Servers by jDrones

Building a Raspberry Pi 4 + Pelican Case ground station computer for Mission Planner

I wanted a device to run Mission Planner on, but which was more suitable for use out in the field than my Surface Go. I’d seen a lot of Pelican 1150 ‘cyberdeck’ style luggable computer builds recently & already had a spare 1150 case, so I thought I’d have a go but with my own particular spin on things. Now that Mission Planner is trivial to get running on a Raspberry Pi 4, this sort of project becomes a lot cheaper & more straightforward!

Being able to see the screen outdoors in sunlight, as well as having a decent resolution to work with, were both key. So instead of using something like the 7" Raspberry Pi touchscreen (800x480?!) I opted to use my 5.7" 1920x1200 HDMI field monitor. I wanted to be able to remove the screen relatively quickly for times that I want to use it back on my camera, which dictated some of the layout choices. I also chose to recess the surface down to the level of the Pelican case’s standoffs, both for structural reasons & so the edges of the case would serve as a sun shield.

I wanted power to come from an XT60 connector & to support a wide range of voltages. I never carry a USB C power bank with me when I’m out flying, but I will always have a bunch of 4-cell & 6-cell LiPo batteries & I have installed an XT60 connector in my car, hooked up to its battery/alternator.

Everything was 3D printed on my Prusa i3 MK3 (on ‘draft’ settings because I’m impatient) using cheap PET-G filament from Eryone.

Rear view with the left (seen from the front) bracket in place, along with speaker, power switch, power wiring, voltage regulators & fan. The brackets are connected to the front panel via threaded brass heat set inserts (I love these things!).

Two LM2596 buck regulators (one set at 12V for the screen, the other at 5V for the Raspberry Pi) with added heatsinks & a 30mm fan blowing out. There are slots above the screen to allow more air into the case, so it’s not relying entirely upon the gaps at the edges & around the connectors.

Tiny 30x20mm oval speaker (Adafruit product ID 3923) & power switch on the left side. The left bracket has spaces to run wires up to the switch/speaker & out the side to the Raspberry Pi.

Rear view with the screen in place, right bracket on & HDMI cable connected/routed from the screen end. Removing the right bracket (two bolts) allows the screen to be slid out & removed for other uses. This flexibility is the main reason I chose not to remove the battery tray from the back of the screen to make space to mount the Raspberry Pi centrally.

Raspberry Pi 4 (4GB) with I2S audio amplifier bonnet (Adafruit 3346) mounted to the left bracket via brass standoffs screwed into more threaded heat set inserts.

5V power connected to the Raspberry Pi via the amplifier bonnet, speaker connected to the right output.

Fully assembled front view with panel mount USB & ethernet connectors. Only one of the Raspberry Pi’s USB 2 connections gets a panel mount connector, because I figured the other is always just going to have a wireless keyboard/mouse dongle plugged into it.

The eyelet at the bottom left allows for the whole assembly to be removed from the Pelican case more easily. All bolts are countersunk for a clean finish.

Fully assembled rear view. Adding the panel mount connectors makes things necessarily messy, but it’s all secure.

Left side detail. There’s even some space left at the top!

Bottom detail of power components.

Now if only I had a working copter with a telemetry radio, the weather would improve & coronavirus lockdown would end so I could actually go out to test it properly!

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I already told you: this is beyond awesome.
The level of detail and the love you put in this project is amazing.

It’s truly what i had hoped people would build after reading my guide!
Well done!

Now that you & Michael have done the hard work getting MP up & running on the Pi, I reckon we’re going to see a lot more projects like this. Honestly I’m surprised at myself that this one came out as well as it did, as I still consider myself an absolute amateur when it comes to 3D modelling for printing!

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Teria como colocar um rotg que recebe imagem na raspiberry pi4 ?

Please use english language so we can all undestand and help, thanks.

Niiiiiice! Congrats !

This whole site is very inspirational but this was the most inspirational thing in a long time :slightly_smiling_face: Thank you @cjdavies
Can you consider to share your 3d print design file?
Should help speed things up not to start from scratch.
Best
/Karl

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@cjdavies This is beautiful and just what I need. Very nice work. Can I trouble you for the sources of some of the other components here? Specifically the rocker switch, fan, M3 bolts, and generally your choices for wire guages? Thanks very much.

These are the specific parts I used, but don’t necessarily take that as a recommendation - these are generic parts sold under myriad different brand names & will of course be available far cheaper if bought direct from China on AliExpress, Banggood, etc. I was impatient at the time so paid the Amazon tax to get them quicker.

LED rocker switches

30x30x10mm fan

For hardware like countersunk M3 bolts I usually buy in small quantities from eBay sellers, because that means I can buy just the 10 or 20 I actually need at the time, instead of having to buy 100, 500, or however many the manufacturer originally sells them in.

For wiring I tend to use 28AWG for signal wires, 18AWG for low power DC & then larger gauges for high power things like drone battery connections. I exclusively use silicone wire, because it is so much nicer to work with than PVC; silicone wire is substantially more flexible & the insulation doesn’t melt like PVC does, especially when dealing with thinner gauges.

Thank you very much for this, and apologies for the delayed reply. I have a list of components together mostly sourced through Digikey, so we’ll give it a try! Have you had a chance to use yours in the field yet?

I actually haven’t! A mixture of covid restrictions & typical Scottish weather means I haven’t flown anything at all in over 6 months now - I rebuilt my custom Y6 last year with new carbon arms & an Orange Cube & it’s just been gathering dust ever since :frowning_face:

Share some photos of what you end up making with the parts, I’m sure it’s not just me who will be interested to see!

