DIY-ECG on Arduino UNO Q

Arduino App Lab

Arduino UNO Q

<html><body>For quite some time I have been developing a simple DIY ECG amplifier board that can be soldered and built by anyone with basic electronics skills. The amplified ECG signal is digitized by an Arduino and transmitted to a computer, where it is digitally filtered and visualized. The DIY ECG front-end amplifier board is available here: <a href="https://github.com/diy-ecg/diy-ecg-pcb-uno">https://github.com/diy-ecg/diy-ecg-pcb-uno </a>The board is designed as a simple, easy-to-solder ECG amplifier suitable for educational and experimental use. It is built around a Quad-OpAmp like MCP6004. <figure><img src="https://projects.arduinocontent.cc/e39afdc1-3973-439e-895e-db15d31b09d1.jpg"/><figcaption>PCB Kit for ECG-Amplifier</figcaption></figure>One long-term goal of this project has always been to eliminate the need for an external PC. With the new Arduino UNO Q, this finally becomes possible. The Arduino UNO Q combines a real-time microcontroller (MCU) with a Linux-capable microprocessor (MPU) on a single board. The MCU performs deterministic ADC sampling, while the MPU runs Debian Linux and handles signal processing, networking, and a modern web interface. The ECG signal can be viewed in any web browser on the local network – or directly on the UNO Q itself when running in SBC mode. The complete firmware, Linux backend and WebUI are available here: <a href="https://github.com/diy-ecg/diy-ecg-uno-Q">https://github.com/diy-ecg/diy-ecg-uno-Q </a>System Architecture The solution is built as a clean end-to-end pipeline consisting of three main parts: ECG Amplifier → MCU (ADC) → UNO Q RPC Bridge → Linux Python → WebSocket → Browser UI 1) MCU Firmware (STM32U585) File: sketch/sketch.ino The MCU handles all real-time tasks: •	Samples the ECG signal at 200 Hz •	Stores samples in a ring buffer •	Packages data into compact binary frames •	Exposes frames via the UNO Q Bridge/RPC interface The Linux side fetches data using the RPC call: ecg_get_frame() Each frame contains: •	Absolute start timestamp (t0) •	Per-sample timestamp deltas •	Compact binary encoding •	CRC checksum This keeps bandwidth low while preserving precise timing. 2) Linux Python Backend (UNO Q Debian) Entry point: python/main.py Data pipeline: python/data_stream.py RPC transport: python/arduino_q_bridge_rpc.py The Linux MPU performs all higher-level processing: •	Pulls frames from the MCU via RPC •	Maintains a circular buffer •	Applies digital filters (notch, high-pass, low-pass) •	Detects R-peaks •	Computes heart rate (BPM) The backend streams live data to the browser via WebSockets using three message types: Message	Purpose ecg_frame	Full buffer for new clients ecg_delta	Incremental real-time updates ecg_meta	Status, BPM, filter settings, sampling rate 3) Browser WebUI Files: •	python/webui/index.html •	python/webui/app.js •	python/webui/styles.css The WebUI runs in any modern browser and provides: •	Real-time ECG plotting •	BPM display •	Filter status panel •	Continuous updates without page refresh Rendering is done using WebGL (webgl-plot) for smooth high-performance plotting. Data Flow Summary 1.	MCU samples ECG at 200 Hz 2.	Frames are fetched via RPC (ecg_get_frame) 3.	Python backend filters and analyzes the signal 4.	WebSocket server streams live data 5.	Browser visualizes ECG in real time <figure><img src="https://projects.arduinocontent.cc/8c7272c7-4613-4544-80a6-c6e83e8812f2.jpg"/><figcaption>Arduino UNO Q connected to a MacBook via USB. The ECG signal is visualized in real time using a web browser.</figcaption></figure>Everything runs directly on the Arduino UNO Q. Standalone Operation in SBC Mode When running in SBC mode, the Arduino UNO Q operates as a full Linux single-board computer. In this configuration, I use a Raspberry Pi 15.6" portable monitor powered via USB-C. Both the Arduino UNO Q and the monitor are powered from a single powerbank (e.g. UGREEN Nexode Power Bank 145W) This setup provides: •	Fully portable operation •	No connection to mains power •	Reduced electrical noise •	Improved patient safety through battery operation The entire ECG system becomes a self-contained workstation: ECG Amplifier → Arduino UNO Q → Linux DSP → WebUI → 15.6" Monitor <figure><img src="https://projects.arduinocontent.cc/08ec9f06-effd-426f-a658-745667e0b069.jpg"/><figcaption>Standalone operation in SBC mode: the web browser runs directly on the Arduino UNO Q. Both the Arduino and the monitor are powered from a power bank (left).</figcaption></figure>Running the System Start firmware and backend using the Arduino App CLI: arduino-app-cli app start . Open the Web UI in a browser: Local on the UNO Q: <a href="http://localhost:7000">http://localhost:7000 </a>With port forwarding: <a href="http://127.0.0.1:7000">http://127.0.0.1:7000 </a>RemarkIf you are interested in the project hardware: I occasionally have PCBs, ECG cables, electrodes, and related components available. Feel free to contact me at:<a href="info@diy-ecg.org">info@diy-ecg.org</a> </body></html>

DIY-ECG on Arduino UNO Q

Standalone ECG acquisition, processing and Web visualization using MCU + Linux MPU