LED strip and uC add some flash to your tail lights

[Dave] spiced up his new 2012 Nissan Juke with a little tail-light amendment. You can see that outlining the rim of the light enclosure is a series of dots. This is an LED strip that he added to augment the brake lights. It’s glued in place, and features side emitting LEDs so that the light will be focused behind the car.

To control the strip he’s using an ATtiny85 microcontroller. It’s the chip on the right, and an optoisolator next to it protects it from the 12V vehicle power which drives the strip (via a MOSFET), and acts as a trigger when the brake pedal is pressed. He wrote a few effects into the firmware. When the lights are turned on, the strip fades up to 75% over about eight seconds. When the brake pedal is pressed they go to 100%. Check out the video after the break (it seems a little weird to us, as the video runs 18 seconds but the audio keeps going… YMMV).

We’ve seen a couple of tail light concepts that flash the brake lights when you stomp on the pedal. Unfortunately the Juke (and all other cars as far as we know) don’t have functionality built-in to sense when you’ve really given the brake a sudden jolt. It makes us wonder if this info could be gleaned from the CANbus?

Comments

  1. Andrew says:

    No “video after the break”.

  2. Ben says:

    Yo dawg, I herd you like microcontrollers, so I put a microcontroller in your tail light so you can compute while you brake

  3. FTWinston says:

    “Unfortunately the Juke (and all other cars as far as we know) don’t have functionality built-in to sense when you’ve really given the brake a sudden jolt. It makes us wonder if this info could be gleaned from the CANbus?”

    Accelerometer?

  4. fartface says:

    “Unfortunately the Juke (and all other cars as far as we know) don’t have functionality built-in to sense when you’ve really given the brake a sudden jolt.”

    Yes it does, it’s called the TPS sensor or the “Throttle Position sensor”.. if you are in a panic situation you take your foot off the gas rapidly to hi the brakes. simply monitor the TPS for a rapid change to off and trigger the brake light before your foot even touches the brake pedal.

    This has been done on automatic cars by hackers for several years now, you can even buy a kit from autospeed magazine for it.

    • my2c says:

      - Great, making even more people break-happy… It’s irritating enough when people brake on the freeway when they could coast to slow down a little due to a car in front, and trigger everyone else behind them to hit brakes just because they see brake lights come one, now we get brake lights even if they don’t push the brakes…

      • dext3r says:

        +1 my2c.

        a sudden ‘step’ decrease in TPS does not imply braking at all.

        if anything i feel there should be a yellow/amber ‘coasting’ light…when a car is slowing down but the brakes are not applied. maybe something like this could help brake happy fools who refuse to just coast, instead of jamming on the gas then jamming on the brake like idiots.

      • deathventure says:

        Reason most people are brake happy in the first place is because they’re tailgating in the first place.

        Then again, most people don’t take that into consideration because getting to your destination is the only thing that counts everybody else needs to get out of the way.

  5. willis says:

    I like the concept of hacking-in automotive features using micro controllers but slapping LEDs on a car generally leaves me unenthused. His videos, from a single vantage point in the dark, aren’t particularly telling in regard to how this affects the look of the car. Still, his LEDs don’t seem to be over the top and blinding like so many OEM tail lights or aftermarket “xenon look” kits. In at least that regard, good job!

  6. Mike says:

  7. Though very cool, it’s actually illegal to alter DOT approved lights. Just letting you know just in case. I’ve ran into that problem when I made a set of clear tail lights for my E30 BMW back in a day.. Though they were right color etc when lit I ended up having to remove them…and pay a ticket.

    Regarding the jolt, you could put an accelerometor on the break pedal it’s self and “predict” that situation.

  8. that1guy says:

    Illegal and not even particularly cool. It would confuse/distract drivers because he didn’t add any delay in to compensate for the slower response of the tails. Also, a microcontroller is definitely overkill if all you’re doing is going between 75% and 100% duty cycle.

    • my2c says:

      - Maybe I’m cranky this morning, but if that confuses someone they really shouldn’t be driving in the first place. LED’s will have a faster response without a delay ramp up, but that would just give the person following behind slightly more time to hit thier brakes if anything, being safer… Some newer models have LED brakelights anyway, so the ‘instant on’ and not incandescent ramp up due to heating is not a necessarily a bad thing…

      • that1guy says:

        I’m not saying it would necessarily cause accidents, but it would be a distraction and it doesn’t really add anything to the car either. The guy who did it can’t even see it unless someone else is driving his car. I just don’t see the point in this hack since it could potentially cause problems, it’s illegal, and it doesn’t add anything particularly cool either. Maybe I’m the cranky one today, I don’t know.

