Rom-ID Finder for 1-wire devices on a multidrop line

[Theo]

'''Rom ID Finder for Multidrop and hardware serial output with Atmega8
'''------------------------------------------------------------------------
'''
'''This program is based on the Search Algorythm described in MAXIM AN817.
'''The variable names are (as far as possible) identical to the application note.
'''The CRC8 algorythm is based on public sources found on the internet.
'''
'''The program searches and finds the Rom ID's of multiple 1-wire devices
'''connected to a so called Multidrop. A Multidrop is a line with 2 or more
'''1-wire devices connected in normal or parasite Power mode.
'''Parasite Power mode is not supported for now.
'''
'''
'''This program can be adapted to any of the supported microprocessor
'''by simply changing the #chip as follows: #chip 16f877a, 4
'''and by choosing the right connections for the Hardware UART and OW input pin.
'''
'''@Theo Loermans
'''@licence GPL
'''@version 1.0
'''@date    08.03.2016
'''********************************************************************************

  #chip mega8, 16

  ; ----- Define Hardware settings
  ; Required to LCD to Serial redirection
  #define LCD_IO 0
  #define USART_BAUD_RATE 9600
  Dir PORTD.1 Out
  Dir PORTD.0 In
  #define USART_BLOCKING

  ; #define debug                   ' if activate, the script produces additional output
  #define DQ PortB.0            ; input pin for 1-wire device(s), normal power mode with pullup 4K7
  Dim ROM_NO(9) as byte   ; 9 ROM_NO bytes to store ID Bytes + CRC; don't use ROM_NO(0)
  Dim ByteNum as byte

  'DS18X20 Settings
  #define SearchRom 240                         '0xF0 (240) 'Command for identifying Slave Rom codes,
  #define ReadPowerSup 180                  '0XB4 (180) 'Read Power Supply mode
    #define SkipRom 204                             '0xCC (204) 'Command for addressing all devices simultaneously

'Start main program
    HSerPrint "Multidrop ID-Search.":CRLF
  HSerPrint "No. Family + Rom Number = ID-Number        CRC    Status":CRLF

    MasterRST                                           ' reset and check presence of sensor(s)

  if command = 2 then
    HSerPrint "Check line, shorted?":CRLF
        End                                                 ' exit script, resolve problem
  end if

  if command = 1 then
        HSerPrint "No device(s) detected!":CRLF
    End                                                 ' exit script for now, future expand
    end if

' sequence for checking Power Supply Mode
    OWout SkipRom
    OWout ReadPowerSup                      ' read power Supply Mode
  OWinBit Command
    If not Command Then
        HSerPrint "Parasite power mode detected!":CRLF
    HSerPrint "Not supported now, program end.":CRLF
    End                                                 ' Parasite mode not supported now, stop program
    end If

''Init Variable
    TotDevF = 0
    LastDiscrepancy = 0
  LastFamilyDiscrepancy = 0
  LastDeviceFlag = 0
  Returnvalue = 0
  For Bytenum = 1 to 9
    ROM_NO(Bytenum)=0
  Next

' Start ID Search
    Search ' This is the first Search

Do
  If Returnvalue = 1 then
        #ifdef debug
      HSerPrint "Returnvalue = 1":CRLF
      HSerPrint "LastDeviceFlag = ":HSerPrint LastDeviceFlag:CRLF
    #Endif
    if TotDevF < 10 then HSerPrint " "
    HSerPrint TotDevF:HSerPrint "  "
    HSerprint "0x":HSerPrint HEX(ROM_NO(1)):HSerPrint "   "
    For Bytenum = 2 to 7
        HSerprint "0x":HSerPrint HEX(ROM_NO(Bytenum)):HSerPrint " "
    next
    HSerprint "  0x":HSerPrint HEX(ROM_NO(8)):HSerPrint "   "
    #ifdef debug
      HSerPrint "0x":HSerPrint HEX(CRC):HSerPrint "   "
    #Endif
    If CRC = ROM_NO(8) Then ' Calculated CRC identical to found CRC?'
        HSerPrint "OK :-)"
    Else
        HSerPrint "Error :-("
    end if
    CRLF
  Else
    HSerPrint "ID-Search finished." : CRLF:CRLF
    End             ' stop program
  end if
  Search ' second and further Search until Returnvalue = false
Loop

'-------------------------SUB------------------------------------

Sub Search          ' Start ID Search
  MasterRST
  If LastDeviceFlag = 1 Then
    Returnvalue = 0
    Goto Ready  'Search Finished
  end if

  id_bit_number = 0
  last_zero = 0
  Bytenum = 1
  BPiB = 0 ' Bit position in Byte (ROM_NO)

