STM32-Based Digital Oscilloscope
Mixed-Signal Instrumentation & Hardware Design
Status:Completed
Description
This project is a fully featured STM32-based digital oscilloscope and multi-instrument measurement platform inspired by the original EMBO (Embedded Oscilloscope) project. The design expands upon the reference implementation with custom hardware, additional protection, improved signal conditioning, and a dual-firmware architecture to improve usability and accessibility.
Project Overview
The oscilloscope is built around an STM32F303RE and provides multiple measurement instruments including a multi-channel oscilloscope, logic analyzer, signal generator, voltmeter, counter, and PWM generator. A major design focus was creating robust analog front-end circuitry capable of handling wide voltage ranges while maintaining signal integrity.
The hardware was designed as a custom PCB with BNC inputs, AC/DC coupling, configurable voltage ranges, overvoltage protection, and careful attention to PCB layout practices for mixed-signal performance. In addition to the hardware, the project includes firmware modifications and a custom USB-based workflow that simplifies software installation for the end user.
Hardware Features & Capabilities
- 4-channel oscilloscope up to 3.2 MSps (5 MSps max, limited by stability)
- 44k samples (8-bit) or 22k samples (12-bit)
- 1 MΩ input impedance with ~12 pF input capacitance
- BNC inputs compatible with standard oscilloscope probes
- AC or DC coupling selectable via hardware switch
- Configurable input voltage range (default ±3.3 V)
- Overvoltage and undervoltage protection on inputs
- Dual-channel signal generator up to 4.5 MHz
- Logic analyzer (14.4 MSps), voltmeter, counter, and PWM generator
Design Challenges & Debugging
- Designing an analog front end capable of wide voltage ranges with low noise
- Implementing a resistor-capacitive divider to compensate for parasitic capacitance
- Managing op-amp stability when driving capacitive STM32 ADC inputs
- Identifying ringing issues and resolving them with series output resistors
- Ensuring proper PCB return paths and reference planes for high-speed signals
- Tuning capacitor values experimentally to match divider gain
Design Walkthrough & Engineering Decisions
In this video, I walk through the hardware design, schematic decisions, PCB layout considerations, debugging process, and firmware architecture. The discussion focuses on real-world challenges such as parasitic effects, signal integrity, and firmware patching techniques.
Project Resources
GitHub Repository →Hardware Design & Assembly Gallery
