An electronic valve timing control unit has been developed mainly for the internal combustion engine operation. This study aims to implement a similar technology into a single-piston expander (SPE) with readily available and low-cost microcontrollers. The study used an Arduino Mega 2560 and ESP32-WROOM microcontrollers to control the valve timing with the rotational input signal obtained from an absolute encoder. The SPE has been expected to run at the rotational speed of up to 2000 rpm. This setup was prepared to simulate the actual SPE operation using a direct current motor to drive the spindle connected to the encoder shaft to create a similar hardware testing and controlled environment. The study aims to identify the efficiency of the microcontroller’s performance with a variation of the valve’s opening and closing time. Results have shown that the clock rate of the microcontroller affects the performance of valve timing response. By increasing the clock rate, the microcontroller can control the valve at a higher speed.