project: android app for Samsung mobile phone, for remote bluetooth control of 8 leds digital outputs of microcontroller Bolt 18F2550.

Author: Angelica Viridiana Rebolloza Gonzalez


Figure 1: Android App for remote control of Bolt 18F2550 system. Pulse icon 'LedContro'

Figure 2: Devices you need to make tests of project.


Since the appearance and the current low cost of smartphones, now there is a new and simple tool for remote control and information management with microcontrollers systems, via Bluetooth links.

Additionally, these new mobile phones already have their own operating system, making it possible for R&D engineers to implement numerous software applications oriented to this objective.

In this project, a software for mobile phones with Android operating system, which allows the user to remote controlling 8 digital outputs of the Bolt 18F2550 system, equipped with a Bluetooth HC-06 with serial port module was developed.

Furthermore, the Bolt card has 8 leds, which allow the user to observe the status of its outputs. These eight outputs are available in the corresponding J5 connector, so that the user can insert an expansion circuit, for example, 8 relays, which in turn may activate devices such as lamps, motors, or valves (see Figure 2 ).


The application file is provided below on this page (LedControl.apk file). You may transfer it from your PC to your mobile phone, either through a compatible USB cable, or via a Bluetooth link.

On your mobile, do not forget to turn on the option that allows the execution of programs with a source other than Google Play. To do this, click the icon 'Settings' and then 'Security', and enable the option as shown in the image:




When you pulse on the application icon, a menu like the one shown above appears. Pulse on 'Only once' to install the program. Once installed on your mobile, you will see an icon named 'LedContro' (see Figure 1).

Once the Android mobile application is opened, it offers a user-friendly display, through which you can enable or disable any of the 8 outputs of Bolt card by clicking the appropriate icon for each of the 8 leds (Led0. .. Led7). See Figure 2.

The same screen also displays a special icon to set the Bluetooth link with Bolt card. Remember that the Bluetooth link requires prior settings on your mobile phone.

The program also receives confirmation from Bolt 18F2550 system of the status of leds, so that the corresponding icon will show a red color if the LED is off and green when the LED is on. Thus, it is not essential that the user has a direct observation of the controlled devices.


For the Android application to work properly, it is necessary that the Bolt 18F2550 system, is loaded with the corresponding .hex (leds.hex file), which is provided below on this page. The firmware is a simple program written in ANSI C, which receives commands from the mobile and activates or disables the corresponding output.

If the user wants to modify some of the functions of the firmware, the complete project for MPLAB IDE and C18 compiler is provided.


The communication between the mobile phone and card Bolt is set via a Bluetooth link, Class 2, with a range of 10 meters. The Bolt card must have its Bluetooth Module HC-06 with serial port attached to its DB9 connector.

It is also also necessary to previously configure the Bluetooth options of mobile to make communication possible.


All files you will need:


Transfer the app LedControl.apk to mobile phone.

Load firmware file leds.hex to Bolt 18F2550 system.