Hoping you can get out soon enough. I’m wondering what you think about the size of the monitor you are using? I’m looking at finding something of comparable size or potentially slightly larger within the resolution requirements for Mission Planner. Thinking a field monitor like you used is indeed one of the better solutions I’ve seen. Thanks.

If I was shopping for a screen specifically for this purpose, rather than using a screen I already had, I would probably look for something around 7" rather than the 5.6" of what I have. I find the smaller size ideal for actually mounting to a camera/gimbal, but for groundstation use I feel something a tiny bit bigger would be better.

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Thanks very much. We have a 7" Raspberry Pi display but will of course need to make some modifications to fit the screen.

@Holly918 thank you very much for the installation guide. Do you perhaps have any display suggestions for a pi ground station?

Hello guys,

@JD_L I can share you my experiences with different displays.
I also was inspired by this post of @cjdavies.
I build a very similar unit using his 3d print design as a base.

I have taken my unit out for many times the last 4 months, mainly on one beach site and on one field that’s sometimes a bit muddy (rain comes). In both cases I have been very happy not to bring my Mac or full sized pc. They were not built for that environment. But this is a low cost rugged alternative.

(+) this display is 7 inch and as large as possible
(+) it has built in speakers
(+) it has one nob to regulate both sound volume and brightness of the display
(+) its powered with 5V from the RPI unit directly. No need for other Voltage.
(+) it will display the complete Mission planner screens.
(+) its a touch screen so possibly you don’t need a keyboard.
(+) it has minimalistic connectors from RPI to Display for HDMI and USB, no cables needed.
(+) cost is really affordable (in my opinion).

(-) my fingers are too big so I need a keyboard anyway. So no need of touch screen.
(-) speakers don’t work soo well in the field, maybe better use RPI built in BT to BT earplugs.
(-) The screen is still too hard to see in sunlight, it helps to make cursor super big.
(-) The unit is bulky to handle either you kneel to look or hold it upright to see.
(-) RPI, you have to struggle for every small service like getting BT to work, time consuming.
(-) the voice com is very important in the field, but default voice is terrible, there are better voices but seems not supported anymore.

I will still try adjust this unit for my needs but I really also rely on my Samsung Android phone that can run QGroundControl.

Hope it helps
K

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@karla thank you very much! Yes certainly, I am working in hot, dry deserts, which are also not great places for a laptop or a tablet really. This does seem like a relatively low cost but rugged alternative. I’m also assuming you can run one of these for quite a while on just a few lipo packs or USB-C packs. Has that been your experience?

Anyway, that is a nice looking screen and I can see now how @cjdavies design might be reworked for a 7 inch screen. The touch capability on our 7inch screen seems to be pretty good, but like you I really need a mouse and keyboard.

Thanks again for your detailed response it was much appreciated. As soon as we get something going I’ll try and post the results here.

I actually think it eats up a LiPo surprisingly fast.
Normally that is not a problem in the field since I have several 3s 5500 mAh and 4s 3200 mAh with me for the fixed wings. maybe its because I use a 4g lte internet dongle as well, I usually also have the fan on 5V but it does not get hot really.
Its lovely to close the lid and knowing sand cant reach it :slight_smile:

The 3d print design can be much simplified to just a one piece flat surface. The RPI and screen is staying in place just by the friction to the case.

Ah interesting regarding the power. Will be interesting to test out. Although I have plenty of LiPos around I’ve also been considering trying something like these USB-C packs: https://www.adafruit.com/product/1566

Going the LiPo route though, what are you using for a BEC in your build? I think I’m seeing that down in the bottom left side of your interior shot. Glad to hear you are not seeing heat problems. I’ve been wondering if something like an Ice Tower https://thepihut.com/products/ice-tower-raspberry-pi-4-cpu-cooler could first fit in the case, but also keep temps low on hot days. Mostly thinking about this option in the case the cooling fan needed to be removed from the face to make space for larger screen, or in the case of using a slightly different design from Back7.co that has no cooling fan on the face.

Again, thanks for the discussion.

oh, so many cool designs :slight_smile:
The BEC is a serious overkill but I like that and also the large range of possible V input.

I think one of @cjdavies design ideas was to let the display sink down in to the box and thus be protected from the sunlight to improve visibility. With too many things inside the box like the back7 designs it will not be protected anymore. Just a thought. I don’t think you will need a case for the RPI. the fan is the smaller 30 x 30 mm version running at 5v.

small note, the fan is not sucking air in to the box but pushing air out. I was thinking this will attract less sand from the beach. And I think it has worked well. The incoming air can come from all around the screen and thus the force is smaller than only had to come from one inlet.

The USB and LAN cables inside the box takes up a lot of the available space in the box. I have failed to find anything smaller than these bulky stiff cables. They are really over sized and clumsy. Solve that and you will free up lots of space.

Another idea is to use the HDMI connection and plug in your FPV goggles. That gives really good visibility in the field. However, when I try launch Mission planner with two screens then it will not load. All other APPs work but just MP do not want to run. My life feels a bit too short to figure out why :slight_smile: so I abandoned this idea. But it might be a small config change somewhere…

Also, I think Pelikan boxes comes in lots of sizes so could also step up a size or two…

Good luck!
Love to see some pictures when you done :grinning:

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Servers by jDrones