Humidity sensors locking up Henriksen software

splee

Member
Hi,

I'm running the Henriksen 1-wire weather station (wx.sandbox.org) and am experiencing problems with a humidity sensor. This sensor is daisy chained with the Dallas wind/rain/direction gauge, and they are all about 100' from the hub. I've noticed quite a few times that the weather s/w will get into a state of 100% CPU usage, and stops updating. When I look at my logs, I see the following just before it locks up:

05.03.2007 13:51:52 Humidity D70000007D833526: Volt supply below 4.0V (3.7), skipping!
05.03.2007 13:51:59 Humidity D70000007D833526: Volt supply below 4.0V (3.7), skipping!
05.03.2007 13:52:07 Humidity D70000007D833526: Volt supply below 4.0V (3.7), skipping!
05.03.2007 13:52:15 Humidity D70000007D833526: Volt supply below 4.0V (3.7), skipping!
05.03.2007 13:52:22 Humidity D70000007D833526: Volt supply below 4.0V (3.7), skipping!
05.03.2007 13:52:30 Humidity D70000007D833526: Volt supply below 4.0V (3.7), skipping!
05.03.2007 13:52:37 Humidity D70000007D833526: Volt supply below 4.0V (3.7), skipping!
05.03.2007 13:52:45 Humidity D70000007D833526: Volt supply below 4.0V (3.7), skipping!
05.03.2007 13:52:52 Humidity D70000007D833526: Volt supply below 4.0V (3.7), skipping!
05.03.2007 13:53:00 Humidity D70000007D833526: Volt supply below 4.0V (3.7), skipping!
05.03.2007 13:53:08 Humidity D70000007D833526: 10 errors reading Outside H: MLAN OK

10 consequtive errors, then locks up. I know it's a s/w problem, but Henriksen doesn't update his s/w anymore, so I'm trying to figure out why the sensor has a voltage drop spike, as this is what seems to lock up the reading of the sensor. This humidity sensor has it own local 5V regulator, as well as the BAT54C shocttky clamping diode, so I don't understand why it's getting a voltage sag. Has anyone have similiar problems? Thanks!
 
Do you have the Humidity in the chain before the wind instrument?
Is the jumper installed on the Humidity board?

Eric
 
ericvic said:
Do you have the Humidity in the chain before the wind instrument?
Is the jumper installed on the Humidity board?

Eric
Yes, the humidity sensor is before the wind/rain instrument. The jumper is installed, and I am feeding the regulator about 10V DC from a transformer based PSU (not switched PSU).

As a note, I never get any errors reading from the humidity or wind/rain instrument at any other time. Somehow, something happens that causes the internal voltage of the DS2438 to fall, and it all goes to pot after that.
 
Since you are providing external power there is no reason that the voltage should drop below 4.95 volts. I'm wondering if there is some issue with the way wServer is reading the DS2438.

I will see if I can get hold of Arne and see if I can figure something out.

Eric
 
I had another thought to try.

Can you try using the OneWireViewer and see what channel 0 of the DS2438 reads.

Eric
 
ericvic said:
Since you are providing external power there is no reason that the voltage should drop below 4.95 volts. I'm wondering if there is some issue with the way wServer is reading the DS2438.

I will see if I can get hold of Arne and see if I can figure something out.

Eric
That's my thought too. However, I can't figure out why the DS2438 is seeing this volt drop. The thing is, I have two humidity sensors, one home made, and 1 Hobby-Boards. One is in the basement, about 50' from the hub, and the other is outside, 100' away. The basement one is fine, but the one outside is the susceptible one. I have swapped them, and the problem remains outside, so I don't think it's the humidity sensor itself, but something in the environment that is causing it.

I have written to Arne in the past, but I got the story of 'building a new house, 4 kids, two 20 year old cars, no time....' :lol:. It's a pity, since it's really a nice program but could use some updating after 2 years....
 
ericvic said:
I had another thought to try.

Can you try using the OneWireViewer and see what channel 0 of the DS2438 reads.

Eric
Don't have the program, but I'll go looking for it. Does it just read all the data from the DS2438? Arne's program kinda has a mode to do that too, in direct web mode. Here's a current reading from the humidity sensor:

HUMIDITY: Humidity - Outside
Humidity 47.2 %
High humidity 58.4 %
Low humidity 44.7 %
Dewpoint -12.3 F
High dewpoint 6.5 F
Low dewpoint -14.0 F
DS2438
D70000007D833526_VAD
VAD (A/D input) 2.44 V
High VAD 2.77 V
Low VAD 2.30 V

Power supply
VDD (Power supply) 5.00 V
High VDD 5.01 V
Low VDD 5.00 V

D70000007D833526_VSENS
Vsens (Battery current) 6.00 V
High Vsens 7.00 V
Low Vsens 6.00 V

Outside H
Current 3.6 F
High 20.3 F
Low 2.5 F
Type Humidity
Serial D70000007D833526
Samples 8859
Last sample 2 seconds ago
Last error
Hub serial D5000000027FB21F
Hub port Main
Back

You can see the measured VDD voltage from the DS2438's perspective, and it's pretty consistent. After the lockup, when you restart the program and look at the sensor again, you can see the voltage sag, and the time it first occurred, which matches the lockup time.

