Arduino Bluetooth Controller Using an Old Cell Phone

A cell phone works quite well as as an Arduino robotic vehicle controller. It communicates using Bluetooth with an HC-05 or HC-06 Bluetooth module that is connected to the Arduino. There are numerous free Arduino Bluetooth controller apps for Android phones, but more students these days have Iphones. Several old Samsung Galaxy S4 phones were purchased on ebay for around $10 and repurposed as dedicated controllers that students can use to control their Arduino-powered vehicles.

Arduino Uno

9V Battery Pack

HC-06 Bluetooth Module

Samsung Galaxy S4 or similar old Android cell phone

Older cell phones (like the Galaxy S4) may not work with Google Play Store. To get around this, you will need to use an Android Package Kit (APK) downloader site such as uptodown. Open it up and search for "Arduino Bluetooth Controller." Choose one that looks good, such as Arduino Bluetooth Control by Giristudio. Download the APK file to your computer.

Go to your cell phone and open “Settings“.and select “Apps“.

Select “Menu” at the upper-right corner, then choose “Special access“.and select “Install unknown apps“. If this does not work, then go to Security and check Unknown Sources.

Select “My Files“, then toggle the “Allow from this source” option to “On“.

Next, connect your cell phone to your computer with a USB cable. Your cell phone will show up as an external drive. Find the downloaded APK file and drag it to the Downloads folder on your phone. Once it has been moved to your phone, click on it to begin the installation and follow the instructions on the screen.

1. Connect 5V to 5V, GND to GND, RXD to Pin 0, TXD to Pin 1
2. Connect the USB cable from the Arduino to the computer
3. Open up Arduino IDE and upload a blank sketch
4. Open up Serial Monitor on the computer
5. Type AT and the monitor should display OK
6. TYPE AT+NAMEnewname with no space between NAME and newname
7. Type AT+PINnewpin with no space between PIN and newpin
8. Open up the Bluetooth settings on your phone and pair it with the HC-06
9. Open up the Bluetooth controller app and verify that it connects to the HC-06

Next, connect the HC-06 to any two pins (except 0 and 1) that can be configured for software serial in an Arduino sketch. Write or download a simple sketch that simply displays the character that is sent from the cell phone controller and received by the Arduino.

Turn on the power to the Arduino and the cell phone. On your phone, go to Settings and Bluetooth, and pair with your HC-06. Open up the controller app, select the gamepad option - it should connect automatically. You will then need to open up the controller settings and type in the appropriate character to use for each button. With the Arduino connected to your computer, open up the Arduino IDE and the Serial Monitor. When you press a button on the controller, you should see that character appear on the serial monitor. Congratuations, you did it!