PilotAware

British Forum => General Discussion => Topic started by: DavidC on September 19, 2015, 07:54:38 am

Title: Slice of Pi - a simpler construction method
Post by: DavidC on September 19, 2015, 07:54:38 am
I was intrigued by ianfallon's pictures and build of a Pilotaware box using the Slice of Pi adaptor (http://forum.pilotaware.com/index.php/topic,57.msg804.html#msg804) instead of Digole board (or POD module).
Since I'm still awaiting the Digole board in the post from China, I went ahead and got one which I built last night. All good to go.
I thought this was much neater than the other two methods, since it simply plugs into the Pi (although you still need to solder four wires).

Some pictures below show the construction method I used. I stuck the ARF board to the Slice of Pi with four little sticky pads (used for card making) and put some insulating tape over the metal HMDI socket. The whole assembly fits neatly into the standard red Pi box sold with the Pi itself from RS.

Now I just have to find someone else who's got one to see if it really works, although the diagnostic screen messages look promising.
Title: Re: Slice of Pi - a simpler construction method
Post by: trapdoor on September 19, 2015, 08:42:26 am
Think I was probably the first one to use this board after ordering one in for my first build & posted in the 'enhancement requests' thread, but I'll not hold that against Ian who posted his pictures after he built his up.   :D

I'd suggest for mechanical robustness, you use the plastic nut and bolt that comes with the SoP board - it's used as a support 'leg' but because it bears on the HDMI connector on the RPi board needs to be carefully cut down so it sits exactly on the metal can of the connector when the SoP board is plugged on. Even though the ARF board (and the barometric sensor board when embodied) aren't heavy, vibration in an aircraft could make it unreliable. See the pic below for where the bolt is on my build- although mine has moved on from what is shown there as the ADS-B antenna is now co-located with the ARF antenna on the end of the unit.
Title: Re: Slice of Pi - a simpler construction method
Post by: ianfallon on September 19, 2015, 02:01:09 pm
Yes - all credit for first SOP build goes to trapdoor  :)
Title: Re: Slice of Pi - a simpler construction method
Post by: Richard on September 19, 2015, 07:10:56 pm
although mine has moved on from what is shown there as the ADS-B antenna is now co-located with the ARF antenna on the end of the unit.

trapdoor,
    There as been chat about the ADS-B Antenna been the wrong frequency for the reception.  I can now confirm it is and will not work to receive the ADS-B traffic ( If you have managed to receive traffic with your setup, I would be interested to see how you have achieved this. I have the same areal configuration you have in the photo.  Once plugged back into the original supplied ADS-B antenna, all works fine again. Your configuration looks neat so I followed the same line as you. But no luck receiving with the short antenna.... sorry

Richasrd
Title: Re: Slice of Pi - a simpler construction method
Post by: ianfallon on September 19, 2015, 07:36:38 pm
It might not be the most precision instrument but I've seen traffic S of the Isle of Wight from Banbury with my unit on the ground so it's plenty good enough. Using a cheap £8-10 dongle and aerial. I've you're getting nothing then there's another problem.
Title: Re: Slice of Pi - a simpler construction method
Post by: Richard on September 19, 2015, 07:54:54 pm
Ian,
   Sorry.... My post above is misleading.... I was referring to the use of the the small rubber antenna used instead if the originally supplied larger wire areal that comes with the DTV Dongle.   Yes My PilotAware will receive traffic almost from Coast To Coast  (We are on top of a hill in the center of yorkshire) I'm trying to tidy the pilotAware box without have wires poking out every where...
Title: Re: Slice of Pi - a simpler construction method
Post by: trapdoor on September 19, 2015, 08:43:42 pm
With my small antenna (which is effectively a GSM900/1800 antenna) I can get traffic out to the South East coast of S. Ireland!!

See below.

Whilst it's not tuned to the 'ideal' frequency, It is actually better than the supplied antenna in its uncut (untuned) form which is a DVB-T antenna tuned probably to around 700Mhz - verified on my DSO running FFT (effectively a spectrum analyser)

My latest incarnation has the ADS-B antenna at the same end as the ARF antenna - again see the pics...