I'm in New England and it's been pretty cold lately. I know all the components are rated to -40C, but I'm starting to think if perhaps the PSU (which is an indoor unit, but is in my shed) can't take it. I've tried two units, with same results. The thing is, I can go for days where the VDD doesn't vary at all, and then it will lock up, so it's unpredictable.
 
ericvic said:
Can you try using the OneWireViewer and see what channel 0 of the DS2438 reads.
Ok, I found the viewer at maxim, and channel 0 seems to be the VDD voltage, so it looks like the same information that Arne's program provides in the sensor dialog. It reads the same, i.e. 5.00 to 5.01V.
 
Can you try running the OneWireViewer for a few days and let it graph the VDD voltage. Then if you see it sag maybe you can try to see what other factors may be happening at the same time.

Eric
 
ericvic said:
Can you try running the OneWireViewer for a few days and let it graph the VDD voltage. Then if you see it sag maybe you can try to see what other factors may be happening at the same time.

Eric
There doesn't seem to be a graphing option for the VDD (or any of the A/D) voltage. I did watch it for a while today, and I did notice an occasional deviation from 5V, but it always went back to 5V on the next poll.

However, just 5 minutes ago, I happen to take a look at the Wserver status, and it had just started getting errors. I immediately went to the web status screen and monitored the VDD voltage there. It was stuck on 2.5V, and stayed there for the 60 seconds or so it took to error out 10 times and lockup. Upon restarting the s/w, the voltage went back up to 5V.

I wonder if there is something that can cause the chip to internally lock up. I didn't go out to measure the voltage (it's 10 degrees F outside now!), but I can't believe the voltage out of the regulator was 2.5V for 60 seconds. Plus, when I restarted the program, with no other reset of the PSU, the DS2438 came back up fine, with VDD back at 5V.

I may try running the OneWireViewer anyway for a while, just to see if it ever locks up on a low VDD. Even if it doesn't graph it, I can at least see if it's a s/w or a h/w issue.
 
My bad, I forgot that that the A/D doesn't graph.

Not trying to pass the buck but that sounds like it almost has to be a software issue. I don't see how the voltage could drop to 2.5v because the voltage regulator would shut down if the voltage dropped that low. There maybe something strange going on in the DS2438 but since you said you have swapped units and the problem doesn't move then I don't think that is it. Possibly might be the wiring. I wouldn't think it was the temperature because all the components are rated lower than that.

Let me know if the voltage drops with the OneWireViewer.

Eric
 
No buck to pass at all. I appreciate your trying to help, even though it's nothing to do with your boards.

It's hard to imagine how the s/w could read/write the chip in any way that could cause it to lock up with a low voltage reading. I'm inclined to believe it's more an environmental thing. I have three DS2438 based sensors (2 humidity, 1 baro), and it only happens on the outside humidity sensor. It used to happen on the basement humidity one too, but after I added a regulator, it hasn't happened since. It's never happened on the barometer, but that's right by the hub. So, I do think it's related to the 1-wire long run, but can't figure out how else I can stop apparent glitches from locking it up. After all, I don't get any wind/rain instrument errors on the same run! As more of a clue, I've got the VSENS inputs on that outside DS2438 tied together, but I can still occasionally see voltage glitches on that A/D input, which would appear to point to outside factors affecting how the chip works.

It's a puzzling problem. I may try posting on the maxim board, and see if their engineers can shed any light....
 
I have two hobby boards humidity sensors hooked up to Wserver with zero problems. Arne's software has no problem detecting and reading the HB humidity sensors.

They are both connected to the Hobby Boards 6 channel master hub.
I am supplying the master hub with 19 volts.

I am not running 100ft of cable to them, each senosr is at the end of a 25 ft cable on separate channels.

You can see my Wserver screen shots of the sensors here.
http://76.162.4.197/Misc/home/OneWireWeather.htm
 
Well, I've been monitoring that sensor using OneWireViewer for about 16 hours straight so far, and no lock ups so far. HOWEVER, I've noticed several times where the Channel 0 voltage has sagged to match the Channel 1 voltage. So, for example, if Channel 1 (which is the humidity voltage) is at 1.98V, occasionally, the Channel 1 VDD voltage will show up as 1.98V also.

I'm not sure if this is a misread. I've never looked at the 1-wire protocol, but I assume the protocol is error checked (CRC whatever), and that there should be no possibility of getting an errored reading. If it IS indeed reading that value from the A/D, then what could be causing this? I have not so far seen the other A/D voltages dipping at all, just Channel 0.

I posted something to the maxim board as well, but it's moderated, so not sure if I'll see any responses soon.
 
When an A/D reading is taken from the DS2438 you have to tell it if youy want the VDD or VAD but the reading part is the same so I'm wondering if the command to tell it which voltage you want to measure is getting missed somehow. It would seem like that would cause an error but I don't know what kind of error handling either of those apps have in them.

What kind of cable are you using?

Eric
 
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