@unstopp, why don’t you tell us what you are actually trying to make and then maybe someone can make a useful suggestion.
At the moment this is just the usual XY problem
Sure no problem. Bear with me a little.
I already have a product, an ECU (car-related) that installs usually in the trunk of a car. You are able to control some functions of the car from the phone, by using my App connecting to my ECU - via BLE.
Now, I want to add an additional controller, a remote (that I will fabricate, with a Nano inside, buttons and all that), that will sit inside the car, on the dash or near the gear shifter, somewhere driver-accessible. This is an extra part that does almost the same thing as the App - it connects to the ECU and controls the same functions as the App. I add this controller for comfort and aesthetics - it looks good, it’s handy, you don’t have to pull out your phone, connect, and all that.
I can do this “controller-ecu connection” in two ways:
Either micro-usb, my initial thought, thinking it might be the easiest way and also cost-efficient (since I was thinking I can use Nano’s micro-usb connector - but it seems not, I will need an additional micro-usb breakout board in this case). On the flip side, there is a bit more hassle - wires, fixed positioning of the controller, running that wire from dash to trunk, etc.
Or, doing it by bluetooth. This means no more cables, less hassle (you don’t need to take the car apart from dash to trunk for that 3 or 5m micro-usb wire), you can keep the controller wherever, whenever. This sounds great.
However, my fear is that I’m not sure how to handle 3 BLEs in this ecosystem. I haven’t looked too much into this. Now I have App - ECU communication via BLE, so 2 BLEs. I have to figure out how to handle 3 BLEs. The master would be the ECU, the controller and the app are slaves. I’m not sure if the ECU (the BLE) can handle 2 BLE connections (App + controller) at the same time, or if when App connects, the controller disconnects, or if when the App is connected, then the controller is not discoverable, things like that. I have to research a bit more and figure out an user-friendly flow.
This communication is nothing more than sending data back and forth (chars and sensor data).
Hope this makes sense. I really appreciate your guys thoughts!