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[wxsig] Humidity and Pressure Sensor Support

Clay Cottingham Clay at Cottingham.net
Sat Feb 26 20:56:29 UTC 2005

Phil -

I have the 8570 running and, as you said, had to re-wire it to make it work.

The spec sheet on it states that it has calibration data that needs to be
downloaded to the host and used to calculate true pressure. I notice that it
is reading 1.87 inches low compared to the local airport. Are you having to
correct for yours?


-----Original Message-----
From: wxsig-bounces at lists.tapr.org
[mailto:wxsig-bounces at lists.tapr.org]On Behalf Of Phil Reid
Sent: Sunday, February 13, 2005 11:09 PM
To: TAPR Weather Station SIG Mailing List
Subject: RE: [wxsig] Humidity and Pressure Sensor Support

Hello all,

Utilizing RJ-11 connectors, the one-wire bus should be as follows ....

 	pin 2	--	ground
 	pin 3	--	1-wire data
 	pin 4	--	1-wire ground
 	pin 5	--	pwr +5 VDC

When I first assembled the TAI8515 ver. 2.0, with the T-238, it required
pin 2 to have power and pin 5 to be ground. I modified the T-238 to
match the TA8515. This was an error. I should have modified the TAI8515
to match the T-238 which is layed out correctly for the one-wire bus.

Acquiring the TAI8570 and putting it on the modified one-wire bus, I got
the same message Jerry received, and scratched my head for a couple of

I acquired the RJ-11 connection specifications for each device and I
realized what had taken place.

I returned the T-238 to its original design, and modified the TAI8515 to

I now have the T-238 with the latest firmware, supporting and powering
the TAI8570/Barometer, TAI8540/Humidity, TAI8585/Counter with rain
gauge, and a TAI8515/Anemometer, all on the one-wire bus.

73's     phil/w7oze

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