  OWout SearchRom

  Do While id_bit_number < 64 ; (0-63)
    OWInBit id_bit          'read 1 bit from device
    OWInBit cmp_id_bit  'read 1 bit (complement) from device

    if id_bit = 1 AND cmp_id_bit = 1 Then 'invalid value's
      HSerPrint "No answer from device(s)!": CRLF
      Returnvalue = 0
      Goto Ready
    end if

    If id_bit = 0 AND cmp_id_bit = 0 Then ' 2 or more devices have the same bit value in common
            #ifdef debug
          HSerPrint "0-0 Discrepancy ":CRLF
        #Endif

      If id_bit_number = LastDiscrepancy Then
        Search_Direction = 1
      else
        If id_bit_number > LastDiscrepancy Then
          Search_Direction = 0
        Else
            CalcBPiB
            Select Case BPiB
              Case 0
                Set Search_Direction = ROM_NO(Bytenum).0
              Case 1
                Set Search_Direction = ROM_NO(Bytenum).1
              Case 2
                Set Search_Direction = ROM_NO(Bytenum).2
              Case 3
                Set Search_Direction = ROM_NO(Bytenum).3
              Case 4
                Set Search_Direction = ROM_NO(Bytenum).4
              Case 5
                Set Search_Direction = ROM_NO(Bytenum).5
              Case 6
                Set Search_Direction = ROM_NO(Bytenum).6
              Case 7
                Set Search_Direction = ROM_NO(Bytenum).7
            End Select
              #ifdef debug
              HSerPrint "Bytenum= ":HSerPrint Bytenum:HSerPrint " BPiB= ":HSerPrint BPiB
              HSerPrint " Search dir= ":HSerPrint Search_direction:CRLF
                  #Endif
        end if
      end if

      If Search_Direction = 0 Then
        last_zero = id_bit_number
        If last_zero < 8 Then
          LastFamilyDiscrepancy = last_zero
        end if
      end if
    Else
      Search_Direction = id_bit
    End if
        CalcBPiB

    Select Case BPiB
        Case 0
           if Search_Direction = 1 then
             Set ROM_NO(Bytenum).0 On
           else
             Set ROM_NO(Bytenum).0 Off
           end if
        Case 1
           if Search_Direction = 1 then
             Set ROM_NO(Bytenum).1 On
           else
             Set ROM_NO(Bytenum).1 Off
           end if
        Case 2
           if Search_Direction = 1 then
             Set ROM_NO(Bytenum).2 On
           else
             Set ROM_NO(Bytenum).2 Off
           end if
        Case 3
           if Search_Direction = 1 then
             Set ROM_NO(Bytenum).3 On
           else
             Set ROM_NO(Bytenum).3 Off
           end if
        Case 4
           if Search_Direction = 1 then
             Set ROM_NO(Bytenum).4 On
           else
             Set ROM_NO(Bytenum).4 Off
           end if
        Case 5
           if Search_Direction = 1 then
             Set ROM_NO(Bytenum).5 On
           else
             Set ROM_NO(Bytenum).5 Off
           end if
        Case 6
           if Search_Direction = 1 then
             Set ROM_NO(Bytenum).6 On
           else
             Set ROM_NO(Bytenum).6 Off
           end if
        Case 7
           if Search_Direction = 1 then
             Set ROM_NO(Bytenum).7 On
           else
             Set ROM_NO(Bytenum).7 Off
           end if
    End Select

      #ifdef debug
            if id_bit_number < 10 then HSerPrint " "
            HSerPrint id_bit_number: HSerPrint ")"
            HSerPrint " id_bit=":HSerPrint id_bit
            HSerPrint "  cmp_id_bit=":HSerPrint cmp_id_bit
            HSerPrint "  Bytenum=":HSerPrint Bytenum
        HSerPrint "  BPiB=":HSerPrint BPiB
            HSerPrint "  ROM_NO(":HSerPrint Bytenum:HSerPrint ")=0x"
            HSerPrint Hex(ROM_NO(Bytenum))
            HSerPrint "  Search dir=":HSerPrint Search_Direction 'CRLF
            HSerPrint "  last_zero=":HSerPrint last_zero
          HSerPrint "  LastDiscrepancy=":HSerPrint LastDiscrepancy
            HSerPrint "  LastFamilyDiscrepancy=":HSerPrint LastFamilyDiscrepancy:CRLF
        #Endif

