Software-related EMI behavior of embedded microcontroller

This paper studies software-related microcontroller's conducted electromagnetic interference (SW-cEMI) behaviors when microcontrollers are executing different programs of the same functionality. The SW-cEMI behaviors of different program types, clock sources, and programmable PLL settings are measured and observed. Two major trends of microcontrollers are used as devices under test. The result shows that 10-12 dB cEMI differences even on a simple LED blinking function implemented by different program types. To the best of our knowledge, this work is the first observation on EMI phenomena of software implementations on microcontroller's programs. Some advises are given to μC programmers for cEMI reduction.