Arduino Car HUD Does The Job

Many cars these days come with a basic Heads Up Display, or HUD. Typically, these display speed, though some also throw in a tachometer or navigational graphics too. Of course, if your car doesn’t have one of these stock, hacking in your own is always an option.

[PowerBroker2] developed this HUD in a somewhat circuitous way, but it’s effective nonetheless. An ELM327 Bluetooth OBD-II reader is hooked up to the car, collecting data on speed and RPM. This data is passed to an ESP-32 and Teensy 3.5. From reading the code, it appears the Teensy is responsible for logging data from the CAN bus on an SD card, and running a small OLED display. The ESP32 is then charged with running the LED display that actually forms the HUD. It’s then combined with a 3D-printed housing, some plexiglass, and reflective windshield film to complete the effect.

It’s a build that probably packs in more hardware than is strictly needed to get the job done, but it does indeed get the job done. Other builds we’ve seen use LED strips as a quick and tidy way to get the job done. Video after the break.

17 thoughts on “Arduino Car HUD Does The Job

  1. Never experienced a HUD before, but I’d expect a few things as improvements: the image seems to be focused on the near plane (simple mirror reflection), it would be ideal if the focus point was at least a couple meters in front of the windshield; Bigger mirror and/or smaller mount; a less vibrant color for the mount, a dull black/gray would’ve been better. Other than that, looks interesting and responsive.

  2. It’s hardly a HUD.

    The main point of a HUD is to keep the virtual image with information on the same eye focal length as the outside things driver/pilot look at, to eliminate the need to use eye muscles.

    So, despite the fact of nice construction and programming job, this thing is not very useful, simple LED display on the dash will do the same work with much less waste of time.

    1. It doesn’t sound like you’ve ever tried this approach yourself, so don’t knock it before you have….I have a commercial version of this build – although I dispensed with the supplied plexiglass and just leave it projecting on to the glass windscreen. It’s a huge improvement over dash mounted displays because even though it may require refocussing, you continue to have an awareness of what is going on around you.

      1. You could take a look at a HUD system from old cars. They use complex optics to move the focal point to the distance of at least 5 meters. Once I got hands on Delco HUD module from some ’00 Pontiac – it’s really a piece of optics art.

        Also, I’m familiar with modern aftermarket “HUD” devices. The difference in perception with that old Delco thing is infinite. It is completely different devices. When you use real HUD you see your information right on the road, far away from windcreen in the place you focused at. If you use aftermarket “HUD” you see information on the distance of dash. With aftermarket “HUD”, if you focus at the road, you see displayed info like disgusting blurry cloud out of focus. To read the info you have to change your focus from the road to that floating over the dash digits. I don’t see any significant difference from jush looking at the dash by peripheral vision.

        The HUD idea is to avoid changing focus and keep the eye on road constantly.

        1. It is a big improvement over propping my phone in the window with speedometer app. Something I really like on long drives. It also shows speed limits. Proper optics would be great but is a lot harder.

      2. I’ve done this using GPS. It’s not difficult to make it a true infinity focused hud you just need a convex lens. I used an objective lens from a 8×24 binocular in front of the OLED and about 15cm from the reflecting surface. Downside is OLED is not very bright compared with cry or LEDs

    2. “Heads Up Display”. If your head is up and you can see through it, it’s a HUD.

      Very neat project. Does anyone have a good way to take a molding of the dash to make custom mounts? (Dash and wind shield if you use a regular display and can pre-contort the image to look right reflected from the wind shield.)

  3. I have always been really interested in HUDs for small aircraft/automobiles. I have seen a military trainer simulator that used a lightbox -> Fresnel Lens -> LCD panel -> optical splitter. The fresnel lens did a decent job at making it so the focal length wasn’t too close. I had an idea to use Red LED Laser diodes with lenses as beam spreaders and using a notch filter (notched at the LED frequency) to give transparency in all frequencies except the LED frequency. Good for getting something actually working.

  4. If anyone is planning on building this (or buying a cheap one from China) – do check your local motoring laws, especially if in Europe! Otherwise you may get a nasty surprise in the form of a ticket – many countries have laws that explicitly forbid items in the field of view of the driver or attached to the windshield (OK, this isn’t on the windshield) if it isn’t an original part of the car.

    People got fined for having satnavs and phones there, I can’t imagine that a cop will not ticket you for having this sort of “bricolage” on the dash in front of you. At the very least (here in Europe) you would be asked to show a homologation certificate that this is an approved accessory, ticketed if you can’t produce one and asked to remove the device on the spot or risk the car being immobilized/towed.

    1. You would need pretty sharp eye sight to realise that the commercial product is not an integral part of the car – the screen data is almost invisible to an external observer, and when stationary/parked there’s nothing at all to see apart from a slim black box that blends pretty much seamlessly in to the dash. I think you’d be incredibly unlucky to be attract the attention of the law, and (in the UK at least), a ‘not paying due care and attention’ charge woud be fun to defend given the device’s function. (Also, AFAIK there’s no certification required for accessories used in cars in the UK.)

  5. This looks like something that could attract an $800 distracted driving ticket in my jurisdiction. One would have to convince the officer (or the judge) that it was essential for operating the motor vehicle.

    1. Ive been using an old cell phone with Torque, and an ELM327, as my HUD for several years now. Works flawlessly all the time, and VERY low investment. I know it’s not as fancy as this, but..gets the job done, and very well.

  6. Ok, if you really want it further than windshield distance focus we could always do the old school thing and install the whole unit on the hood like hot rods from back in the day!

  7. He seems to have gone to the trouble of making a pcb for the display yet the free form interface cable is interesting.

    It certainly appears to be in development status. Some refinements wouldn’t go astray.

    Ditch the the red box and put the reflective film directly on the windscreen. Replace the box with a slim line housing in black and integrate the interface cable connection.

    All in all it’s not a bad first attempt

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