Ever since I started driving in heavy traffic to places I'm often unfamiliar with, I've realized how dangerous it is to glance down at Google maps running on my phone which I always put in a cup holder. It's so low it completely takes my eyes off the road and the phone is just is obnoxious to use doing basic tasks like skipping a song.

Now a normal person would just spend $10 on a phone holder that clips to a vent and be done with it. But that's not good enough for me! That would block air from the vent making it useless. Besides, I'm a computer scientist, I basically have a degree in over complicating things! So I've spent the past few weeks engineering a head unit that should work in any car that has even a little bit of free space on the dash. Apparently it's much trickier than I anticipated (as per usual) but I managed to make something I'm pretty happy with!

I originally planned on taking out my stereo and replacing it with an after market one that had Android Auto built in. That is until I realized the new stereo wouldn't have any knobs or physical buttons, yuck! Also After some more research, I discovered I could install Android Auto onto a Raspberry Pi with a custom OS called Crankshaft. I had a spare 3b laying around so I tested the software with a bog standard monitor. Thankfully the OS could be controlled with a mouse despite being designed for touch screens. It didn't look all that pretty but seemed very functional and customizable. It immediately started Android Auto when I plugged my phone in via usb a to c cable so I wouldn't have to mess with the default UI anyways. Apparently there's a wireless mode using WiFi but I was unable to get that working. The only downside was the boot times. It took 30 seconds to boot but it immediately launched into Android Auto when it was done so I wasn't too concerned about it.

With the proof of concept complete, I started searching for LCD displays. I knew I wanted a display that
1. Looked good. This meant TN/TFT panels were off the list. They have terrible viewing angles and I really didn't want the main feature of the project to look bad or be difficult to see on bright days. I specifically looked for IPS panels.
2. Had a capacitive touch screen. I would have settled for a resistive touch screen if I needed to, but I don't plan on wearing gloves in my car and capacitive screens just feel and respond so much better in my experience.
3. Was at least 7" and roughly 16:9 aspect ratio. My phone screen is already 6" but it's 21:9 aspect ratio so it's not great to use in landscape mode. I wanted something larger and more usable horizontally.
4. Was at least 720p. Most infotainment displays in cars are 480p and I never really liked how soft they looked so I wanted something better.

I cut out different screen sizes to figure out which would fit best in my car

Turns out Android Auto only supports 480p by default and requires you to go into the developer settings to enable 720p or 1080p mode. Unfortunately, small 720p touch screens don't really exist for the Raspberry Pi so I settled on this 7 inch Waveshare 1024x600. It's not 720p so the scaling won't be perfect but it has both an IPS panel and a capacitive touch screens so my two big points were covered. Also, it was guaranteed by the Crankshaft developer to require minimal setup.

I got the display and verified it worked simply by plugging it in! I had all the hardware proven to work, now I needed to attach it to my dash. There's a small, oddly shaped area just above my vents I figured I could use. I sketched out the area with paper then cut a block of MDF to fit it.

I also made the mount for the display out of the same wood, cutting out areas for the tall parts of the circuit board and heat generating components. It took several hours and quite a lot of jig sawing but the result wasn’t too bad. It was a little crooked but I had to take it off and paint it anyways so I wasn't concerned. I plugged everything in just to test it. In order to get the wires coming out the left side, I turned the display upside down. No problem, there was a software setting that would rotate the display. Easy right?

I took the parts down and painted it all, even creating some trim pieces so it'd look a bit better!

I stuck it in my car, putting the Raspberry Pi in the console space (where the AUX input is oddly enough) and left thinking my work was almost done.

But no, since my display was a non-standard resolution, I had to add an hdmi_cvt command to force the resolution in the config file. This meant that display rotation wasn't as simple as clicking a button or just adding 'lcd_rotate 2' (nor all the alternatives of lcd_rotate). I had to look up the manual on the manufacturer's website. I ended up switching from EGL to X11 so I could rotate the display, however the touch input was not rotated. This meant I needed to edit the a conf file for X11 (after remounting the file system as read-write) and manually change the calibration matrix. As a Linux noob it was doable, but very frustrating since it took most of the day to troubleshoot and fix. Finally, I had the rotation of the display and the touch input correct, but there was another, much bigger issue.

