[wxsig] Crashing and random characters

[John Bennett]

Guy Story KC5GOI wrote:
> With the back light pin removed, I got several days of run time.  It 
> froze on Wednesday when I was at work.  I am testing a theory right 
> now.  I still have a couple of the original release systems including my 
> personal one.  Since the same processor chip was used I swapped the 
> processor from the T238+ with an older one.  I turned the voltage down 
> to 12.8 on the power supply and am running it stand alone now.  If it 
> stays stable then there is a problem with the T238+ kit a club member 
> assembled.  If it crashes, I am going to return to the plus board and 
> start removing sensors one at a time. I will let everyone know what I 
> find when the freezing stops. 
> 
> Guy
> 
> _______________________________________________
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> wxsig at lists.tapr.org
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> 
OK, I'll throw in my 2-cents worth.

About two years ago I upgraded the original T-238 to the latest 
firmware. While it ran, it seemed to freeze once every week or so. I 
attributed this to some sort of power anomaly or RF getting into the 
1-wire cable.

Then the big one hit. Took out virtually *everything* at the site. Over 
the next month or so I rebuilt the T-238 from the ground up. No damage 
to the T-238 PCB itself but eventually replaced every component except 
the resistors (they were checked with an ohmmeter). I re-installed the 
station at a different site. Had problems again with the unit freezing. 
However this time it was every 24-48 hours. I even tried a different 
MCU. Same results. Same version of the firmware as before. Did 
everything else that has been suggested. Back light disconnected, PS 
from a 13.8V regulated source. Regulator running cool.

In total frustration, I finally decided to drop back several versions of 
the firmware. I believe where I finally landed was version 1.13.x. With 
that version it has worked flawlessly ever since. Will and I exchanged 
several emails on this. After down-grading and it was running in a 
stable manner, I stopped pursuing it. In fact, I could not tell you the 
last time the box was power-cycled. My software uses the 'Peet' mode and 
I process the data within the daemon on the Linux box connected to the 
station. Therefore, the other issues that the firmware upgrade addressed 
really didn't matter.

In both instances, the cable run from the T-238 to the sensors was long. 
How long exactly I don't know. Never measured it. My guess is over 50' - 
maybe even as much as 75'. The previous installation that got hit by 
lightning had a run of 40'. There was a discussion thread on cable type 
and length some time back. From what I remember it lead me to suspect 
there is a timing issue somewhere causing the problem. If that is the 
case, you may have been sitting on the fence and the aging of components 
has pushed it over the edge. When I went to a longer cable, the problem 
became worse.

Let me emphasize that this is my experience and does not necessarily 
mean it's your problem too. However, if everything else fails, might 
want to consider dropping back to a previous firmware version to see if 
that helps.

73,

John
n4xi