Photos of the insides of Fine Offset sensors.

[AllyCat]

Hi,

Only 6 wires in the RJ12 connector, of which 5 are used. Their functions are labelled on the PCB under the PV panel, see the photo half-way down Page 4 of this thread. Their sequence/function is (or was) :

NC - No Connection
RESET - Undefined, but somehow prevents the Data Packet from the Pod "colliding" with that from the host Transmitter
GND - Common Ground
RAIN - Looped through from the Rain Input socket (to be processed by the host transmitter)
VCC - Regulated 3.0 volts to "charge" the Transmitter Batteries (and receive power in low light levels)
DATA - The fully encoded Data Packet (8 bytes) forwarded to the Host Transmitter

Somewhere I've documented the Data format, but it basically contains Run-In/Framing/Address bytes, 24 bits (22 potentially used) giving the Lux Value in pure binary units of 0.1 Lux, 4 bits for the "UV" Index and a final CRC byte. AFAIK, nobody has established exactly what the (analogue) sensors are, nor how they're read or calibrated (except that there's a failure mode which clearly shows the existence of at least two coarse gain/scale Lux ranges).

Cheers, Alan.

[coofercat]

I've been at it with the multimeter, and have these pins worked out:

1 - ???
2 - +3V (from the battery pack in the main transmitter unit)
3 - 0V (from the battery pack in the main transmitter unit)
4 - Rain sensor (one end of the reed switch, the other is connected to ground)
5 - Internal battery positive (not connected, as there are no battery terminals physically installed in the lux/solar module)
6 -???

I presume pins 1 and 6 are some sort of network between main box and lux box, maybe I2C or SPI or something - although goodness knows what data gets transferred between them.

If anyone has any insights, I'd be very glad of them

[AllyCat]

Hi,

Did you see my post on Sunday, or is your Pod different to mine (in which case I can't help)?

Indeed, the internal battery connectors (2 x AAA) are not populated, but a reasonably simple modification is to install them and add a low-cost "4-pin" 433MHz Transmitter module (connecting data to pin 6) to make a completely "independent" (of the T/H/Wind/Rain Transmitter) sensor-transmitter module (particularly if the THWR transmitter doesn't have the 308x's 6-pin interface). However, then the Pod can't charge the THWR's battery, and occasionally the broadcast packets might collide.

Cheers, Alan.

[watsonm]

the internal battery connectors (2 x AAA) are not populated, but a reasonably simple modification is to install them and add a low-cost "4-pin" 433MHz Transmitter module (connecting data to pin 6) to make a completely "independent" (of the T/H/Wind/Rain Transmitter) sensor-transmitter modu

Which is exactly what I did with mine although I also had to remove the RJ12 connector to fit the transmitter in. Works a treat. I also used rechargeable batteries and connected the battery connector to an old solar collector from some dead christmas lights display. THis keeps the batteries topped up and saves having to dismantle the unit.

The uv panel on top fell off during modification but I believe it doesn't generate a decent amount of power to recharge much.

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https://www.amazon.co.uk/gp/product/B07DJYK29J/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
https://www.amazon.co.uk/gp/product/B07QGQ1VG5/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
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[coofercat]

Thanks Alan / @Allycat - somehow I missed your post before posting mine. Yours was better

I've been able to "see" the data stream somewhat by pushing it into a uart connected to my laptop. I presume the data is not RS-232 format, but at least I'm able to see something happening.

I'm looking to receive the data (properly), ideally using an Arduino. The RadioHead library looks to be able to PLL lock on to data streams of various types, so might do what I need. What I don't have is a logic analyser to look at the data stream to work out how to read it in though. Could I get a look at that documentation on the data format, or can you give me some pointers, please?

I rather like the idea of the RF module modification - that could be handy, although I might just be able to use the cable connection. Either way, I'm still going to have to receive the data stream correctly.

Your help is very much appreciated - thank you very much!

[watsonm]

I recommend RTL_433 to decode the data stream. I run it on a raspberry pi but I believe it will run on the arduino. Even though
it is call RTL_433 you can specify whatever frequency you need (e.g 868 for newer UK weatherproducts ).

It will output the data in a format that is sent to a broker (HiveMQ) or to a file so hopefully you will be able to process it in a python script.

[AllyCat]

Hi,

IIRC the binary '1' is coded as a 0.5ms pulse of carrier followed by a 0.5ms gap, and the '0' as a 0.5ms pulse followed by a 1.5ms gap (but it might be the other way around). I think High bits are transmitted first but can't be sure. From an old program listing I have the declarations:

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; Fine Offset Solar message BYTE offsets: (8 bytes), 2 bursts spaced 120ms 
; EG: FF 7B 90 55 00 00 00 69 = CRC OK 
symbol FOladro	 = 1	; Address (1.5 bytes), ($FF runin first)
symbol FOuvo     = 3	; UV nibble (low) ?
symbol FO55o	 = 4	; Always 55 ? Is there a Low battery flag?
symbol FOluxho   = 5	; Lux top byte (binary) 6 bits ~= 400kLux specified  
symbol FOluxmo	 = 6	; Lux middle byte (binary coded)
symbol FOluxlo	 = 7	; Lux low byte (pure binary unit = 0.1 Lux)
symbol FOlsumo	 = 8	; CRC checksum (CRC-8 shifting left) 

In principle it's possible to program most microcontrollers to act as a simple Logic Analyser for such data, but the ~£10 "Saleae" (up to) "24 MHz" Logic Analysers to use with the Open Source PulseView/Sigrok software on a PC are remarkably effective.

Cheers, Alan.

[coofercat]

Thanks Alan and @watsonm - this is awesome information.

I've got a Saleae on order, so will have a play around with that. I can also see the "RTL_433" functionality is in the RH_ASK driver (which replaces the old VirtualWire protocol), so it looks like it's relatively easy to get all this connected together. I've got a bit of a busy week coming up, but I'll have a crack at all this as soon as I can.

Thanks again folks - really appreciate the help

[watsonm]

Just bought a replacement rain sensor unit to replace my old Maplins unit(circa 10 years old) which has suffered the ultra violet rays and I manage to break one of the fastening tabs!! . It seems they have changed the moulding and added a higher side wall to it. It is the same depth (20mm ) as I was creating from an old grape package from Tescos to fit when it arrived. It also has a very small bubble leveller (on left side on picture) which with my eye sight I doubt I will be able to read!!

Now where did I store those bird dissuader wires!!