Master’s thesis contains description parameters of microcontroller ATMEGA644P, also contains differences between older and newer version of microcontrollers ATMEGA644 and ATMEGA644PA. Inside structure of microcontroller, memories and peripherals are described here. The construction of the universal microcontroller unit is main target of this thesis. The unit contains supply, A/D converter, current loop, communication interfaces, temperature sensor, accelerometer and other. The unit collects and saves data, communicates by interfaces and manages other functions. Using devices and circuits are described in this thesis. Development of software for microcontroller(firmware) are positioned to last part of this thesis. This software control functions of all parts positioned on the unit.