Member Since: 15 Jan 2020
Location: Dublin
Posts: 24
Raspberry PI based satnav / Android auto in Discovery 3
I've had this done for a while now but only getting around to writing it up. I've cobbled together a pretty decent and surprisingly reliable infotainment system based on a raspberry pi using Openauto Pro.
Click image to enlarge
when putting this together I really wanted everything to look factory and to be able to keep the OEM stereo so I wouldn't have to deal with any weird CANBUS gremlins. My original thought was that I could somehow use an OEM satnav and feed video from the raspberry pi. unfortunately, my d3 is a fairly basic spec that didn't come with satnav installed so getting this to work would require a lot of extra hardware and a lot more cost. However, the 7-inch display used in the sat nav is a fairly standard size so I decided I could buy a second-hand satnav display unit strip it out and fit a new screen and use the extra space inside the cage to fit all the electronics.
I researched a lot of 7-inch screens and decided to go ahead with the raspberry pi official 7inch touch screen due to it having the simples and least bulky method to interface with. However, this comes with a problem. the screen itself is the perfect size to fit the satnav but there is a rather large border of useless glass around the outside that would need to be removed. There wasn't much information in the datasheet as to what kind of glass was used so that I could determine how to best go about cutting it. I asked around on some forums but the replies were not helpful. I guess they skimmed over it and read something like "how can I cut my screen to make it smaller" which triggered them. there were also a number of replies about void warranties etc. which were very useful as I would have been expecting a free replacement if I somehow messed this up. The screen is relatively cheap so I decided to just go ahead with it and use it as a learning experience.
when the screen arrived eager to know if my plan would work I dove straight into it with a regular old glass cutter and It worked... on one edge anyways until I messed up and cracked the whole screen. I ordered a new screen and used the broken one for practice I managed to get a relatively clean edge and a working 7-inch touchscreen that fit my sat nav.
it's Crude but it works
Click image to enlarge
Click image to enlarge
I'm not going to go into too much detail here about the wiring and software but I will include a simple wiring diagram below. putting it all together was relatively easy and everything fit nicely into the empty satnav chassis. I also wired the existing buttons from the satnav into the IO header so I can program them to do some functions.
Click image to enlarge
Click image to enlarge
Simple wiring diagram. the stuff crossed out in red is a work in progress and not implemented yet
As I mentioned earlier my Discovery didn't come with a satnav and instead had a cubby hole instead. luckily all the mounts needed are located behind this so I just had to cut it out. it's not very difficult however once you start there is no going back.
I wired the audio output of the RPI into the AUX input on the radio, a microphone to the roof console, a USB cable to my phone holder, connected the power and everything worked as expected.
I initially had some issues with noise on the audio line but this turned out to be a bad ground. I've been using it for about a year now and it's been working perfectly.
I'm currently working on some Canbus software to interface with via an Arduino for this so that I can more control over the air suspension, live diagnostics, and some other stuff but I'm pretty busy these days so that could take a while.
CANBUS interface prototype
If anyone wants to do something similar let me know and I can provide more information
Thanks for looking
Brendan
14th Mar 2021 7:32 pm
Green Land Rover
Member Since: 21 Oct 2017
Location: Stourbridge
Posts: 412
Nice job. Looks neat
Can I ask you a few questions please:
Do you have any problems with SD cards being corrupted?
How do you ensure a 'safe power down? I've had trouble in the past with RasPis corrupted when they lose power suddenlyDiscovery 4 HSE - Aintree Green
Freelander 2 TD4 SE Automatic - Tonga Green
Defender XS - Tonga Green - Gone Now
Freelander 1 Td4 ES Manual - Epsom Green - Gone Now
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Member Since: 15 Jan 2020
Location: Dublin
Posts: 24
I haven't had any corruption so far and when I do it will only take me a couple of minutes to flash a new image onto a new card and be up and running again. I don't record any data to the card so I'm not worried about losing data. however, I do plan on using the PI to record CANbus data and since this will be very write-heavy I plan on using an SSD as my storage instead of an SD card.
