**4. Arduino pro mini – Microcontroller**

Arduino Pro Mini is used in the system for application module. It does not have inherent programmer since it is an application module. Various connectors and USB port are useless and they are removed from the module because the module is connected with the application programmer. There are two versions of Arduino Pro Mini. They are classified based on the working voltage of controller. The voltage levels are +3.3 V and + 5 V. Based on the application, the designer can choose the appropriate board.

In recent years, Arduino boards are commonly used because its operation and architecture is easy to understand. Also the original module schematics and required software modules related to Arduino is available as an open source platform. Based on the requirement designer can customize the system using this open source platform. Different types of Arduino boards are available on the market for designing a system [7]. They are accessible with various packages and features. Appropriate boards can be chosen depending on the requirement.

The few reasons why pro mini is selected over other are listed below:

Case1: Permanent installation of the system is used. Only the board is required to be programmed once in permanent applications. In such systems, the features like a USB programmer, I/O connectors and other supporting hardware is not required. The pro mini is explicitly designed for those systems which uses permanent installation. It has some basic hardware modules that is just enough for those applications.

Case2: This pro mini board is one of the smallest boards of Arduino. Because of its small size it can be used in mobile applications.

Case3: The cost of the board is significantly lesser due to its basic hardware structure.

#### *IoT Applications Computing*

Case4: It can able to store most application programs in its 32Kbytes memory.

The operation of Pro Mini is similar to any other development board. All you have to do is to write the controller program and select the appropriate interfacing modules to get system running. The detailed step for the programming of pro mini is given below.


Remove the programmer module. Provide the power and connect the necessary peripherals. The desired output is obtained after resetting the control and executing the program.