The heat. I did some prior research and knew it'd probably get up to 150 degrees Fahrenheit in the car which is, within spec of the display and other electronic ratings. I don't live in a very hot area so I didn't expect it to reach much higher than that. When I measured my car in the middle of a sunny day, the dashboard was 180 degrees! The head unit itself was around 165 degrees. The double sided tape I used to attach it to the dash was barely holding on, but much worse, the display had peeled off the circuit board and was hanging by just the ribbon cable. Even the layers in the LCD itself were separating! I immediately took it inside to cool down but there was already damage to the backlight diffuser so there's a bright patch in the top right corner. It honestly could have been much worse but I was pretty disappointed.

Thankfully it's only super noticeable when the screen is all one color

It was time to redesign the project with heat shielding as the main focus. First, I got my hands on a windscreen sunshield which dropped the dash temperature to a mere (sarcasm) 150 degrees. I then focused on the tape. I figured it was having trouble holding on because the wood was too heavy (1 pound/458 grams) and sticking out too far from the dash creating a lot of torque. I picked up some Lexan polycarbonate (because it was cheaper than acrylic) and copied the shape of the wood. It saved over 150 grams total and brought the display a full inch closer to the dash.

Next I needed a way to reduce the heat impact of direct sunlight. I just took some aluminum foil and covered the back with a few layers of kapton tape. This covered the electronics on the back, and the new bezels I made in the front so even if the display gets too hot, it can't separate and damage itself any more.

I think it looks… unique. Definitely not what I had in mind at the start of this project but if it works then it's not stupid. Razz

I haven't had the chance to drive with it yet, but I left it out on a hot day again (regularly checking it). The tape held and the display wasn't too hot or damaged so I considered it a success! It's a bit askew (again) but I'll be fixing that once I get the newer cables that should fit better. I'm currently powering it from my 12v outlet but I plan on switching to an always on fuse box adapter (with low battery voltage detection of course) if it continues to hold up. I tested the current draw peaks at 1.2A (when booting) but is typically more around 1A and drops to .4A when sleeping.

I'm pretty pleased with how it ended up. It took over 2 weeks of research and building but I ended up with a much safer way to glance at Google Maps, skip a song, and I also still get the full functionality of my vent along with the stereo's knobs and buttons to use! Laughing

I think it's pretty cool that I could adapt this project to just about any car I get in the future. I'll update you guys when I finally get to drive with it!
Nice work, I thought about taking this project on as well to replace my aging Uconnect display in my car. I'll be curious to see how well the device holds up while driving as well as responsiveness!
This is incredible! Having your phone on the dash like this is such an underrated feature. Being able to browse for a location or a playlist while walking to my car and just having the navigation ready to go is next level integration. Yeah, you can do that with a vent clip and a phone but it's not the same to me.

Definitely not what I had in mind at the start of this project but if it works then it's not stupid.

Exactly! Now that you have something that works get back to the drawing board and make a second version that addresses everything you don't like and enhances everything you do like. Looking forward to your future iterations. Perhaps powering the screen off the RPi then using Thunderbolt 3 to carry power (and video)? With wireless Android Auto you could drop the USB to the phone and get away with just one cable to the RPi.

Now a normal person would just spend $10 on a phone holder that clips to a vent and be done with it. But that's not good enough for me!

I went with the "throw money at it and it'll solve itself" approach. I bought a head unit for my car and replaced my radio entirely. A few years ago the USB port on the unit died. It sucked because only that USB port supported AA & CarPlay. By that time Wireless AA and CarPlay were out and I knew I used the feature enough that I wanted it to be wireless.

Best upgrade ever.

I have an iPhone but the wireless processing to the head unit uses so little power that I don't worry about having to plug in. Plus, as a safety bonus, if I'm ever in a crash or accident I know my phone won't go flying out a window or hide under a seat and render me incapable of contacting help; the phone will be securely in my pocket.

