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I would like it to do +10 instead of +1 per button press (the same for minus)?

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    You could program a microcontroller to produce 10 pulses each time you press the button. – HandyHowie Oct 23 '19 at 12:03
  • that's probably actually the only workable solution, @HandyHowie . Good thinking! It would be a little dangerous because .. say it takes 3 seconds for the 10 clicks .. those clicks would keep coming even if you (say) brake'd in the meantime. – Fattie Oct 23 '19 at 14:54
  • Yea thanks guys! I am used a lot to high level programming and I was really curious what my options are when it revolves around hardware (for a real "problem" in my life). Seems like the options are very limited - too bad. I am curious if it will be different in the future of cars :) – PascalVKooten Oct 23 '19 at 20:45
  • @Fattie Some thought would have to be put into it, but it wouldn't take much to connect the microcontroller to the brake switch to know if the brake had been pressed. Likewise you would also need to detect if any other cruise control buttons had been pressed. – HandyHowie Oct 24 '19 at 7:01
  • @HandyHowie - sure, I put in an actual article explaining how to interface with the "CAN" system that cars run on. That's exactly how you'd do it. – Fattie Oct 24 '19 at 12:50
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To answer the question as asked,

My guess is it would be impossible to hack the car computer in that manner, I'm afraid.

Unless some incredibly dedicated hobbyists (why?!?) made a new ECU chipset or such, it's very unlikely it would be possible to change what the command actually does inside the ECU.

It's easy enough to "muck about" with car ECU networks.

For example, you could make it that for a laugh some other button affects the cruise control.

But my guess is it would be impossible to change what the command actually does when you're actually inside the ECU.

If you're already familiar with low-level programming, here's the awesome article to get you started!

Excellent article on the basics of hacking car networks:

https://www.freecodecamp.org/news/hacking-cars-a-guide-tutorial-on-how-to-hack-a-car-5eafcfbbb7ec/

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Suggestion, drop an email to the author of that outstanding article. It's very likely they would have a quick insight in to the very specific point you're asking about.

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    I don't mind at all but I wonder why anyone would downvote? THis is the actual literal answer to the question in the title ! – Fattie Oct 24 '19 at 12:56
  • It is frustrating when people down-vote without giving an explanation. – HandyHowie Oct 24 '19 at 13:53
  • I mean .. "it's not my site", no worries for me! But I'd be happy to help the unhappy reader ;) – Fattie Oct 24 '19 at 14:15
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According to the user manual, the + switch has two modes of operation. If pressed, it will increment the speed by 1, if held, the vehicle will begin to increase speed and the new target speed will by the speed at which the button was released. On this basis, I'm not sure that hacking the switch to make a single press +10 would achieve what you want as you'd probably lose the second mode of operation.

https://owners-manual.mazda.com/gen/en/mazda3/mazda3_8fj4ee16e/contents/05100100.html

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  • Yea, the problem is that holding it does not increase the acceleration of the pressing. Even, rapidly doing single taps is slightly faster than holding it, but you can imagine this is very frustrating when you want to do a big increase. With my last 2 cars not only would it respond to the increases faster, but it would also allow +10 which makes it possible to go from 40-70 without 30 presses. – PascalVKooten Oct 23 '19 at 13:24
  • Agreed, my BMW does a +1 on a single press or press harder and it does a +5. The other option is the use the throttle pedal and hit the Set button when you’re at the target speed. – Steve Matthews Oct 23 '19 at 13:28
  • That's what I'm doing but I want to avoid that. I see this as value delivered from cruise control of not having to do that. The mini I was driving was accelerating fast to a target speed and also had a +10 option... I miss it – PascalVKooten Oct 23 '19 at 14:29
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It's certainly possible to "hack" it via some advanced low-level programming means, but I imagine that it would be very advanced.

The easiest, safest, thing I can imagine would be using some Arduino or RaspberryPi to intercept and interpret both the button press and brake switch, and use either relays or the boards ports to control the "switch" (meaning closing the circuit). Programming that wouldn't be too difficult, but it would be a bit of wiring work, and you may have to dig into the steering wheel quite a lot. The key to safety would be constantly checking for a brake signal to interrupt the throttle increase action.

The major downside to that would be that if the microprocessor stopped working (for any reason) or broke into an incorrect programming loop or crash, then you would have no cruise control.

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  • kyle, you'd just do it using the "CAN" system which car networks run on. it would be crazy to actually cut wires/etc when the plug is right there! I included an article that explains how to do it. – Fattie Oct 24 '19 at 12:51

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