A handheld oscilloscope built on the ESP32, providing low-cost real-time visualization of low-frequency signals.
The Low-Cost Oscilloscope (LCO) is a compact handheld device designed to provide real-time visualization of low-frequency electrical signals using affordable, widely available components. At the core of the system is the ESP32-S3 microcontroller, which performs ADC sampling, signal processing, and display control. A dedicated analog front-end with attenuation, AC coupling, mid-rail biasing, buffering, and over-voltage protection allows safe measurement of signals up to ±16 Vpp. The processed waveform is shown on a 0.96” OLED display, and user interaction is provided through four tactile buttons for scaling and navigation. A custom four-layer PCB integrates the ESP32-S3, power management circuitry, display, and input stage into a compact 45׳70 mm form factor. Testing demonstrated stable sampling rates of approximately 25 kHz, enabling clear visualization of sine, square, and ramp signals. The project demonstrates that essential oscilloscope functionality can be achieved at low cost while maintaining portability, simplicity, and educational value.
Beyond meeting its functional goals, the project provided meaningful experience in PCB design, embedded firmware development, and practical debugging. The process included resolving hardware issues such as an inverted display pinout, adapting the input stage to real-world signal conditions, and rewriting the firmware to match the ESP32-S3 architecture. These challenges contributed to a deeper understanding of ADC behavior, signal conditioning, and real-time embedded systems. The final device demonstrates not only technical feasibility but also the importance of iterative design, testing, and careful integration when developing compact hardware-based projects.
