In recent years, there has been an increase in the number of nonlinear loads connected to the electrical system due to the use of semiconductors in various industrial and civil applications. The increased use of nonlinear loads in modern electrical power systems, in addition to the advantages they have brought to various applications, has significantly increased the high-order harmonics in both voltage and current magnitudes, negatively affecting the performance of electrical equipment and the quality of the supplied power. To address this problem, in this paper we have proposed a real-time monitoring system for high-order harmonics in voltage or current magnitudes, based on an ARM Cortex-M0 microcontroller integrated on the PSoC4 CY8C4245AXI-483 platform. The monitoring system uses a base-2 FFT (Fast Fourier Transform) algorithm for spectral analysis of voltage and current signals, in accordance with the IEC 61000-4-7 standard. The measurement platform performs high-resolution signal processing by sampling at a frequency of 1600 Hz and uses the Hamming function to estimate with considerable accuracy the frequency spectrum of the voltage and current magnitude. The calculation of the effective value and Total Harmonic Distortion (THD) is performed up to the 15th order of harmonics, enabling the identification of deviations from the ideal sinusoidal shape. The proposed monitoring system has been tested in laboratory conditions, where comparisons with standard measuring devices (FLUKE 77III) have shown a measurement inaccuracy of less than ±5%. In laboratory conditions, different signal shapes (sinusoidal, quadratic and triangular) have been analyzed, proving the flexibility and reliability of the system under different operating conditions. Experimental results show that this system offers a low-cost, high-performance solution for power quality monitoring applications in low-voltage networks, meeting the requirements for class I measurements according to the international standard IEC 61000-4-7.