A variant of programming the microcontroller and modeling the system in the «Proteus» RTC (Real Time Clock) circuit, together with LED matrices, is proposed. The practical significance of the work is the study of the simplest logic circuits in the AVR assembler language, for instance, a shift register, a decoder, a LED matrix, a real-time clock circuit and a seven-bit indicator, both individually and in a full-fledged system. This work can be used for teaching students and for laboratory work in distance learning.