Communication between multiple devices

We are looking for options for our kid’s project. we would like to have some kind of module that is compact to put on a bunch of slow RC cars that detect each other’s proximity and turn on a light that is mounted on top when a set distance between each other is breached. we would prefer a stand-alone module or a module that can piggyback off a wifi network or a type of BLE system without the need of an Anker. we are open to options. clear as mud I know lol.

First thing that comes to mind is the Edison robot.
The IR messaging between Edison robots may suit what you want for your RC cars.
Might be worth looking at the pack below, comes with 2 robots.

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probably more questions than answers, so I’ll start with them:

  1. have you got the cars?
  2. how many cars and how big are they?
  3. is it proximity all around the car? e.g. 360 or just in front etc
  4. How comfortable are you with electronics? soldering etc

The cheapest proximity sensor is probably HC-SR04 Ultrasonic Module Distance Measuring Sensor | Core Electronics Australia it works a bit like a bat, emits a ping (sound) that gets reflected back. The problems are that it’s only got a 30 degree field of view and you could have issues with interference multiple cars pinging at the same time.

The interference could be solved by pinging at a regular interval and make sure (hope) that the cars aren’t synchronised. It’s only got a range of 5m, so, if anything is within that range you’ll get a response in about 30ms, so, as long as you set it up right you have each car not overlapping you should be OK.

The really hard part is the directionality, you could solve that with multiple sensors per car, or something to direct the sound, like a cone, but I’m not sure how that would go. you could also rotate, but the wiring and timings would be tricky

Another option would be an analog light sensor, again you have a directionality problem, but with lights on each car, it would be brighter the closer another car is.


Another option that might work. If you put a Raspberry Pi Pico W on each car. Set that as an access point, then detect the signal strengths of the other cars.


  1. I don’t think the Pico W can be an access point and scan for other networks
  2. I don’t know how long a scan takes
  3. I don’t know how sensitive the signal strength is

You could potentially solve the first by having 2 pico W on each car, one to broadcast, the other to scan… you could experiment a bit with 2 and see how you go

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