To address the problems of complex circuitry, high cost, and difficult debugging in conventional electrochemical etching control systems for tungsten tips used in scanning tunneling microscopy (STM), this study develops a simple microcontroller-based tungsten probe preparation device. The device uses a microcontroller as the core control unit to acquire the etching-current signal in real time and identify its abrupt variation. Once the tip is formed, the system automatically cuts off the etching circuit and simultaneously drives the mechanical actuator to retract the probe from the electrolyte. Experimental results show that the fabricated tungsten probes have a tip radius of curvature of approximately 50 nm and exhibit uniform, regular morphology. Atomic-resolution images of graphite were successfully obtained in STM imaging tests, demonstrating the effectiveness of the prepared probes. The device is easy to operate and highly practical, providing a feasible solution for laboratories to fabricate high-performance nanoscale sharp probes.