Åkes' Digital paramagnetic oxygen sensor

This analyzer uses the Palm PDA connected to a brand new Servomex paramagnetic sensor the size of a fuel cell, the ParaCube. The ParaCube has a PIC processor built in and a serial interface (a TTL level 232). It sends data out at 5Hz and accept a few commands for calibration and retrieval of serial number etc. It is a beautiful device which only has one major drawback, it is rather sensitive to moving, not that it will break but the reading will be affected.

As stated earlier (see the digital fuelcell page) I played with the PocketC (http://www.orbworks.com/PalmOS/) a year ago. When I eventually got myself to buy it on Christmas eve 2001, I wrote a small application that interfaces the serial port, retrieves O2 data, and presents in on a scalable strip chart. 

The code at its present stage (0.92) comprises the following files:

(the 0.92 do not yet have the calibration function implemented.)

PocketGui.txt GUI lib from Klaus Rindtorff rindtorf@us.ibm.com found on the PocketC page 
PocketGuiLib.txt dito
Paracube 092 declarations.txt Declaration and globals
Paracube 092 code.txt Procedures and funtions
Paracube 092 methods.txt Event handler and misc
Paracube 092 main.txt Main program and serial handler

If you are interested in the code please contact me at ake.l_remove_@home.se


The complete unit:
  • Palm
  • RS <=>TTL converter
  • Power supply (9V + 7805)
  • ParaCube
On a slightly better screen shot of the Palm you (might) see the application with a Oxygen over time graph, Cal and S/N buttons as well as the instantaneous reading. 

The update frequency is 5Hz. The scale (as seen in the picture, you simply click on the numbers to change them) is 10 to 30 and the time for a complete sweep over the screen (about 120 pixels) is 1 minute.

The rapid fluctuations seen are due to me shaking the sensor.

The inside of the unit:

The unit contains a 9V battery, an 7805 linear voltage controller, and a TTL to RS level 232 converter (Newport NM232DD).



Last modified 2002-01-14

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All material on this website is copyright 2002 by Åke Larsson. All rights reserved.