Make your own free website on Tripod.com

SHT11 cheap 1-wire USB PC (W 98,Me,2K,XP) interface for up to 50 SHTxx sensors


          Hardware:

  • one DS9490R ($13.75), USB bridge with  1-wire RJ11 interface

  • DS2406P ($4.65)

  • SHT11/15/71/75 ($10.00 - $20.00)

  • flat 4-wire telephone cable


Software

  • Visual Basic 6.0 run-time files VBRun60

  • mscomctl.ocx  (google, the file should be in the \Windows\System(32) folder, you might have to register it, click the Start button, click run, type regsvr32.exe mscomctl.ocx

  • 1_Wire_Drivers  v400b3

  • SHT 1-wire

 

Remarks:

  • use the outermost conductors for the 1-wire data and ground, do not connect the inner conductors, use local power supply or seperate cable (and 5V regulators), see microlan design guide.  This way a distance of 60 meters is possible. The network might get much longer using DS2409 microlan couplers, or an  opto isolated 1-wire bus

  • In the   SHT 1wire.exe directory a file th.txt will be created. Individual lines look like:
    001 T date time MSB LSB CRC CRC-calculated flag
    001 is the number of the sensor, T/H temperature/humidity, MSB most significant byte, flag is a space when CRC's are equal, otherwise a "0"

  • On a P2/450MHz/64MB CPU/memory usage is 4%/10M

  • A serial interface for one SHT.. :http://peterpolm.tripod.com

  • Questions: peterpolm@yahoo.com