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Mon Apr 16 15:45:47 UTC 2012


1) The right 1-wire device is there, the DS2438

2) For the conversion, the Bray barometers and their equivalents had both an
offset and gain adjustment such that the barometric pressure always followed
the formula BP (inches) = 27.46 + (voltage*0.429).  That was the BP adjusted
to sea level too.  There were lots of good reasons all of the burden was put
on the BP sensor that I recall being heavily debated at the time, but
certainly from my standpoint of firmware writing, it made things really
easy.  It made calibrating really hard!  Looking at the schematics, I only
see an offset adjustment to the output of the sensor, no gain adjustment, so
I am worried it was designed to a different set of assumptions than the Bray
BP sensor for which the T238 is designed.

So, I think you can make the hardware work, but it would be incredibly lucky
if the SW worked as-is.  Knowing the difference in assumptions, if you were
so inclined I am sure the incompatibility could be addressed, either by
modifications to the sensor for a gain adjustment to match the Bray
assumptions or modifications to the T238 code to match the Bitson sensor
output.  Which do you feel more comfortable tinkering with?  :)  

Again, apologies for not responding sooner.  

will

-----Original Message-----
From: wxsig-bounces at tapr.org [mailto:wxsig-bounces at tapr.org] On Behalf Of
John Vause
Sent: Thursday, June 14, 2012 8:29 PM
To: wxsig at tapr.org
Subject: [wxsig] T238 and Bitson barometer sensor

Anyone know if the T238 supports the Bitson Design barometer sensor that
Hobby Boards markets?

73

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