As for some sort of soft shutdown I've been experimenting with a small relay circuit driven by the acc from the radio to trigger a pin on the IO that tells the PI to shutdown. this works well but getting the PI to turn on again is a little trickier and less reliable. since the pi is now actually switched of you can't read IO.
I have this wired in at the moment and the drop in power while starting the engine is enough to cause the pi to start up. it's not ideal and i do plan to use a cleaner solution but for now it works.
14th Mar 2021 10:35 pm
SN
Member Since: 03 Jan 2006
Location: Romiley
Posts: 13710
Nice integration - I did the simple Pi composite out to SatNav Screen Fakra connection many many years ago but that was as far as I gotSteve N | 21MY Defender | 08MY Discovery 3 (history) | 06MY Discovery 3 (ancient history)
15th Mar 2021 12:35 am
Green Land Rover
Member Since: 21 Oct 2017
Location: Stourbridge
Posts: 412
Thanks for the extra info Brendan Discovery 4 HSE - Aintree Green
Freelander 2 TD4 SE Automatic - Tonga Green
Defender XS - Tonga Green - Gone Now
Freelander 1 Td4 ES Manual - Epsom Green - Gone Now
Freelander 1 Td4 Kalahari SE - Epsom Green - Gone Now
Freelander 1 XEi - Epsom Green - Gone Now
Member Since: 21 Nov 2020
Location: Canary Islands
Posts: 129
Nice Job. I love Pis, and was considering doing something similar in mine - but having the Pi run "OpenAuto".
In the end I opted for a Android Head unit as I didn't want to add another YACUP (My wifes term for "Yet another crazy unfinished project").
I salute you
P.s. When I was thinking of this, I considered getting a 18650 battery-based pi UPS. this would allow the pi to go into a deeper sleep and almost instantly wake up. Im not sure how you have wired it all in or what your start up times are.
An alternative would be an El Cheapo battery bank from Amazon, permanently wired up to pi and the car - charges when car is on, depletes when car is off.
RE Canbus - maybe look at an ESP32 - everything built-in, and can serve data to the pi over a network connection. Can be used to monitor other things when car is off and send you alerts when battery is low etc..Pre-Production
D3 V8 #264
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Living its life as a 50/50 On/Off road car exploring the Canary Islands
17th Mar 2021 12:42 pm
LandyNoob
Member Since: 17 Jul 2023
Location: Lincolnshire
Posts: 2
I'm loving this thread. I was looking at OpenAuto on a Raspberry Pi 4 using the CarPi hat. It provides everything, permanent live for memory and shutdown circuit which is scripted to boot on engine start and do a full clean shutdown when the ignition is off. It also has integrated Canbus, analogue and digital inputs and a host of other features.
Hardware I'm good with, software not so. If I had the knowledge to program it I would, but I now have a Pioneer head unit with DAB and Apple Car Play. I used an installation kit to retain the existing nav display etc. It was a ballache to fit and still not completely finished. It is not possible to set the clock on the instrument cluster and I have had one canbus error about media which I cleared and it hasn't returned.
This thread got me excited when I saw the last post about using canbus to display 4x4 info as I have the SE which doesn't have 4x4 info enabled. Stupid really as you can simply turn it on in the IID software.
Be great to get an update on this project.
17th Jul 2023 8:19 pm
Ady-:)
Member Since: 10 Feb 2018
Location: Bournemouth
Posts: 50
Very cool, seriously considering doing the same.
12th Oct 2023 5:49 am
carbore
Member Since: 06 Apr 2016
Location: Cornwall
Posts: 545
That's very cool, looks tidy too.
I made a data logger for a racing car a few years back with a Pi. It was mainly built around the sense hat for the 3 axis accelerometers but i added GPS and a Camera and even spliced it into the Tacho (Non ODB car)
I did think about building an off road variant to use the Accelerometers for a tilt sensor but never got round to it.Disco 3: Lotus Elise S1: Ferguson T20: Audi A2
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