You really need to make sure that you aren't shorting the input with whatever antenna and adapter you are using as that will kill any chance or getting anything at all. The antenna I use is this one:

http://www.ebay.co.uk/itm/361362426353

I now have two boxes working perfectly with the small antennae, a third in build (waiting on the DVB-T module from China). The plan is (was) to move the DVB-T module inside the case but I'm reasonably happy with things at the moment and I don't particularly want to butcher the RPi to hard-wire the USB. But it's a plan for the future and I think there is just enough room inside the box.
Title: Re: Slice of Pi - a simpler construction method
Post by: Richard on September 19, 2015, 09:57:14 pm
Trapdoor,
    Thank you for your reply.  I have been trying to used one of the small antenners from here

https://www.wirelessthings.net/868-915-mhz-small-rubber-duck-antenna  for the DVB-T

I see the frequses are slightly different to the one you have sugested. I will order the same as you to try to reproduce your very neat solution.
Title: Re: Slice of Pi - a simpler construction method
Post by: N6010Y on September 21, 2015, 05:39:50 pm
Hi Folks,

Just joined the forum and ordered most of the hardware to start my build. A few questions if I may?  Bearing in mind I'm a mechanical engineer and not an electronics guru - clanky answers work better for me!

1.  My set-up will be:  iPad mini with both cellular and GPS outputting the GPS data to PilotAware, and connecting back to SkyDemon via the FLARM option;
2.  I like the idea of using the SOP instead of the other board - looks a nice solution - What mods need to be done to the SOP board prior to using it instead of the Dogole board?
3.  When using the SOP - how does the 3.3 v get supplied to the ARF board?
4.  Is there a step by step guide with pictures (similar to the construction/build pdf file) that shows each step in order to build the unit?
5.  The Wirelessthings ARF receiver seems to be be out of stock - anywhere else I can source one - I've checked eBay and Amazon - no go!
6.  Is it ok to ask more questions as the build progresses !!!!!!
7.  Any other practical advice greatly appreciated!

Many thanks
Title: Re: Slice of Pi - a simpler construction method
Post by: trapdoor on September 21, 2015, 05:58:36 pm

1.  My set-up will be:  iPad mini with both cellular and GPS outputting the GPS data to PilotAware, and connecting back to SkyDemon via the FLARM option;

That's how most of us do it -- but there is now an option to use a USB GPS directly into the PilotAware unit (testing myself at the moment)

2.  I like the idea of using the SOP instead of the other board - looks a nice solution - What mods need to be done to the SOP board prior to using it instead of the Dogole board?

The POD headers that are in a line need to be removed. Unsolder if you feel confident enough and have a decent de-solder pump, otherwise wiggle from side to side a few times and the pins will break off flush(ish) with the PCB. You can then either just leave them and cover with tape or de-solder each pin (what I do).


3.  When using the SOP - how does the 3.3 v get supplied to the ARF board?

There is an on-board regulator. It feeds a set of pads that have a screen printed legend of GND and 3.3V - there is also a 5V pad next to it so be careful which ones you use.

4.  Is there a step by step guide with pictures (similar to the construction/build pdf file) that shows each step in order to build the unit?

Nope. But it's fairly self-explanatory. You just need 4 wires. There are photo's that both Ian Fallon and I have posted. I have attached one below showing my initial SoP board with ARF.

5.  The Wirelessthings ARF receiver seems to be be out of stock - anywhere else I can source one - I've checked eBay and Amazon - no go!

I bought one from Rapid Electronics but they are also out of stock. WirelessThings say they will be getting more 'soon'. Sign up on their website to get an email when they are in.

6.  Is it ok to ask more questions as the build progresses !!!!!!

Yes. We will help if we can.

7.  Any other practical advice greatly appreciated!

Look at what others have done and decide what's best for you. Everyones approach is different but as long as you build to the plan it should work OK. The most important thing is to buy the modules that Lee has stated work. Don't think 'that looks the same, i'll get one of them instead' as it may not work (as per some of the WiFi threads).

Good luck and have fun.

Title: Re: Slice of Pi - a simpler construction method
Post by: AlanB on September 21, 2015, 06:07:02 pm
I used the Pi SOP (not the wireless things) and made the following mods.

The 3.3v pad on the SOP is connected direct to the GPIO socket so broke that link and then fitted a 5v to 3.3v regulator between the 5v pad connected to the GPIO 5v line and the 3.3 input pin of the ARF as the ARF needs more than the 3.3v limited current than the GPIO can supply.

The TX pin is connected direct to the GPIO board and again based on research I broke the link between and put a15K resistor to ground and a 10K resistor in line to protect the ARF input from the 5v  signal as according to the specs on the wireless things website its sensitive to volts.

It might be that the humble pi board, which is slightly bigger but should fit in the case is the better option as I think the connections are already open - others may have more information on that.

