'######################## DHT-22 Humidity & Temperature Sensor ####################

$regfile = "m8def.dat"
$crystal = 8000000
$baud = 9600
$hwstack = 64
$swstack = 64
$framesize = 64
Config Lcdpin = Pin , Db4 = Portd.4 , Db5 = Portd.5 , Db6 = Portd.6 , Db7 = Portd.7 , E = Portd.2 , Rs = Portd.3
Config Lcd = 16 * 2
Cursor Off
Cls

'#####################################

Config Pinc.2 = Input
Config Timer0 = Timer , Prescale = 8

'#####################################

'this has to be changed according to your frequency settings in $crystal
Const Min_time = 70
Dim Count As Byte
dim timec as byte
dim x as byte
dim chksum as byte
Dim Humidity1 As Word
Dim Temperature1 As word
Dim Humidity2 As Word
Dim Temperature2 As word
dim tneg as byte              'indicate if temperature<0
Dim Humsens_chksum As Byte
Dim Humiditys As String * 16
Dim Temperatures As String * 16

Do
  gosub Read_sensor1 'takes 3 seconds
  locate 1,1
  lcd Format(humiditys , "0.0")
  locate 2,1
  lcd Format(temperatures , "0.0")

  gosub Read_sensor2 'takes 3 seconds
  locate 1,8
  lcd Format(humiditys , "0.0")
  locate 2,8
  lcd Format(temperatures , "0.0")
Loop

End

Read_sensor1:

  Humidity1 = 0
  Temperature1 = 0
  Humsens_chksum = 0
  Wait 3
  Count = 1
  Config Pinc.2 = Output : Portc.2 = 0                    ' request data
  Waitms 20                                               ' wait 20 ms
  Config Pinc.2 = Input                                   ' wait for data, receive data

  While Count < 43                                        ' collect 42 timings / signals
    Bitwait Pinc.2 , Set                                  ' signal goes high > start timer
    Start Timer0
    Bitwait Pinc.2 , Reset                                ' signal goes low  > stop timer
    Stop Timer0
    timec=tcnt0
    Tcnt0 = 0
    Select Case Count
      Case 3 To 18
        X = 18 - Count
        If timec > Min_time Then Toggle Humidity1.x

      Case 19 To 34
        X = 34 - Count
        If timec > Min_time Then Toggle Temperature1.x

      Case 34 To 42
        X = 42 - Count
        If timec > Min_time Then Toggle Humsens_chksum.x
        'locate 1,1
        'lcd bin(humidityw);" "; bin(Temperaturew)

    End Select
    Incr Count
  Wend

'#############################################################
' Calculate Checksum and compare with trasnmitted value
'#############################################################

  Chksum = Low(humidity1) + High(humidity1)
  Chksum = Chksum + Low(temperature1)
  Chksum = Chksum + High(temperature1)
  If chksum=Humsens_chksum Then
    temperatures=""
    if temperature1.15=1 then
      temperature1.15=0
      temperatures="-"
   endif

   Humiditys = Str(humidity1)
   Temperatures = Temperatures+ Str(temperature1)
  end if

return

Read_sensor2:

  Humidity2 = 0
  Temperature2 = 0
  Humsens_chksum = 0
  Wait 3
  Count = 1
  ' Pin an Hardware hier anpassen!
  Config Pinc.3 = Output : Portc.3 = 0                    ' request data
  Waitms 20                                               ' wait 20 ms
  Config Pinc.3 = Input                                   ' wait for data, receive data

  While Count < 43                                        ' collect 42 timings / signals
    Bitwait Pinc.3 , Set                                  ' signal goes high > start timer
    Start Timer0
    Bitwait Pinc.3 , Reset                                ' signal goes low  > stop timer
    Stop Timer0
    timec=tcnt0
    Tcnt0 = 0
    Select Case Count
      Case 3 To 18
        X = 18 - Count
        If timec > Min_time Then Toggle Humidity2.x

      Case 19 To 34
        X = 34 - Count
        If timec > Min_time Then Toggle Temperature2.x

      Case 34 To 42
        X = 42 - Count
        If timec > Min_time Then Toggle Humsens_chksum.x
        'locate 1,1
        'lcd bin(humidityw);" "; bin(Temperaturew)

    End Select
    Incr Count
  Wend

'#############################################################
' Calculate Checksum and compare with trasnmitted value
'#############################################################

  Chksum = Low(humidity2) + High(humidity2)
  Chksum = Chksum + Low(temperature2)
  Chksum = Chksum + High(temperature2)
  If chksum=Humsens_chksum Then
    temperatures=""
    if temperature2.15=1 then
      temperature2.15=0
      temperatures="-"
   endif

   Humiditys = Str(humidity2)
   Temperatures = Temperatures+ Str(temperature2)
  end if

return