Due to the rapid development and diffuse use of a multitude of technologies in the concept of the Internet of Things, we have prepared several development boards for the practical introduction of students to the concept of the Internet of Things (hereinafter referred to as IoT), through which students become acquainted with the real problems in the design of IoT networks and communication protocols used in connecting IoT devices. In the initial phase, due to the speeding up of development, we have prepared three devices that use the same physical layer, which is not typically used in IoT networks, that is, wireless WiFi. The development boards are designed to develop software that optimizes the communication protocols of the higher layers, especially application layer protocols, and to show how individual protocols work in concrete cases, so this decision does not pose a major problem in the initial phase.

Many projects, especially in the pedagogical sphere, use to demonstrate and study the performance of IoT protocols on the application layer, such as MQTT and CoAP, high-power devices, which may lose the essence of the IoT concept and protocols, which are often optimized precisely for performance at less powerful , battery powered devices. In the concept of IoT, less powerful devices that do not have “unlimited” processing capacity come to the fore, and special attention should be paid to the implementation or development of the software. Whether it is attention to regulating power consumption or choosing protocols appropriately based on processing capabilities, especially at the higher layers of the IoT protocol stack.

 

The most powerful IoT node has largest dimensions, while offering the highest processing capacity. The primary task of the development plate is to control the stepper motors for the blinds through a specially designed clutch. The board includes three drivers for stepper motors, a WiFi module, an air quality sensor, and a temperature and humidity sensor. Some LEDs and a 32.768kHz crystal have been added to ensure the correct clock speed of the RTC register in the STM32L152 microcontroller. The selected microcontroller is of low energy type and should be suitable for battery powered devices. Programming of the microcontroller is performed via USB bus in DFU mode, but also via SWD JTAG. The same USB bus can be used to debug a program or interact with a device via a PC. Due to its design and high processing capacity, this board offers the most flexibility in using different protocols. In the first phase, the board offers two different communication interfaces (USB and or WiFi). In a rapidly evolving IoT world, the ability to change the protocols used at individual levels of the IoT protocol stack is crucial. Due to its high processing capacity, the board enables the TCP and UDP transport layer to be independently modified. On the application layer, we can implement both currently most used protocols of this layer in IoT, that is, MQTT and CoAP, and we can also experiment with the HTTPS protocol. The tile also allows us to implement the LwM2M intercommunication protocol implemented over the CoAP protocol using the CoAP protocol. In the first phase, the tile is equipped with a WiFi physical connection, which we intend to upgrade in the second phase with a BLE connection, which would bring flexibility and the ability to test both network layer and physical layer protocols.

The smaller development boards for IoT node are equipped with a WiFi module, which is also a microcontroller. The development board is less processor efficient than the DPSLAB SUN board and is suitable for implementation in battery-powered IoT sensor nodes. The other peripherals on the plate are just the temperature sensor on the MARS plate and the IR transceiver on the MOON plate and the housing for two AAA batteries. The task of the MARS sensor node is to send data from one sensor at specified intervals to the IoT network. In more specific cases, however, the node can perform the task of the IR controller, which is done by the MOON board.