Macros For A Mazda

[Arik Yavilevich] recently upgraded his second-gen Mazda’s control console, going from the stock busy box to an Android head unit that does it all on a nice big touchscreen. It can also take input from the handy steering wheel buttons — these are a great option for keeping your eyes on the road and occasionally startling your unsuspecting passengers when the radio station suddenly changes.

The only problem is that [Arik]’s stock steering wheel doesn’t have any media-specific buttons on it. After a short trip to the junkyard, [Arik] had a fancier wheel to go along with the new head unit.

[Arik] doesn’t use cruise control, and those particular buttons can’t be hooked up with reprogramming the car’s computer, so he made them into macro buttons that control the head unit over Bluetooth, using an STM32 black pill board stashed in the glove box.

[Arik] found out that the cruise control buttons don’t ride the CAN bus — they use a resistor ladder/voltage divider and go directly into the ECU. After that it was mostly a matter of finding the right wires and then cutting and re-routing them to make the buttons work on the ACC setting as well as ON. A brief demo video is idling after the break.

Have an old smart phone lying around? Of course you do. Why not make your own head unit?

Props to [Hedgehog] for the tip!

16 thoughts on “Macros For A Mazda

  1. I have one of those Android radios on my motorhome and there is a kit with 2 five button remotes that can be programmed to control different functions of the radio. They are powered by a coin cell each and could easily be hard wired to the stock steering wheel buttons.

    1. Most of those Android radios already have provisions to use the existing steering wheel buttons.
      Well, at least those I looked at and bought one of do, there’s three cables (GND, K1, K2) at the back of them just for that.

      1. that applies ONLY if said buttons actually use resistance to send the commands…many “newer” cars have these wired on CANbus and you either have to buy a very overpriced black box for $50-ish or DIY your own to translate the CANbus packets to resistance.

    1. My legs only start getting sore after 1 and a half hour, and that’s when I remember my car has cruise control.
      And that’s driving a crunchstick.

      People think I’m a madman, but I’m just used to being the only thing actually driving.

      1. 1.5 hours doesn’t get you very far.

        One of the biggest problems with driving without it is you foot and leg getting very sore – you have to hold them in the same position.. Once you’ve done that for a few hours – even as little as 3 – you’ll want CC..

        1. Incorrect. It is you who’ll get a sore leg and want CC. Me personally, for instance, could easily go for 8h with two or three quick stops for food or toilet without wanting CC.

    2. I came to say that, how can you not use cruise control. I’m sure it saves you fuel, and no speeding tickets. Must free up mental capacity to watch for hazards.

      1. I find the opposite – cruise control can’t ease off the throttle because you’re getting to the top of a hill, or roll it on gently because you’re coming to a hill. Or see upcoming traffic situations. Even on the flat, I find that cc takes maybe 2-3mpg off the economy. This is on a 2012 car, so not ancient (but not with all the latest adaptive stuff either).

        i also find that it means you pay _less_ attention to hazards exactly because it has lowered your involvement level.

        1. this turns out not to be the case. Because you don’t have to monitor your speed all the time – so as to not get speeding taxed – and you can move around a bit while driving (instead of your foot and leg getting very sore) you have much better (and less tired) ability to watch what is going on..

          Yes, they can’t predict the next hill, but modern CC handle hills very well, and you can change their levels of aggressiveness, ie not to use breaking down hill (ie just engine breaking)..

          As for fuel economy, my V6 RWD petrol car, once full warmed up, can get 6.2l/100km (or 38mpg for everyone in the USA) with the cruise control on at 115km/h out in the country, and even lower than that on the open plains (down into the high 5s).

          It would take a lot of work – and to do things most people don’t normally do driving (ie continually vary their speed to optimise fuel usage) – to beat the CC fuel economy.. Not counting going over mountains..

        2. If your cruise control has a nice interface, you can seamlessly take control of the throttle as you approach a hill, then let the cruise control take over again at the other side.

          I have found the early 2000s Ford steering wheel buttons to be great. The buttons on a 2008 holden/vauxhall/opel Astra are a lesson on how not to do it – they are hidden on the indicator stalk! You have no visual clue what button you are going to press and if you get it wrong you can falsely signal a turn.

          I’ve used cruise control and both automatics and manuals without trouble. I’d rather have it go a little bit overspeed on the downhill (manual transmission) than arbitrarily downshift (automatic) at random to try and maintain speed.

          1. GM has a knack for terrible cruise control interfaces.

            In the US for decades they combined cruise control, windshield wipers, turn signals, and headlight dimmer control onto a *single stalk.* Slide switch and button on the end for cruise, ring inboard of that for wipers, up/down for turn signals, front/back for dimmers.

            The Ford buttons, while better designed, have similarly not really changed since the mid-70s. At least as far back as 1975 they had wheels with on/off and set accel/coast buttons on the wheel; they added “resume” sometime before 1980. There were cars with that exact arrangement through at least 2015.

  2. Using buttons with a resistor ladder is a somewhat standardized technique for auto radios.
    Many aftermarket ones can map each buttons resistance to a particular action, so they’re essentially universal.

  3. Most aftermarket radios only have one input for steering wheel media buttons. Mine did . Still a big upgrade over the stock head unit. No way I’d bin cruise control though. Just upgraded. Adaptive cruise and auto lane keeping is a total game changer.

    1. – Second on keeping cruise – even if just for if/when you want to resell it…. although if you throw a connector in or something to make it easy to replace stock/cruise function to the stalk, not a big deal if you don’t really miss cruise yourself i guess.

  4. Just here to point out that even the base model Mazdas are pre-wired for most of the accessory packages, including cruise control. I added cruise to my 05 Mazda 3 by swapping out the steering wheel controls for a set with cruise buttons. They hooked straight to the factory wired harness. I also had to swap out the brake switch for one compatible with cruise control(has an extra pin or two). That was it, I pressed the buttons and had cruise control(about a $2000 option when new) in my base model car for no more than $40 in parts.

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