Abstract: The purpose in this study is constructing digital filter with application of modern microprocessor systems, learning methods of automatic projecting and perfecting skills of programming in language of assembler. In this study, the microprocessor of firm MICROCHIP PIC16C711 is used which has possibilities of analog signal’s processing. DAC is not a part of the microcontroller and it is carried out separately, its entrances are connected to port B. The program written in language of assembler is universal for all microcontrollers of MICROCHIP having a possibility for analog signal’s processing. It is necessary to configure ports and to consider specification GPR (General Purpose Register) and special registers according to the documentation on demanded model.