DigiTemp v1.7 Frequently Asked Questions Copyright 2002 by Brian C. Lane www.brianlane.com Q. Where Do I buy Parts? www.ibutton.com sells the DS9097U-009 for $10 as of this writing. Go to their online store and look for the Serial Port Adapter Section. Click on the 'Blue Dot and One Wire Connectivity' I order my temperature sensors directly from Dallas Semiconductor at 1-800-336-6933 (http://www.dalsemi.com/sales/credit_card.html) They also have the old style adapter that DigiTemp v1.4 uses available as part #DS9097 or DS9097E described as passive adapters. DigiKey as all of the parts needed to build the passive adapter. See the HOWTO.TXT document for DigiKey part numbers. Q. How do I connect it to the RJ-11 of the DS9097-U Take a look at the DS9097-U data sheet at http://www.dalsemi.com/datasheets/pdfs/9097u.pdf Ground is the pin on the right and data is the pin on the left (using the two center pins of the RJ-11). Even with this information you will probably get it backwards the first time so make a temporary connecting the first time and confirm that you have the correct polarity. Q. How many can I connect? Read the Dallas Semiconductor Tech. Brief on the One Wire Network. http://www.dalsemi.com/techbriefs/tb1.html it covers everything you want to know and more. The limit comes down to wiring, how much you have and how good it is. Other than that you can connect as many as you need. Q. How long can the wire be? Again, read the Tech. Brief above. This depends on the cable. Using better cable will allow you to extend the cable longer distances. Q. I have glitches in my data, what do I do? The first solution is to check all of your connections to make sure they are soldered or well connected. Next, is your cable decent quality? Cat-5 is the best, with twisted telephone cable coming in second. If you are still having problems you should try Using a Schottky diode across the cable's end. Connect the diode reverse-biased with the cathode (the stripe) on the data line and anode on the return. I used a 1N5818 across my attic sensor -- before adding this I was getting multiple glitches per hour. Now I have seen 1 glitch in about 2 weeks. Q. What is the difference between the DS9097-U and the App. Note 74 type of adapter. The DS9097-U adapter uses a serial port to 1-wire conversion chip that makes talking to the 1-wire network easier. DigiTemp v2.x uses this type of adapter (the DS9097U-009 and -S09 both work fine). The old style of adapter (sometimes called passive or App. Note #74) used only diodes and resistors to convert the serial port voltages to the one-wire voltages. Dallas still sells adapters of this type, part number DS9097 and DS9097E that is built on this design. DigiTemp v1.x supports this type of adapter, and include a HOWTO document with instructions for building your own. Q. Which 1-wire temperature sensors are supported? DS1820 DS18S20 DS18B20 DS1822 DS1920 Q. Are 1-Wire HUBs supported? Yes, DigiTemp v2.3 for Linux added HUB support, and v1.7 for Windows added HUB support to the windows branch of the project. HUB support is planned for DigiTemp v1.7 for Linux, as well as a tray icon version for Windows.