  9. ino says:

    I don’t get the point for an opto-isolator.
    As he’s stating himself, he could have gone with a simple resistor divider.
    Need extra protection ? juste add à zener.

    Opto-isolators are too costly for this kind of use.

  10. Tom says:

    about the flashing under sudden braking, many cars (e.g fiat 500) have this functionality but flash the hazard lights not the brake lights.

  11. DanJ says:

    Does anyone know what the electrical environment is like on the 12 volt power bus of a modern car?

    Years ago when I was into making gadgets for my car I had to worry about voltage spikes on the order of +/- 70 volts as various solenoids and motors switched on and off. Plus noise from the alternator. Those kinds of voltage spikes far exceed the specs for common voltage regulators and could easily fry them.

    Props however to anyone who makes LED brake lights with a higher PWM refresh rate than most current autos. Am I also the only one who is annoyed to see these things flickering?

    • Haku says:

      Regarding the slow PWM of LED rear/brake lights that many cars appear to have nowadays – no you’re not alone in not liking their flicker, with the amount of electronics / microcontrollers embedded in those cars you’d think they’d at least give the lights a much higher PWM duty!

    • Bill says:

      No, you’re not the only one! My wife and I both feel instant nausea when driving behind an LED equipped Cadillac or Murano at night, and a number of other cars merely give her a headache.

      Low PWM rate LED tail lights should be illegal!

      • Alex says:

        Did I miss something, why is PWM being used at all? Surely the LED constant current driver / regulator is used which is a high freq switching regulator in most cases and can easily have its sense resistor shunted for a higher brightness during breaking?

        Wither all the vehicle and EMC regs I am amazed something as simply as low PWM frequency slipped through any net.

      • Whatnot says:

        A few standard silicon diodes in series in front of a LED actually works well as a dimmer I hear, so that’s certainly doable.

  12. George Graves says:

    I bet that voltage regulator is going to be toast soon. No reverse voltage protection.

    EDIT: DanJ beat me to it.

  13. Bubba Gump says:

    I worked on several systems and Mercedes already has patents on extra bright brake lights on hard stops.

    DOT doesn’t like it, it is already on some systems in Europe.

    And yes, as others have posted, it is completely illegal to modify any DOT approved light, be it tail, turn, reverse, or headlight.

    Here is a perfect example, you have a busted plastic tail light housing. You go get some of the red tape to “patch it”. It is only a legal temporary patch. If you get pulled over, you will be issued a ticket and you have a certain amount of time to fix it or you pay the ticket. Ask me how I know. Same rules that apply to broken mufflers apply to lights.

    • Whatnot says:

      hackaday isn’t US alone you know, plus there are always private roads and race/derby cars.
      And in this case he has the approved lights and added the LED as extra, so I’m not sure if that’s illegal in all US states.

      As for patents, since the people bailed out all car companies we collectively own those patents I say :)
      Allowing hackers to hack something together is the least they can do, and I think the patent system actually allows you to use stuff for private use if you don’t sell it.

  14. grindel says:

    Somewhat tangentially,
    The most dangerous driver on my way home has red and white reflective tape on his car and drives 5mph under the speed limit…and SLAMS on his brakes at the slightest provocation regardless of who has creeped up behind him. This has happened to me once and I have seen him do it to others on several occasions. I would love to see this added to his car…either that or a bumper sticker that says, “Beware: Every stop I make is a panic stop”

    • Whatnot says:

      At least 75% of the population is suffering from mental issues I estimate (and I don’t mean this sarcastically), plus half of those are on medication, and I was actually surprised how many people I talked to at some point leaked they were on stuff like prozac and various types of drugs like that. It’s really astounding to see figures on what is really going on in the world and how tough a time everybody is having dealing.
      So I assume the person you speak of might actually have some panic disorder, because you say he added the reflective tape it really seem it’s a panicky person.

  15. craidon says:

    I work with Audi cars on a daily basis. There are multiple CAN buses in a car. The break light sensor does not tell you how strong you are hitting the pedal, but the ESC does. Look for CAN ids less than 0x100.

  16. whats my car says:

    Alright man, extremely amazing guide…

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