Bluetooth SMD Module RN-42 Project

Hey guys,
I am extremely new to Arduino programming and its use in general as well as new to circuitry. But, basically I am working on a relatively straightforward project where I am using the RN-42 chip to communicate with an android phone (i've designed an app). Basically, if you lose your phone I want to be able to press a button which will send a signal to the app and which will then trigger a notification on your phone. My question here is basically where I should start with the Arduino/if I need a microcontroller. I don't know how to set up the RN-42 with the Arduino in the slightest and any help would be greatly appreciated.
Please don't hesitate to ask questions or give any recommendations at all.


Can you provide a link to the particular RN42 module you're using?


I apologize for the delayed response! This is the module we are using: Bluetooth SMD Module - RN-42 (v6.15) - WRL-12574 - SparkFun Electronics. We have figured out how to deliver a power supply to the module using an Arduino Uno with some relatively simple soldering. I am, however, quite confused with how to send a signal from the module to the application that we are developing for Android. For example, if someone were to press a button that were hard wired to the Arduino, how could I have that button press result in a specific signal being sent to the phone? Thanks again for the reply!


The bluetooth module is a serial device. Presuming you connect it to the Arduino’s hardware RX/TX pins (bluetooth TX-Arduino RX & RX-TX) you can transmit data from the Arduino out the bluetooth module using standard Serial library commands like write, print & println. If you use IO pins other than D0 & D1 then you’d use software serial, and those related commands will do the job.

There’s a fair bit of info about if you google the topic. I see this youtube video by Kevin Darrah talks through the various IO connections on that RN-42 module when he used it to setup a standalone Arduino for programming over bluetooth.

Note that module uses 3.3V logic so you’ll need to make sure you have some translation circuitry in the middle so your 5V Arduino doesn’t harm it.

Cheers ! Geoff