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[wxsig] wind sensor prob

William Beals will at beals5.com
Mon Feb 19 04:50:42 UTC 2007


John:

Those current numbers look a little suspicious.  The 1-wire bus and the AAG
sensor are totally powered through a single 1.5K ohm pullup and a digital
logic "active high" drive.  The only sensor I know of that requires power
outside that is the BP sensor that does reqire a dedicated +5V wire.  Maybe
you were measuring microamps?  The voltages on that bus do vary quite a bit
due to it being both a power bus as well as a data bus.  If you'd like to
learn more about it, any of the 1-wire device datasheets has a decent
overview of the protocol, for example
http://datasheets.maxim-ic.com/en/ds/DS1990A-F3-DS1990A-F5.pdf.

Good luck on the modem.  The tricky part for that is getting the audio
levels and keying for your radio.  Other than general guidelines, I don't
offer much advice in the manuals.  If you do run into problems post here as
there are quite a few folk who have gone through it before.

I totally understand the frustration!  Having built my stations quite a
while ago, it has been a while since I've gone through the hardware
gyrations, but am going through a new project right now where I've made some
inintended smoke!  It is probably going to take at least 2-3 weeks to get
"basic life" out of it.  Patience isn't my strong point.

will

-----Original Message-----
From: wxsig-bounces at lists.tapr.org [mailto:wxsig-bounces at lists.tapr.org] On
Behalf Of John Yost
Sent: Sunday, February 18, 2007 1:55 PM
To: TAPR Weather Station SIG Mailing List
Subject: RE: [wxsig] wind sensor prob

Latest update,

The voltages at the processor pins for the 1-wire bus are the same at the
connector - maybe I wasn't on the right pins before, it was getting late.

The unit seems to be working fine so far.  I measured the current draw for
the AAG Electronica V3 sensor and, not surprisingly, found it varied all
over.  The
+5 power line ran 20-240 ma and the 1-wire bus is
30-210ma.  Not sure, but that looks like a lot of current for this device.
Seems that the T238 wouldn't want to support many devices if they all draw
this kind of current.

Now, lets see if the modem will send, haven't seen the LED's light yet,
hopefully I just haven't caught them.
  They worked during the circuit test.

This sure has been a fun experience, in spite of the frustration for a
while.

Thanks for any suggestions.

john



--- John Yost <k3yjp at yahoo.com> wrote:

> Tnx will,
> I am using the AAG Electonica v3 weather senors. 
> Modem  board not connected.
> 
> Bus voltage was 4.94, Bat volt = 8.8 from the status screen.
> 
> Measured bus voltage varied from 4.6 to 4.94.  I suspect that the 
> voltage probably dropped lower but my meter isn't fast enough to track 
> it.
> 
> Cleaned the RJ11 and that seemed to help some, got wind direction.
> 
> Poked around on the board and found that the voltage at the processor 
> (pins 23,24,25) is steady at 4.94 volts, but it was jumping around at 
> the connector.
> Redid all the solder joints - no improvement.
> 
> Since the AAG will accept external power and the
> T238
> can supply that power, I connected those lines. 
> Works
> great.  Temp, wind speed and direction and error counters are all 
> zero!  Bus voltage still jumps around as before.
> 
> I'm going to try putting a jumper from the processor to R16 to see if 
> that will improve that connect.
> Also, I need to check the actual value of R16, guess it could be off.  
> Would like to see it work properly before expanding to other sensors.
> 
> Thoughts?
> 
> john
> 
> 
> 
> --- William Beals <will at beals5.com> wrote:
> 
> > John:
> > 
> > It does smell of some kind of intermittent communication error of 
> > some kind.
> > Firstest and easiest thing to try is check things out on your bench 
> > with nice short cables to all the sensors.  If problems are ony with 
> > longer cables, that is a unique debugging strategy.
> > 
> > If the problem is on your bench, then check for standard stuff like 
> > dry solder joints on all the components associated
> with
> > the 1-wire interface,
> > including the connector.  It may not hurt to insert/remove the RJ11 
> > jacks a dozen times in case some flux may be on the connectors.
> > 
> > Something else to check is the 1-wire bus voltage.
> 
> > One of the display
> > screens while you are showing wx data will show
> the
> > bus voltage.
> > Additionally check the bus voltage at the T238 connector and sensor 
> > with a voltmeter, if all are >4.5V life is good, if any
> is
> > low, let us know.
> > 
> > Also, if not done already, ensure minimum sensors
> on
> > the network to see if
> > it an individual sensor that may be messing with
> the
> > 1-wire bus.
> > 
> > Hope that helps, based on your answers, hopefully
> we
> > can get an idea of
> > where to head for round 2.
> > 
> > will
> > 
> > -----Original Message-----
> > From: wxsig-bounces at lists.tapr.org
> > [mailto:wxsig-bounces at lists.tapr.org] On Behalf Of John Yost
> > Sent: Tuesday, February 13, 2007 9:08 PM
> > To: wxsig at lists.tapr.org
> > Subject: [wxsig] wind sensor prob
> > 
> > I just finished up the T238+.  Nice kit.
> > 
> > After a couple of power on-off cycles, the temp sensor has become 
> > intermittent - works for a few cycles then just dashes for a couple 
> > cycles.
> > The wind direction senor stopped altogether, just dashes for it now.
> > 
> > Wind speed works great though.
> > 
> > Also, sometimes it seems to take along time to initialize at the "in 
> > memory of" screen, several minutes.
> > 
> > Voltages look good, heartbeat is strong.
> > 
> > I know its vague info but any suggestions are appreciated.
> > 
> > thanks
> > john
> > 
> > 
> >  
> >
>
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> >
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