Do I understand this well enough? bluetooth car door locks

Projects General Guidance
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Hello everyone,

I would say I'm like a new born when it comes to the arduino boards. I recently discovered them because a friend of mine wanted to make a mame cabinet which we decided a pi would be best.

I have an idea for my own project though. I want to modernize my suv. It's a 95 with no key fob but electric locks. I've already got the wiring diagrams and I know which color is for lock and unlock directly to the physical door lock switch on the driver side(that will work correct?). I have a few questions though because I have not purchased any parts yet. I think I need at least the nano v3.0 as it would hide nicely. I also would want to get a buck converter, at least a 2 channel relay, 4pin bluetooth module and lastly a big set of jumper wires. Does this sound like everything? Update I want ahead and bought a uno r3, some jumper wires, a 2 and 4 channel relay, buck converter, bluetooth module and a connector so I can wire the power plug to the converter

As far as the code, I took 2 courses with python 4 years ago which I hardly remember but I see that scratch appears to be mildly simple. I've not actually tried writing the code yet but I have an idea of what it should do or the logic to it at least after doing some research.Once the parts arrive, I'm going to start attempting to write my code for this. I am looking at the examples provided both online and within the Arduino exe

I basically want the bluetooth module to be looking for my phone. once it establishes a connection, I want it to listen for the command, (Lock)(lock)(L)(l) or (Unlock)(unlock)(U)(u). An app that would send those commands in a button layout instead of a terminal would be great and I think I've seen a few around but I want it pretty simple.

When it receives the unlock command, it will trigger relay 1 to provide power to just the single unlock wire for .5 to 1 second which will act as if I were physically pressing the unlock button on my door right? The only trouble I may have is that with a single press it unlocks the driver side and a second unlocks all doors. Not sure how much a delay I would have?

When it receives the lock command, it will trigger relay 2 to provided power to just the single lock wire for .5 to 1 second (I'm not sure on the timing yet) which will lock all the doors. (maybe later on, have it beep my horn to confirm or send a confirmation to my phone)

I also want to retain the physically buttons in my suv as well, but I have seen/used connectors that splice into a wire while leaving it intact. Would that cause any type of feedback issue or would the relays being in place protect the arduino?

If I can get this working I'd like add features to it like unlocking my rear hatch or even remote start. I can always buy a 4 or 8 channel relay later on. Anyways, that is my basic idea. Does this sound like I am on the right track? Does it sound like there are any flaws? I would appreciate any and all advise or criticism

I added the diagram with how I basically plan on connecting it so you guys have a better idea of my setup.

basic idea.png
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A switch has a least 2 connections. Your relays also deserve such a second connection, to ORG or whatever the other switches are connected to.

You can find out whether your idea works, by using manual switches instead of the relays. Then find out how long a switch must be pressed, and write code to do that with relays. The Serial input can be used to control the Arduino so far. Once that works, a BT module can be added.

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I basically want the bluetooth module to be looking for my phone. once it establishes a connection, I want it to listen for the command, (Lock)(lock)(L)(l) or (Unlock)(unlock)(U)(u). An app that would send those commands in a button layout instead of a terminal would be great and I think I've seen a few around but I want it pretty simple.

You may want to do this just for the intellectual exercise, or because you can't think of anything better to do but it might be worth your while to try harder at the latter.

As is always the case with anything to do with a phone, the first thing to do is check the feasibility at the phone end. What you are looking for is Arduino auto-connecting with the phone. While a bluetooth module can autoconnect with another bluetooth module, I'm not aware of a controller app that allows you to autoconnect to a phone. There is swag of controller apps that could do the job, but you have to turn on the phone and fartarse about getting the connection, in the rain, and in the meantime your girlfriend has gone off with the guy who opened his Corolla with a key.

Since you can have bluetooth modules auto-connect, you may indeed find you can do what you want a lot better without an arduino, and without a phone either.

I think you would be better off spending a few dollars on a remote door kit with a one-button fob, and keeping the Arduino for something more useful.

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I have looked at the remote kits before but this is more just a fun project that I can customize to my liking. Also I'm prone to locking my keys in my suv but I never forget my phone so that was the original idea that started this really. Yes, I have a spare key, but I leave it at home so this is a better solution for me than a "hide-a-key" or key fob.

I won't need an app to toggle bluetooth on as I always have it on ( I bought a 9300mAh battery for my phone so it lasts 3 days with heavy usage and a back up battery when that one has to charge :P). I assumed by the time I got close enough to want to unlock my suv, my phone would already be connected. All I would need to do is launch the app and tap the button or enter u or l with a terminal. This should work shouldn't it? My phone usually connects to my other bluetooth devices quickly once they are powered on. I do also want to retain my original door locks and key functionality.

I'm also considering when it locks to honk the horn and flash the blinkers once. After I understand it better, I'd like to try a basic toggled alarm and remote start. Possibly integrating the uno with a pi "carputer" eventually too for multi media, gps, back up cam, etc.

I would like to reiterate this is my first project so I'm really just getting my toes wet with the capabilities. I'm very anxious to have my hands on the hardware.

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s10lowrider:
I won't need an app to toggle bluetooth on as I always have it on ( I bought a 9300mAh battery for my phone so it lasts 3 days with heavy usage and a back up battery when that one has to charge :P). I assumed by the time I got close enough to want to unlock my suv, my phone would already be connected. All I would need to do is launch the app and tap the button or enter u or l with a terminal. This should work shouldn't it? My phone usually connects to my other bluetooth devices quickly once they are powered on.

Everybody has bluetooth on, but having it on is not the same as having it connected. Further, just because your phone auto-connects to your car radio, it doesn't mean it will auto-connect to your lock system. That's an app, not the phone - hence my comment about checking the app. I can't comment on controllers, but every terminal app I know of requires you to manually connect. And while you are considering that, if it did auto-connect, how will it disconnect so that it can talk to the radio? It all sounds rather tedious and over-complicated, and in the meantime your girlfriend has gone off in the Corolla, and your wife is trying get you on the phone.

While all this is going on, the Arduino side of things is pretty simple but, as I said, you should be able to do this without an Arduino and I imagine that applies even if you do use a phone.

Get your feet wet, by all means and have your Arduino more usefully employed, but spare us the horn honk, it's so 1990s you only see it in old movies.