It took 30 seconds to boot but it immediately launched into Android Auto when it was done so I wasn't too concerned about it.

Maybe not ideal but I think that's acceptable. When you think about it, the first minute of driving could be leaving your neighborhood, work, a shopping mall parking lot, etc. Aside from a rare occurrence, I don't really need to know where I'm going the first 5 or so minutes anyways. Plus, using your phone to look for a destination as you walk to your vehicle makes the 30s boot a non-issue.

One thing I'm not a big fan of, at least with CarPlay, is that audio controls seem to lag by 4 seconds. Press Play, music starts playing 4 seconds later. Pause, Skip, Back, etc. Audio calls are fine, there's no 4 second lag and Siri would be unusable since I don't even think it waits 4 seconds for a prompt after activation.

As I've incorporated smart home tech into my residence, I can now control only one accessory from my car, and that's my garage door. Which touches on my second safety point.

I love that if my car were to get stolen, the thief wouldn't be able to easily get directions to my residence and open my garage. The built in buttons or the visor clip remotes are a physical security nightmare. Now everything I need is in my pocket. I rent a car with CarPlay? I can still open and park in my garage because the remote is my phone/CarPlay now.

If I get carjacked, I can just leave the car and my phone stays in my pocket. Downside, can't track the car but I think I'd rather have my phone than know where my car is.
Great work on this, TheLastMillennial, and as always, a comprehensive and engaging build log. That's too bad that heat has been such a problem; I would not have expected that! Although you didn't call it out explicitly, it seems like one of the project constraints/parameters is that you didn't want to cut into the dash at all, correct? I'm nervous about that set of cables hanging down near your steering wheel and potentially pedals if they get disconnected, and I'd love to see a v2 where you replace the existing audio unit and tuck the cables away.
Thank you everyone!
I agree with you Alex, wireless Android Auto is the best and it's one of my future goals!

Kerm, I thought the same thing about the wires being too close to the steering wheel (they don't run anywhere near the pedals). I've since replace the ones in the photo with flat ones that run along the dash. They're not perfectly flush but they're out of the way and look much more discrete. I also discovered I don't need the third cable to the display for power, the Pi can power it.

That brings me to the only significant problem with this project, the Pi can't provide enough power for both the display and my phone. If the Pi powers the display, my phone doesn't charge at all. Android Auto does appear to drain the battery somewhat quickly but I'm not quite sure how I'll fix that without running a third cable to the display.

Other than the charging issue, the head unit has been fantastic to use! The tape has held perfectly even if I drive over a rough bump in the road. It also doesn't vibrate at all which is a relief. Waiting 30 seconds for it to boot is a little long if I'm in a hurry but it's not that big of a deal since it reliably turns on maps and my music when it does boot. I'll still look into improving the boot time.

I think the only major change I'd like to do is hijack the skip forward/back buttons that are on my steering wheel and plug them into the Pi. I think I'll have to tamper with the stereo so I'll need to do more research before I attempt it.

I may also get a DAC hat. The Pi's onboard audio honestly isn't bad but I'd like to see if I can improve it. The hats can get expensive really quickly ($40-$120) also I don't really know what to look for in a good DAC so I'm not really sure I want to spend the extra for one right now.
TheLastMillennial wrote:
I think the only major change I'd like to do is hijack the skip forward/back buttons that are on my steering wheel and plug them into the Pi. I think I'll have to tamper with the stereo so I'll need to do more research before I attempt it.

I looked into this brand a while ago for a separate reason/project and found this adapter. Not sure if it'll work for your project but could maybe put you down an already forged DIY path.

The Pi's onboard audio honestly isn't bad but I'd like to see if I can improve it.
It doesn't get you much in terms of advanced audio, but for less than $10 you can get a USB sound "card" (e.g. Amazon). I want to do some voice recognition and generation with my Raspberry Pi 4B, and I'm going that route for audio input/output.
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