The program in C language controls the system. The Raspberry Pi works under the Linux operating system. In this situation, the serial interface is used to service the terminal by default. It was necessary to make some modifications in configuration files to use UART resources and the serial interface for oscilloscope control. Additional C language libraries for SPI and UART, specially dedicated for BMC2835 could be used (WiringPi , BMC2835 libraries). For example, in our tested program, the BMC2835 library for SPI interface control was used. The Raspberry Pi module works under an Open Source operating system Linux (Raspbian). Therefore, also C program was written in a free programming environment (Geeny editor) and for data visualization, the free Gnuplot and Scilab environments were used. The main C language program has the following functions: SPI interface initialization, UART RxD and TxD lines initialization, sensor addressing in the array, frequency measurement, data presentation on terminal console, data saving in Gnuplot and Scilab acceptable format files, calling Gnuplot for data visualization in 2D and 3D plots. The program can also collect data in appointed time periods and create graphical files. Next, those files are used to produce animated movies to illustrate how the measured value changed in time. The Raspberry Pi does not come with a real-time clock, so the OS must use a network time server, or ask the user for time information at boot time to get access to time and date for file time stamping.