What is Pulsar?
Pulsar is a free, open-source, browser-based logic analyzer designed for the Cypress EZ-USB FX2LP (fx2lafw). It enables hardware engineers, embedded developers, and hobbyists to capture and analyze digital signals directly in a web browser using WebUSB — with zero installation, no native drivers, and no proprietary software.
Supported Hardware
Pulsar works with Cypress EZ-USB FX2LP-based logic analyzers, including popular clones compatible with Sigrok's fx2lafw firmware (USB VID:PID 04B4:8613, 04B4:0053, 1D50:608C). These affordable USB logic analyzers are widely available and provide 8 digital channels with configurable sample rates from 100 kHz to 24 MHz.
Key Features
- WebUSB connectivity: works in Chrome, Edge, and all Chromium-based browsers without drivers
- 8-channel digital signal capture at sample rates from 100 kHz to 24 MHz
- Automatic firmware upload to the FX2LP via its USB bootloader
- Interactive waveform viewer with smooth pan, zoom, fit-to-screen, and time measurement cursors
- Built-in protocol decoders: UART (serial), SPI (Serial Peripheral Interface), 1-Wire, and DHT11 temperature/humidity sensor
- Drag-and-drop channel and decoder row reordering
- Signal selection, cropping, and export
- Full compatibility with Sigrok .sr capture files for import and export
- Runs entirely in the browser — your data never leaves your machine
Use Cases
Pulsar is ideal for debugging embedded systems, reverse-engineering serial protocols, verifying SPI and UART communication, analyzing sensor data lines (DHT11, 1-Wire devices), teaching digital electronics, and quick signal checks without launching a full desktop application. It is a lightweight alternative to PulseView and other Sigrok frontends.
Technology
Built with vanilla JavaScript (ES modules), Web Workers for background computation, Canvas API for high-performance waveform rendering, and Vite for bundling. No frameworks, no runtime dependencies.