Sandaysoft

This seems to be the Thread of Fine Offset Goodness, so I'm certain someone here knows the answer -

Are the rain gauge, wind speed and wind direction sensors all "Dallas One Wire" based?

I ask because I'm completely and totally fed up with my Ambient WS-2080 - the receiver loses contact with the sensor array routinely, and it's not like the distance between them is great. It's under 100' and there's a single pane of glass between them. I've had Ambient replace the display/receiver - no real improvement.

But now I'm thinking I can buy an inexpensive microprocessor board, a one-wire/USB converter, and write my own code to read wind and rain data. Add a one wire temperature and humidity sensor, and done. Give the microprocessor a USB wifi adapter, and now I have a sensor array data transmitted to my house wifi, which is where I want it anyway.

Feasible? And if the electrical interfaces to the various sensors aren't one-wire, what are they? Many thanks.

Hi,

No none of the FO sensors are one-wire.

The cabled sensors are based on magnetic reed switches, one pulse per tip of the rain see-saw, 2 pulses per anemometer rotation and an analogue value (resistance) derived from the rotational position of the vane. The external temperature is obtained from the resistance of a thermistor (or the 3080/1 may use a dedicated chip) and I believe humidity is from a variable-frequency oscillator - all measured by the microcontroller in the "transmitter" unit (which may also have a calibration table in a memory chip).

Most of the sensors work reasonably well (temperature spikes excluded) so IMHO the main problem is with the very low cost wireless modules. If you're lucky, even those can work moderately well, but many don't, certainly not near the maximum specification range.

Cheers, Alan.

Rather than try to intercept at the sensors, you might consider doing it at the RF stage. On my 1080 transmitter, the board was laid out into two halves - sensor-reader and RF transmitter. There were only a few tracks leading to the RF transmitter section of the circuit, so I put a logic analyser on the wires, and sure enough there were signals being sent as regular long and short pulses (hi/lo) on these tracks - 88 bits of data as I recall.

I suspect you could hook up (either directly or via a PIC chip if necessary) something like a Hope-RF module to send similar signals at the frequency and modulation of your receiver (though I don't know how the RF on these units is modulated). Perhaps you can do some digging on the forums or inside your base-station to figure out what the transmitter is speaking to in order to figure out your next step.

As for a microprocessor board to WiF?, A Raspberry-Pi with a WiFi dongle would do the job - again I'd suggest hooking into the RF wires, but you'd need to spend some time decoding the low-level sensor-data format. Raspberry Pi boards should be on general sale within a couple of months.

All good fun, but in my experience, any hacking of devices like this usually takes a lot more effort than I first envisage.

Hrm. Interesting, but it means voiding the warranty in a fundamental way. I want to keep the option of sending this junk back and getting my refund (to help defray the cost of better solutions.)

To reduce clutter on the board, let me move the discussion to
viewtopic.php?f=16&t=7320&p=62283&e=62283
in Homebuilt.

I'll keep your suggestion in mind, though.

Gina, very nice photos.
My experience with the vane directions is exactly the same as yours.

To emphasize Gina's comment about the intermediate directions (NNW, WNW ...) being poorly represented, I've attached a plot of the relative probabilities of different directions measured over several days. This is a wind vane from the Ambient WS-2080, which I believe uses the same Fine Offset sensor. As you can see, the chance of a 3-letter cardinal point being indicated is very small - about 3% - compared to the other directions. The system of using 2 adjacent reed switches being closed simultaneously, as an indicator of the intermediate direction, is not working very well. If it were possible to use a stronger magnet, or to move the magnet closer to the circuit board, it might be possible to equalize the direction probabilities.
Thanks,
Darrel.

Hi Darrel,

Welcome to the forum and yes, the vane directional uniformity can be improved considerably by adding a magnet (or two). But the vane needs to be pulled from its bearing to fit it, see this thread from a few months ago. However, I'm now working on a related project which might achieve a similar result by processing the vane data "in software".

Cheers, Alan.

Magnetic sensing has it's problems. The reed relays vary in sensitivity and they open and close at different distances (angles) from the magnet. I spent a considerable time experimenting with a magnet and a set of 8 or 16 reed relays when I was making my own weather station. There was no way I could get proper in-between readings for the 8 reed switches and the result varied with which way the vane was turning.

I wanted to measure wind direction to a resolution of 16 compas points. I also wanted a more stable vane as the one on the Fine Offset stations swung all over the place.

I solved the resolution problem in my 1-wire station my using light sensors instead of magnetic. I used a Gray encoded disc attached to the vane and 4 LED and phototransistor sensors fed to a 4 input 1-wire chip. And I much reduced the swinging about using an aluminium saucepan lid and high power magnet to provide damping.

