I need two Arduino units with the HC-06 Bluetooth board to communicate with each other and one of these Arduino units also connected to my Android phone. Is this possible to do with just two HC-06 modules, or even three? Or is there a better solution for this?

To reiterate what is going on here: I have two Arduinos that are running off battery. Arduino 1 is sending data every 0.5 seconds to the Arduino 2. Arduino 2 collects this, adds its own bit of data to it, and then sends this new data packet to my Android phone which will only be connected to Arduino 2.

I haven't completely decided upon what kind of Arduino board to get, but it needs to be fairly small, but I am planning on the Adafruit Pro-Trinket 5v.

Hopefully you get the basic scenario, let me know if you need more clarification and what you think could be done here.

Thanks a lot!

  • Just a thought: If you store data in Bluetooth advertising data, you won't need to do anything fancy with Arduino 2. Have Arduino 1 update its advertising data as often as you want. Have Arduino 2 scan and get the data stored in Arduino 1's advertising data. Then, Arduino 2 can update its own advertising data with the updated data. Scanning and getting Arduino 2's data from Android is do-able. I didn't add this as an answer because I don't know if the HC-06 supports bluetooth scanning (it probably does).
    – krol
    Nov 29 '16 at 14:04
  • Why Bluetooth? Why not WiFi? Having direct experience with both, WiFi (nodeMCU) is 100% reliable, simpler (not need to "pair" anything) and versatil (HTTP, MQTT or whatever protocol you like) and you can have multiple connections simultaneously. Bluetooth, is a little PITA.
    – user31481
    Jul 29 '17 at 9:38

Should be possible, but only if you setup the Bluetooth module of Arduino 2 as the master. You see, Bluetooth requires to connect to a master. A master can connect to 8 slaves in total. Because Arduino 2 connects to multiple devices (Arduino 1 and your Android device) it should be the master. This also means your Android device cannot connect to any other devices.

Hope this gives you a place to start exploring.



So From Whatever I can Understand you could do this.

  1. make one of the boards talk to a master control board.
  2. make the control board talk to your phone.

Why don't you change your approach

  1. Make the board A communicate with board B with Bluetooth.
  2. Use different pins to setup communication b/w phone and board b.

Arduino to Arduino Bluetooth- http://www.martyncurrey.com/arduino-to-arduino-by-bluetooth/

Arduino to phone via Bluetooth- http://www.instructables.com/id/Connect-Arduino-Uno-to-Android-via-Bluetooth/


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