I used the XRF document here: http://openmicros.org/index.php/articles/247-xrf-document-index as reference.

not been able to verify if all of this works yet as only just got the ADS-B element working and no way of checking of what I have done works for the ARF.

Sorry for the clumsy description maybe someone has drawn something up in pictures that would help.
Title: Re: Slice of Pi - a simpler construction method
Post by: trapdoor on September 21, 2015, 06:23:43 pm


The 3.3v pad on the SOP is connected direct to the GPIO socket so broke that link and then fitted a 5v to 3.3v regulator between the 5v pad connected to the GPIO 5v line and the 3.3 input pin of the ARF as the ARF needs more than the 3.3v limited current than the GPIO can supply.



That is NOT correct. The WirelessThings Slice of Pod board has a 5v to 3.3v regulator on board. There is absolutely no need to add another regulator and the 3.3v is not obtained from the 3.3v RPi header.

If you look at the photos on this thread, you can see the regulator on the board.

Also the UART on the RPi is 3.3v NOT 5v

https://www.raspberrypi.org/forums/viewtopic.php?f=44&t=9931

So there is no need to clamp the I/O of the ARF
Title: Re: Slice of Pi - a simpler construction method
Post by: AlanB on September 21, 2015, 06:25:27 pm
Sorry Trapdoor I didn't use the Wireless Things SOP I used the PI SOP.

Sorry for confusion  :-[
Title: Re: Slice of Pi - a simpler construction method
Post by: N6010Y on September 21, 2015, 06:37:08 pm
WOW - I got a bit confused there about having to insert a voltage converter, but I'm glad it's been cleared up.

I guess I need to buy the correct SOP board - I didn't realise there were different types - jikes!
Title: Re: Slice of Pi - a simpler construction method
Post by: trapdoor on September 21, 2015, 06:45:48 pm
Makes sense to use the WirelessThings Slice of Pod board because it saves having to pfaff about with a Digole or Power Pod as it has a nice, beefy regulator, gives some mechanical rigidity to the build and allows the easy mounting and wiring of the soon-to-be 'necessary' (but not mandatory as far as I know) Barostatic module.

It's cheaper than the Digole and just order one at the same time as the ARF that you need to order anyway. The mod of the board to fit in the smaller cases is 30 seconds of 'wiggling' the pod headers until they snap off. Or spend 15 minutes unsoldering properly if you are OCD like me  ;D
Title: Re: Slice of Pi - a simpler construction method
Post by: Admin on September 21, 2015, 06:59:02 pm
If somebody wants to document this build procedure
I will happily replace the section in the current build manual.
It would be good to include the barometric pressure sensor
Thx
Lee
Title: Re: Slice of Pi - a simpler construction method
Post by: trapdoor on September 21, 2015, 07:04:57 pm
Happy to provide some photo's for you Lee.

The build is quite self-explanatory but if you can wait a day or so I can probably knock something up for you. I'm on a client site tomorrow so can't get it done then, but Wednesday might be possible.
Title: Re: Slice of Pi - a simpler construction method
Post by: Andy Fell on September 22, 2015, 12:27:54 am
Trapdoor, Looks very neat! 

Would be interested to see what performance is obtained using that stubby antenna for 868MHz.  In my experience they're a bit poor, but we do have a little margin.

Wouldn't surprise me if that is -10dBi or so.  It's not at all critical on the ADS-B RX of course (transponders have plenty of power), but for 868MHz we need to be careful not to compromise our detection range.
Title: Re: Slice of Pi - a simpler construction method
Post by: trapdoor on September 22, 2015, 08:43:51 am

Would be interested to see what performance is obtained using that stubby antenna for 868MHz.  In my experience they're a bit poor, but we do have a little margin.
[/quote

Here you go ...

https://www.wirelessthings.net/electronics-hardware/antennas


Wouldn't surprise me if that is -10dBi or so.  It's not at all critical on the ADS-B RX of course (transponders have plenty of power), but for 868MHz we need to be careful not to compromise our detection range.


Buy one, test it against what was supplied (what I did) and make your choice. Just because the supplied antenna that comes with the ARF is physically longer, doesn't mean it's a 'better' antenna, but its physical characteristics lend itself to a more general use. 'Electrically' (for want of a better word) it is little different from the small helical.

If you find a better off the shelf antenna that fits the criteria (in band, physically acceptable/ short enough and not on a mag base/ cable) let us know.



