I still think the original idea suggested by @amal is the most reasonable approach and is similar to what I have been planning.
I will be building my own implementation which will likely involve using 2 separate readers. One which will lock/unlock from outside upon presentation, and another near the center console which will “wake” (ie provide power to) the key and allow the ignition to turn on and the vehicle to start. I may rework this, but that’s the plan for now.
In my particular vehicle, the key losing power would simply result in a message saying “The fob has left the vehicle”. However, I will completely avoid this issue by using a relay to continue providing power to the key that is switched by the ACCESSORY power lead, which has a signal anytime the ignition is in the on position.
I have another comment related to the thread itself which it will include in a separate post to follow.
Just a separate note on the lifecycle of this thread:
A tragedy of this particular thread was caused by very simple misunderstandings. Amal had offered to do this in a very particular way and the OP took it to mean a very specific thing (possibly misconstruing the plan), and then felt let down and that the plan had “changed” when Amal reiterated the plan, which never actually changed at all.
It seems that the OP thought the key was going to be “paired” to an implant, but that was never stated. The fact that this was going to require disassembling and physically soldering the actual key’s circuitry into another larger circuit doesn’t seem to have dawned on the OP.
This was and still is a great solution, I built something very similar to this to open the gates to my apartment complex by texting a number or making an API http request to electronically “push the button” of a homelink circuit that I salvaged from a vehicle’s sun visor and wiring that into an LTE connected Particle Boron.
It would be awesome if there was some standardized way right from the factory that allowed us weirdos to do stuff like this, but as far as working with what we’ve got, the original plan as Amal suggested is still the best solution.
Assuming an active key, why not make a central control system with just one reader connected to an outside antenna.
Outside scan wakes key and then after half a second, hits the unlock button. Sets state to 1
Inside you can push the drive / go / start button to drive around and do whatever because the key is awake.
get out of the car and scan again, if state is 1 then press the lock button to secure the car, then power down the key, set state to 0.
No need for a second reader.
If you want to get funky with it you can also hit the start button after a beat on the first outside scan… and off again on second scan… but there might be scenarios where you just want in the car… so probably best to just use the standard start button and the boney pokey meat stick attached to you for that.
Partly my fault in the wording as I’m incorrectly using the words reader and antenna interchangeably here which I’m sure happens alot.
That being said, the vehicle will be in shows quite often and the doors left open, a lot of random people getting in and out, so as much separation between the unlocking and the starting is preferable and I like the idea of having to scan specifically to allow starting.
I also have the door handles that can unlock/lock with touch with an active key, so there are more unintended consequences to think through there since the key being inside might cause it to be unable to lock with the key awake, etc.
I won’t have the vehicle back in my possession for another 2 months so I am still thinking through all the kinks and edge cases before I commit to a more final map.