I guess I am new here but I was registered before, perhaps under another name.
I have a project where I want two way communication. In one direction I want to monitor between three and six DC Voltages with a high or low indication (+12VDC or Ground). LEDs would be ideal for this. In the other direction I want to be able to control one relay, holding it either open or closed. A simple switch control would be nice, perhaps with a third LED at the switch end to show the state of the relay.
This will be used while driving and at night so I specifically do NOT want to use a cell phone for one end. That would be clumsy and dangerous. I am thinking of two Arduinos probably connected via Bluetooth. But will consider other 2 way radio devices. Infrared or visible light linkage is not a good choice as this will be used outdoors.
I would like a starting point. I think the least expensive Arduinos would be OK, but will listen to other thoughts. I have an Uno and one other but can buy more. And a Bluetooth module (I assume I need two) that can provide the needed functionality. And, of course some sample code, if that is possible. Thanks in advance.
Since you you already have two Arduinos, and there is nothing to suggest Bluetooth is inadequate, you might as well get a couple of HC-05 and use them.
So, would both Arduinos be in the same car, or would one be in the car and one at some manner of base station? Please paint a clearer picture of the project.
The project is to monitor a headlight problem. I would have one end under the hood and the other end at the driver's location. I am getting too old to crawl under a car so I have tried to get someone to run a multiconductor cable for this, but all the auto shops I have asked have refused. I think it is a legal liability thing. The problem is very intermittent. Sometimes they work perfectly and others they will not work at all. And there is no intermediate situation, like dim but working. Just ON or OFF. The dealer wants around $1000 to change out a "module" but will not guarantee that it will actually fix the problem. So I want to properly troubleshoot it. I am also coming up on a mandatory vehicle inspection where the lights must work.
So I want to try wireless. And I want something flexible enough to allow monitoring different things at different places. I also do not want to be driving around at night with no headlights so I want an over-ride capability to absolutely turn them on. I also may want to hang small photocells in front of the lights to know when they are actually on or off.
The big problem with wireless is the metal body and firewall which separates the engine compartment from the passenger area. I hope to be able to use an external antenna on at least the engine's end. I could bring it out and tape it on the outside of the windshield.
The other option would be to just run the cable on the outside of the car. But it would need to pass the hood and the driver's door. I am not sure how that would work out.
Ok, very good. then Bluetooth is probably a good choice, provided the EM noise of the car does not interfere.
ESP32 is a quality and inexpensive choice for this application, in my opinion. Others have recommended them as well.
You could also consider hardwiring between them if there is an issue.