    OWoutBit Search_Direction ' send search_direction bit to device

    Bytenum = (id_bit_number/8) + 1     ' calculate Byte number (1-8) for ROM_NO bytes
    id_bit_number = id_bit_number + 1 ' increment ID bit number (0-63)
  Loop
  LastDiscrepancy = last_zero
  If LastDiscrepancy = 0 Then
    LastDeviceFlag = 1
  end if

    CRC = 0                               ' Calculate CRC8: DALLAS/MAXIM, reversed Polynomial
  For index = 1 to 7
    _DB=ROM_NO(index)
    Repeat 8
      FB = (_DB XOR crc) AND 1
      CRC = CRC/2
      _DB = _DB/2
      if FB = 1 then
        CRC = CRC XOR 140 ' 0x8C
      end if
    end Repeat
  next
    Returnvalue = 1

  Ready:
  if Returnvalue = 0 then
    LastDiscrepancy = 0
    LastFamilyDiscrepancy = 0
    LastDeviceFlag = 0
  end if
    TotDevF = TotDevF + 1 ' Increment Total Devices Found
end Sub

Sub CRLF                ' Carriage return, Line feed
  HSerSend 13
  HSerSend 10
End sub

Sub CalcBPiB            ' by using bytes for the variables there are no fractions if you divide
  Bytenum = (id_bit_number/8)+1                              ' calculate Byte number (1-8)
  BPiB = id_bit_number - ((id_bit_number/8)*8) ' calculate Bit position in Byte (0-7)
end Sub

Sub OWin (Command)
 IntOff                                                   ' Interrupt Disabled
 Repeat 8
  Rotate Command Right                      ' LSB first
  Dir DQ Out
  Set DQ Off                                        ' Start time slot
  wait 6 us
  Dir DQ In                                         ' Release bus for one wire Reception
  wait 9 us
  If DQ On  Then Set Command.7 1
  If DQ Off Then Set Command.7 0
  wait 55 us
 End Repeat
 IntOn                                                      ' Interrupt Enabled
end sub

Sub OWinBit (Command)
 IntOff
 Dir DQ Out
 Set DQ Off  ' Start time slot
 wait 6 us
 Dir DQ In   ' Release bus for one wire Reception
 wait 9 us
 If DQ On  Then Set Command = 1
 if DQ Off then Set Command = 0
  wait 55 us
 IntOn
end sub

Sub OWout (In Command)
 IntOff
 Repeat 8
  wait 1 us     ' Recovery time between write cycles
  Dir DQ Out
  Set DQ Off  ' Start time slot
  wait 6 us
  If Command.0 On then
   Dir DQ In
  End if
  wait 60 us
  Dir DQ In
  ROTATE Command Right  ' LSB first
 End Repeat
 IntOn
end sub

Sub OWoutBit (In Command)
 IntOff
 wait 1 us      ' Recovery time between write cycles
 Dir DQ Out
 Set DQ Off
 wait 6 us
 If Command.0 On then
  Dir DQ In
 End if
 wait 60 us
 Dir DQ In
 IntOn
end sub

Sub MasterRST (optional command=0)
 IntOff
 Dir DQ Out
 Set DQ Off
 wait 480 us
 Dir DQ In
 wait 86 us ' 70 us default: tested low 30, High 143; at home: (143-30)/2=56+30=86
 If DQ On then ' No sensor(s) found
    command = 1
 end if
 wait 394 us '410 us default: tested 394
 if DQ Off then ' line still low after end time slot: shorted?
  Command = 2
 end if
 IntOn
end sub

[Theo]

Variable DB changed into _DB, thanks to Anobium.

[jackjames]

Beautiful !
Tomorrow I try it!

[jackjames]

I bought it for pic16f877a and i got these errors:

[Theo]

@jackjames

There seems to be an issue with the compiler, I get the same kind of errors during compiling with a PIC. (i don't have PIC's , so I didn't try it before). So far no problems with AVR.(knock on wood!)

Perhaps Anobium can take a look at the problem.

Theo.

[Anobium]

DB is for reserved ASM.

Please change DB = DB/2 to _DB = = _DB/2

Something like:

    _DB=ROM_NO(index)
    Repeat 8
      FB = (_DB XOR crc) AND 1
      CRC = CRC/2
      _DB = _DB/2
        .....

[Theo]

Thank you Anobium, I discovered the same, but the reason was unknow to me.
Perhaps extend the compiler with an error message which tells you the name of the variable that is causing the problem?

Theo.

[jackjames]

Changing the variable name the compilation problem has been solved