I stuck with magnet and reed relay for the anemometer which is almost exactly like the FO sensor. Similarly with the rain gauge but the other sensors are totally different from the FO ones.

_________________
Gina

Sorry, no banner - weather station out of action. Hoping to be up and running with a new home-made one soon.

This has been done. Receiving with a Raspberry Pi + RFM12B, or a Jeelink is described at
http://jeelabs.net/boards/6/topics/1203
and
http://www.raspberrypi.org/phpBB3/viewt ... 37&t=14777
And
http://www.sevenwatt.com/main/wh1080-protocol-v2-fsk/

Code for Jeelink (Arduino with RFM12B) is also at
https://github.com/rinie/weatherstationFSK original in http://jeelabs.net/boards/6/topics/1203

Hi,

Welcome to the forum and thanks for those links (which will take me some time to digest in detail).

However, I believe that the following quote from several of the threads is "misleading":

"The Fine Offset weather station switched over to a new RF transmission protocol somewhere in 2012. While the old protocol was a On-Off-Keying (OOK) protocol, the V2 protocol used Frequency-Shift-Keying (FSK). "

As far as I can discover, FO still produce various models using both OOK and FSK and have done so for some years. My "evidence" for this is that my "Clas Ohlson" WH1080 purchased in 2011 appears to use FSK, whilst a very recent "Maplin" transmitter (purchased a few weeks ago) uses OOK. Furthermore, my "old" Maplin WH1080 (c2010) appears to use FSK, whilst the "new" protocol, described by Kevin above (and confirmed by examination of my recent Maplin purchase), is OOK. So the "Maplin" versions appear to have changed from FSK to OOK.

Also, the "Solar" versions (WH3080/1) so far appear to use OOK, since I've sucessfully decoded the three data packet formats ("Normal", "Solar" and "Timecode") using a simple OOK receiver. Incidentally, a Raspberry Pi or Arduino is almost "overkill", I'm simply using a PICaxe chip which cost around £2 and runs off a couple of AA cells.

Cheers, Alan.

Interesting. Is there an easy way to tell the variants apart?

I suspect that the "USB lockup" problem may be related to these changes. It seems it just did not exist until a couple of years ago.

_________________
Jim

Hi Jim,

Sorry, not from the outside as far as I know. Somebody did post recently that his Console reported a "version number" when the batteries were inserted, but I've never actually noticed that. It's not even particularly easy when the hardware is "opened up" because (as shown in previous posts) most of the chips are mounted "naked" directly onto the PCB and covered with epoxy.

Perhaps I should also explain that my "old" Maplin station is my "operational system" which is working fine so I'm reluctant to tinker. I also have a 3080 operating (now quite well) at another location and couldn't resist a "spare" 1080 (868MHz) from Clas Ohlson when they were selling at £40. I don't think I've ever experienced a USB lockup, but I don't run the station(s) 24/7. However the "old" Maplin console is connected for most of the time that my PC is switched on.

I've had little difficulty receiving and decoding the transmissions from the 3080, several LaCrosse temperature sensors and a "new" Maplin FO transmitter, however I've failed to get "useable" data signals from the "old" Maplin transmitter. The (434MHz) receiver I'm using does have both RSSI (signal strength used for OOK detection) and FM outputs, but only the RSSI data appears "usefully decodable".

Due to my failure with the old Maplin protocol, I decided to "look inside" the Clas Ohlson units to see if there were any clues, and was surprised to find some "real" ICs complete with Part Numbers! My investigations are continuing, but these chips appear to be complete "intelligent" transceiver/encoder/decoders with an SPI interface which are very probably running in FSK mode (but they do have an OOK capability). So my current efforts are to try "sniff" the SPI bus to see what the chips are actually doing. There is certainly no sign of any "expected" data signals.

I believe that I have some reasonable photos of these chips so I will try to bring this thread back fully OT in due course (but currently the photos are still "in the camera").

Cheers, Alan.

You can get the complete module from Maplin for the same cost. No need to fiddle about, just replace the complete whole thing.

Pity that was not available 2 yars ago .

Also available are:-
N77NF – spare rain gauge
N78NF – spare steel mast tube
N80NF – spare transmitter (includes built-in temperature and humidity sensor)
N81NF – spare wind direction sensor
N82NF – spare wind speed sensor

I wonder which transmitter type it is

Blue sky and light winds
Philip

Hi Philip,

I've not examined that particular transmitter but all the indications are that it uses the "new" Maplin transmission protocol with On-Off-Keying (and 434MHz carrier of course) as described by Kevin in this thread.

I have examined the N79NF (Transmitter for N25FR station) which uses the same OOK modulation and frequency, but with one data byte less in the data packet (because it has no wind direction sensor), so this (also) appears to be not compatible with 1081 or 308x Consoles.

Cheers, Alan.

Have you a link? Part number is not showing.