Just thought this might be of interest to someone. It a routine to read =
multiple 1 wire DS 18S20's and other 1-Wire on the same bus.


' One-wire multiple temperature sensors for upto 8 DS18S20 although this =
is not the limit.
' Tested on a PROTON Board with a PIC16F877 at 20 Mhz
' Can be adapted easily for any PIC and board. I use Port A.0 for the 1 =
wire
' Bus, and in this program I have already read the ID's with the =
REMARKED part of
' the program using a single device routine.
' Conversion time is 750ms per device as laid out in 1 wire specs, =
although you can
' test for end of conversion if speed is paramount. 5 volts must be sent =
also to power=20
' the devices when conversion is taking place, uses 1.5ma in conversion. =
Can be a permanent supply.
' Three wires needed, GND, Data, +5Volts. This is supplied by the PIC on =
Pin A.1 when converting.
' Also needs a 4K7 pull-up resistor between DQ and 5volts at pic input =
pin.
' I also have an IBUTTON ports to read DS1990's on the same cable, used =
for alarm setting and door access.
' PROTON BASIC PLUS used as its the best around.
' Any comments welcomed.
' dave.stowe@ntlworld.com
' Copyright Dave Stowe, June 2003

  Include "PROTON_20.INC"         ' Standard include for for 20 Mhz PIC =
16F877
 =20
        'Temperature Variables
  Dim Temperature     as Word   ' Temperature storage
  Dim Count_remain     as  Byte   ' Count remaining
  Dim Count_per_c     as Byte   ' Count per degree C
        Dim Dum       as  Byte   ' Dummy variable to pad OWIN
 =20
  'Store Variables
  Dim Rom[8]      As   Byte   ' Storage for the Device ID
  Dim Pointer      as   Byte   ' Used in storing and retrieving the ID
  Dim Memloc       as   Word   ' Where the data is held
  Dim Loop      As   Byte   ' Used in getting data into Rom String
 =20
  'For Displaying the Data
  Dim Sensor       As   Byte   ' General loop counter for amount of =
sensors
 =20
  ' 1 Wire Bus pin assignment
  Symbol DQ =3D PORTA.0       ' One-wire data pin
 =20
 =20
Main:                 ' Main program starts here=20
  Delayms 500         ' Wait for PICmicro to stabilise
        Cls           ' Clear the LCD
 =20
  ' This bit when un-REMed will read Out the ROM ID's to the LCD for =
adding to the CDATA below
  ' Must be only 1 device on the port at a time when reading ID's
  'OWRITE DQ, 1, [$33]
  'OREAD  DQ ,0, [STR Rom\8]
  'PRINT HEX2 ROM[0],HEX2 ROM[1],HEX2 rom[2], HEX2 ROM[3], HEX2 ROM[4], =
HEX2 ROM[5], HEX2 ROM[6], HEX2 ROM[7]
  'DELAYMS 15000
  'CLS
  'GOTO Main
Sensors:
  For Sensor =3D 0 to 2       ' Loop round the Sensors
   Gosub GetSensor       ' Get the Sensor Data
   Gosub Calculate       ' Work out the temperature
   =20
   ' A little line to display the Data, do all the work with the data in =
here
   Print At 1, 1, "Sensor ",Dec Sensor + 1," =3D ",DEC (Temperature / =
100), ".", DEC2 Temperature
   DelayMs 250               ' A small delay so we can see the Temp
  Next          ' and the next one please !
  GoTo Sensors        ' Do it forever

Calculate:
     ' Calculate temperature in degrees C to 2 decimal places (not valid =
for negative temperature)
  OREAD DQ, 0, [Temperature.LOWBYTE, Temperature.HIGHBYTE, =
Dum,Dum,Dum,Dum, Count_remain, Count_per_c]
  Temperature =3D (((Temperature >> 1) * 100) - 25)=20
  Temperature =3D Temperature + (((Count_per_c - Count_remain) * 100) / =
Count_per_c)
  Return =20
   =20
GetSensor:=20
  ' Must have value of which sensor in Variable Sensor starting from 0
  Pointer =3D Sensor * 8 : MemLoc =3D SensorData + Pointer 'Point to the =
Rom Data
  For Loop =3D 0 to 7
      Rom[Loop] =3D CREAD MemLoc + Loop         ' Get the Rom Data
  Next Loop
  High PortA.1                  ' Put 5 volt on power pins
  OWRITE DQ, 1, [$55,STR Rom,$44]        ' Send Match Rom, Rom ID and =
get temp command
  DelayMs 750                ' Wait for conversion
  OWRITE DQ, 1, [$55,STR Rom,$BE]       ' Send Match Rom, Rom ID and =
read the temperature
  LOW PortA.1                    ' Turn off power
  Return
   =20
     =20
SensorData:
      ' This is where we store the Rom ID's, must go in the program last
   ' This is laid out :-
   ' Family ID - 1 byte, Rom ID - 6 bytes, Checksum - 1 byte
   ' ROM ID is low byte first. As read by the routine above.
   CDATA $10,$8B,$D4,$43,$00,$08,$00,$B6
   CDATA $10,$61,$E6,$43,$00,$08,$00,$57
   CDATA $10,$F4,$AC,$43,$00,$08,$00,$59




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