Quick how-to on <a href='http://digitemp.com'>Digitemp</a> and the <a href='http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3834'>DS9490R</a> Dallas 1-wire system.

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First, if you purchased the DS9490R (with some temperature/sensor modules), then sucks to be you, as the LinkUSB devices appear to be better, and offer straight RJ45 cabling with no messing around.
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That being said, i haven't had any issues with my DS9490R as yet (using my hokey RJ11->RJ45 cable).
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<b>Step 1 - Make a RJ12->RJ45 cable</b>
<br>Make your rj12 -> rj45 cable (or buy one here: <a href='http://www.embeddeddatasystems.com/RJC--RJ11-to-RJ45-Conversion-Cable_p_28.html'>embeddeddatasystems.com</a>).
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Buy yourself some 6-pin RJ12 modular heads from dicksmith/jaycar/radio shack/etc.
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Get out your trusty crimping tool, that can do both rj11/rj12 and rj45..
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Get a piece of CAT-whatever cable, either cut off the old heads, or use fresh non-terminated cable..
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You need to wire it such that:
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RJ12 Plug<br>
Pin 3 - 1-Wire Data<br>
Pin 4 - Ground<br>
Pin 6 - Power<br>
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RJ45 Plug<br>
Pin 4 - 1-Wire Data<br>
Pin 5 - Ground<br>
Pin 8 - Power<br>
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With Pin 1 and 8 being as in these images:<a href='images/rj12.jpg'>RJ12</a> <a href='images/rj45.gif'>RJ45</a>
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Ignore the rest, just snip the other wires and tape it up or something.
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This wiring config is sufficient to read data from the temperature sensors, not sure about transmitting other data, but we'll see when i come to that.. (apparently you must cross the power pins)
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<b>Step 2 - Compile Digitemp (debian)</b>
Grab up the source code <a href='http://digitemp.com/software.shtml'>here</a> and unpack, <b>make ds2490</b>, then you're done.
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You should have a new binary: ./digitemp_DS2490
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<b>Step 3 - Initialise your shiz</b>
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<pre>./digitemp_DS2490 -i
DigiTemp v3.5.0 Copyright 1996-2007 by Brian C. Lane
GNU Public License v2.0 - http://www.digitemp.com
Found DS2490 device #1 at 001/007
Turning off all DS2409 Couplers
...
Searching the 1-Wire LAN
280F32A801000023 : DS18B20 Temperature Sensor
ROM #0 : 280F32A801000023
Wrote .digitemprc
</pre>
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... aaaaaaaand thats it.
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you can now read from your sensors, oh and hook in other sensors, T sensors etc etc, then just ./digitemp_DS2490 -i again.
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cat your .digitemprd and take a look, basic stuff, you'll work it out.
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<b>Step 4 - manual temperature reads</b>
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<pre>./digitemp_DS2490 -q -t 0
Dec 29 23:57:55 Sensor 0 C: 23.56 F: 74.41

./digitemp_DS2490 -q -t 1
Dec 29 23:59:37 Sensor 1 C: 23.81 F: 74.86

./digitemp_DS2490 -q -a
Dec 29 23:59:42 Sensor 0 C: 23.56 F: 74.41
Dec 29 23:59:43 Sensor 1 C: 23.81 F: 74.86

</pre>
you can work out what to do from there, i might post more here later..
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<br><br>verbose:<br>
<pre>./digitemp_DS2490 -v -t 0
DigiTemp v3.5.0 Copyright 1996-2007 by Brian C. Lane
GNU Public License v2.0 - http://www.digitemp.com
Found DS2490 device #1 at 001/007
Dec 29 23:57:44 Sensor 0 C: 23.56 F: 74.41
  Temp. LSB     : 0x79
  Temp. MSB     : 0x01
  TH            : 0x4B
  TL            : 0x46
  Config Reg.   : 0x7F
  CRC           : 0x0A
scratchpad[0] = 0xBE
scratchpad[1] = 0x79
scratchpad[2] = 0x01
scratchpad[3] = 0x4B
scratchpad[4] = 0x46
scratchpad[5] = 0x7F
scratchpad[6] = 0xFF
scratchpad[7] = 0x07
scratchpad[8] = 0x10
scratchpad[9] = 0x0A
</pre>




<pre>
20091229 - first dump of notes


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