLSB, TempMSB, TempLSB));
}
}
public static DHT22SignalBus LireSignal(GpioPin pin)
{
DHT22SignalBus res = new DHT22SignalBus();
GpioPinValue etatCourant;
GpioPinValue etatPrecedent;
//******** Commande *********
pin.Write(GpioPinValue.Low);
pin.SetDriveMode(GpioPinDriveMode.Output);
res._t1max = Stopwatch.GetTimestamp() + _l1max;
while (Stopwatch.GetTimestamp() < res._t1max)
{
}
pin.SetDriveMode(GpioPinDriveMode.Input);
//***** Attente retour ******
etatPrecedent = pin.Read();
res._t2max = Stopwatch.GetTimestamp() + _l2max;
do
{
etatCourant = pin.Read();
if ((etatCourant != etatPrecedent) && (etatCourant == GpioPinValue.High))
{
break;
}
if (Stopwatch.GetTimestamp() > res._t2max)
{
return(res);
}
} while (true);
//****** Acquisitions *******
res._t3max = Stopwatch.GetTimestamp() + _l3max;
do
{
etatCourant = pin.Read();
if ((etatPrecedent == GpioPinValue.High) && (etatCourant == GpioPinValue.Low))
{
res.tFe[res.iFe++] = Stopwatch.GetTimestamp();
}
etatPrecedent = etatCourant;
} while ((res.iFe < NB_MAX_FRONTS_DESCENDANTS) && (Stopwatch.GetTimestamp() < res._t3max));
return(res);
}
public DHT22Mesure Lire(int nbMaxEssais)
{
DHT22Mesure res = null;
if (_pin != null)
{
int i = 0;
while ((i < nbMaxEssais) && (res == null))
{
DHT22SignalBus SignalDHT22 = DHT22SignalBus.LireSignal(_pin);
if (SignalDHT22.iFe >= DHT22SignalBus.NB_MAX_FRONTS_DESCENDANTS)
{
res = ConvertirValeurs(SignalDHT22);
}
i++;
}
}
SurNouvelleMesure?.Invoke(this, res);
return(res);
}
private static byte LireBit(DHT22SignalBus signalDHT, int noBit)
{
return(((signalDHT.tFe[noBit + 1] - signalDHT.tFe[noBit]) > DHT22SignalBus.SEUIL_BIT) ? (byte)1 : (byte)0);
}