Title: Re: Slice of Pi - a simpler construction method
Post by: N6010Y on September 28, 2015, 05:21:15 pm
Trapdoor,

Just ordered my ARF board from WT -  :)  About to start the final build (has been running well in receive mode for the past few days).

Have you managed to integrate a GPS dongle/chip and the Altitude module into your builds?  If so can you post some pictures if possible?

Hugh
Title: Re: Slice of Pi - a simpler construction method
Post by: N6010Y on September 28, 2015, 05:23:36 pm
Forgot to add .....

Are both your mini aerials the same make/model?

Hugh
Title: Re: Slice of Pi - a simpler construction method
Post by: brinzlee on September 28, 2015, 10:42:27 pm
I was told today by wirelessthings that they were intending on stopping the production of slice of pod....I had the last 10 but I told them under the circumstances they my want to reconsider that as using these boards makes the construction a little simpler in my opinion and neater. So call them and register a vote if you want the board and I think they'll put it back into production.
Title: Re: Slice of Pi - a simpler construction method
Post by: ianfallon on September 29, 2015, 09:13:05 am
I think the confusion is partly that there is a thing called "Slice of Pi" and a thing called "Slice of Pod"
The latter has the 3.3v regulator built in and GPIO connector and is the one I used.

An interesting thing to note, my friend had a bad SOPod board which only gave 1.7v !
Because we have used the Adafruit version of the Baro sensor, it has a 3.3v output! So we used that to power the ARF ! Seems to work!
Title: Re: Slice of Pi - a simpler construction method
Post by: Richard on September 29, 2015, 11:32:11 am
Hi,
  If your looking for alternative supply for the Slice Of Pod you can get them from here too.

http://cpc.farnell.com/1/1/114594-ciseco-b024-slice-of-pod-rpi-stacker-adaptor.html
Title: Re: Slice of Pi - a simpler construction method
Post by: ianfallon on September 29, 2015, 11:49:47 am
Has anyone tried Slice of Pi (not POD) + POD (or similar) + ARF ?

Another possibility might be:

Slice of Pi (not POD) + Adafruit baro (with 3.3v out) + ARF
Title: Re: Slice of Pi - a simpler construction method
Post by: ianfallon on September 29, 2015, 12:04:33 pm
I had the last 10

10 ! The first PilotWare factory ?  :D
Title: Re: Slice of Pi - a simpler construction method
Post by: brinzlee on September 29, 2015, 12:06:59 pm
I'm using Slice Of Pod, ARF and Adafruit Barometer MPL3115A2.
Very easy to wire up.....one side of the Slice Of Pod has the ARF and the other the Barometer
Title: Re: Slice of Pi - a simpler construction method
Post by: ianfallon on September 29, 2015, 12:24:06 pm
I'm using Slice Of Pod, ARF and Adafruit Barometer MPL3115A2.
Very easy to wire up.....one side of the Slice Of Pod has the ARF and the other the Barometer

Yep same as mine
Title: Re: Slice of Pi - a simpler construction method
Post by: N6010Y on September 29, 2015, 05:58:03 pm
Any chance of a picture of the front and back connections?
Title: Re: Slice of Pi - a simpler construction method
Post by: Pete on September 29, 2015, 07:18:29 pm
Can anyone tell me if they have successfully achieved a reasonable range (i.e. <10NM) using this ( the above ) setup.

If so, would you mind stating what WiFi dongle and antennae setups you are using etc.
I have built several units the original way with Digole Regulator board and ARF with the supplied antennas and range is very poor.

Thanks for any input on this.
Title: Re: Slice of Pi - a simpler construction method
Post by: ianfallon on September 29, 2015, 07:22:31 pm
Any chance of a picture of the front and back connections?

Checkout the Model B thread for mine
Title: Re: Slice of Pi - a simpler construction method
Post by: Pete on September 29, 2015, 08:23:39 pm
Hi Ian

Can you confirm what range you have air to air/ground over the PA 868MHz  frequency?

Thanks
Title: Re: Slice of Pi - a simpler construction method
Post by: ianfallon on September 29, 2015, 09:29:45 pm
Hi - I've not done any air - air tests yet just mine on the ground with other aircraft overhead.
My unit on the ground was not really placed with a great deal of open space around (houses all around). I guess we've seen a range of a few miles but a hopeful air - air will be better. Hope to test this soon and report back
Title: Re: Slice of Pi - a simpler construction method
Post by: Pete on September 30, 2015, 08:22:54 am
Thanks Ian.