Frequently Asked Questions¶
General Questions¶
What is OpenTraceLab?¶
OpenTraceLab is an open-source ecosystem for logic analysis, consisting of three main components: - OpenTraceCapture - Hardware abstraction and signal acquisition - OpenTraceView - Graphical interface for signal visualization - OpenTraceDecode - Protocol decoders for signal interpretation
How is OpenTraceLab different from sigrok?¶
OpenTraceLab is a fork of the sigrok project with modernized architecture, enhanced features, and active development focused on logic analysis applications.
What hardware does OpenTraceLab support?¶
OpenTraceLab supports 200+ devices including: - FX2-based logic analyzers (~$10) - Saleae Logic series - Rigol oscilloscopes - Various multimeters, power supplies, and function generators
Installation Issues¶
"Cannot access USB device" error¶
Linux: Install udev rules and add user to plugdev group:
sudo cp contrib/60-opentracelab.rules /etc/udev/rules.d/
sudo usermod -a -G plugdev $USER
"Library not found" errors¶
# Linux - update library cache
sudo ldconfig
# Or set library path
export LD_LIBRARY_PATH=/usr/local/lib:$LD_LIBRARY_PATH
Python decoder errors¶
Ensure Python development packages are installed:
sudo apt install python3-dev python3-setuptools python3-numpy
Usage Questions¶
How do I capture my first signal?¶
- Connect your logic analyzer via USB
- Launch OpenTraceView
- Configure channels and sample rate
- Connect probes to your circuit
- Click "Run" to start capture See our capture guide for details.
Which logic analyzer should I buy?¶
For beginners, we recommend: - FX2-based analyzers - Cheap (~$10), 8-16 channels, 24MHz - Saleae Logic 8 - Professional quality, excellent software - OpenBench LogicSniffer - Open hardware design
How do I decode protocols?¶
- Capture your signal in OpenTraceView
- Go to Decoders menu
- Select your protocol (I²C, SPI, UART, etc.)
- Configure channel mappings
- View decoded results
Can I write custom decoders?¶
Yes! OpenTraceDecode uses Python for protocol decoders. See our decoder development guide.
Hardware Questions¶
What sample rate do I need?¶
- I²C/SPI: 4-10x the clock frequency
- UART: 10x the baud rate minimum
- High-speed protocols: Use fastest available rate
How many channels do I need?¶
- Basic protocols: 2-4 channels (I²C, SPI, UART)
- Parallel buses: 8-16 channels
- Complex systems: 16+ channels recommended
What about probe quality?¶
Good probes are essential: - Use short ground leads (<3cm) - Quality probe hooks (E-Z-Hook XKM series) - Proper impedance matching for high-speed signals
Software Questions¶
Can I use OpenTraceLab with other tools?¶
Yes! OpenTraceLab can: - Export data to CSV, JSON, VCD formats - Integrate with scripts via OpenTraceCLI - Work with collectd for monitoring - Interface with custom applications via API
Does OpenTraceLab run on my OS?¶
OpenTraceLab supports: - Linux - Native packages and AppImage - Windows - Installer and portable versions - macOS - Homebrew and .dmg packages - FreeBSD/NetBSD/OpenBSD - Source builds
How do I get help?¶
- Documentation - This website and manuals
- GitHub Issues - Bug reports and feature requests
- Community - Discussions and forums
- Email - Direct support for complex issues
Performance Questions¶
OpenTraceView is slow with large captures¶
- Use "Fast" rendering mode for large datasets
- Reduce visible time range when zoomed out
- Consider using OpenTraceCLI for batch processing
- Increase system RAM for better performance
My device isn't detected¶
- Check USB connection and cables
- Verify device is supported
- Install proper drivers/udev rules
- Try different USB ports
- Check device power requirements
Capture keeps stopping¶
- Check USB cable quality
- Reduce sample rate if bandwidth limited
- Verify trigger settings
- Check available disk space
- Monitor system resources
Protocol-Specific Questions¶
I²C decoding shows errors¶
- Verify SCL/SDA channel assignments
- Check pull-up resistors on I²C lines
- Ensure adequate sample rate (>4x I²C clock)
- Verify signal voltage levels
UART data looks garbled¶
- Confirm baud rate setting
- Check data bits, parity, stop bits
- Verify signal polarity (inverted?)
- Ensure stable clock reference
SPI decoding is incorrect¶
- Verify MOSI/MISO/CLK/CS assignments
- Check SPI mode (CPOL/CPHA settings)
- Confirm bit order (MSB/LSB first)
- Verify chip select polarity
Troubleshooting¶
General debugging steps¶
- Check all connections
- Verify power and ground
- Confirm signal voltage levels
- Test with known-good signals
- Try different sample rates
- Check for electrical noise
Getting more help¶
If you can't find answers here: 1. Search existing GitHub issues 2. Create detailed bug report with: - OpenTraceLab version - Operating system - Hardware details - Steps to reproduce - Sample capture files 3. Use the "Report Issue" button on any documentation page