The Zen of the 1-Wire Protocol

John Couture

The Zen of 1-Wire Protocol

Well, folks, I finally solved the riddle of how to program the SX and get them to communicate with the 1-Wire AAG Weather Station ... and I fit the program into a lowly SX18!

The 1-Wire protocol is basically a communication protocol to communicate with sensors and devices using only a single twisted pair of wires.· My weather station is over 400 feet from the shop and is working fine.

1. Attached are two routines:
   1. AAG-Search-608.sxb - This program is used to determine the serial numbers of the AAG Weather Station
   2. AAG-Weather-845.sxb - This program is used to read the sensors on the AAG Weather Station.· You'll have to code your serial numbers into the program to get it to work with your instrument.
      ·
2. A couple of notes about the programs:
   1. Although you can combine both programs into an SX48/52, I separated them so that they would fit in an SX18 / SX28.· I do have a version that is combined and working on an SX52 along with a 4-bit parallel LCD.· If there is any interest, I'll clean up the code and post it.
      ·
   2. As per Jon Williams suggestion, I use a serial port to display the output.· In my case I use an RS-485 network but by commenting out the Enable command you have a standard SerOut command that can be connected to a serial LCD.
      ·
3. References:
   1. AAG· Weather Station - about $80
      http://www.aagelectronica.com/aag/index.html?target=p_1.html&lang=en-us
      ·
   2. Articles
      • Search Algorithm for the BS2P, Jon Williams, Nuts & Volts, Apr 2001
        http://www.parallax.com/dl/docs/cols/nv/vol2/col/nv72.pdf
        ·
      • 1-Wire Weather Station using the BS2P, Jon Williams, Nuts & Volts, Feb 2002
        http://www.parallax.com/dl/docs/cols/nv/vol3/col/nv82.pdf
        ·
      • Using 1-Wire Technology in Bench top Instruments, Dan Awtrey, Sensor Magazine, May 2001
        http://www.sensorsmag.com/articles/0501/34/main.shtml - also several other articles by Dan Awtrey on using 1 wire sensors and chips on the Sensors Magazine web site http://www.sensorsmag.com, just search on "one wire"
        ·
   3. 1-Wire Protocol
      • Overview of 1-Wire Technology and Its Use
        http://www.maxim-ic.com/appnotes.cfm/appnote_number/1796
        ·
      • ·Manual - see pg 2 for the family codes
        http://pdfserv.maxim-ic.com/en/an/AN155.pdf
        ·
      • iButton(tm) Overview (basically the 1-Wire philosophy)
        http://pdfserv.maxim-ic.com/en/an/appibstd.pdf
        ·
   4. Open Source References
      • SourceForge - http://oww.sourceforge.net
   
   
   

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
John J. Couture

San Diego Miramar College

Bean

John,
Very nice code.
A very cool application too.
Thanks for posting it.

Bean.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
"SX-Video·Module" Now available from Parallax for only $28.95

http://www.parallax.com/detail.asp?product_id=30012

"SX-Video OSD module" Now available from Parallax for only·$49.95
http://www.parallax.com/detail.asp?product_id=30015

Product web site: www.sxvm.com

"Ability may get you to the top, but it takes character to keep you there."
·

John Couture

Bean,

You and Jon Williams are my inspiration. You two are the "zen masters" in my opinion. I'm just a lowly apprentice.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
John J. Couture

San Diego Miramar College

John Couture

I just realized I referenced "Al Williams" in the source code and meant to reference Jon Williams. My apologies Jon!

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
John J. Couture

San Diego Miramar College

Jon Williams

No problem -- I like Al too! (And no, we're not related)

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Jon Williams
Applications Engineer, Parallax