Understanding USB-C UART Debugging
Learn how UART debugging works with USB-C devices and how LumeLink makes the process simpler and more reliable.
UART Over USB-C
USB-C is more than just a connection standard; it's a versatile interface that supports multiple protocols simultaneously. Among its many uses, USB-C can carry UART signals through special pins called SBU1 and SBU2 (Sideband Use).
In modern USB-C devices, these SBU pins are often used for:
- Debug Interfaces: Outputting boot logs and debug information
- Development Access: Providing shell access during development
- Firmware Updates: Alternative update channels when normal methods fail
Despite USB-C's complexity, the UART protocol remains simple and reliable, making it ideal for debugging even in complex modern devices.
How USB-C UART Debugging Works
USB-C introduces some unique considerations for UART debugging:
- UART signals travel through the SBU1 and SBU2 pins in the USB-C connector
- These pins are separate from the main USB data lines
- Special hardware is needed to access and convert these signals
- Cable quality matters – not all USB-C cables include the SBU pins
The Challenge with USB-C
While USB-C offers many advantages, accessing UART data from these devices presents unique challenges. The compact connectors are fragile, and connecting to the right pins requires specialized hardware. This is precisely the problem LumeLink was designed to solve.
Common USB-C Debug Scenarios
Development Boards
Many modern development boards with USB-C ports route debug UART through SBU pins, allowing for a cleaner design with fewer connectors.
Consumer Electronics
USB-C devices often include hidden UART interfaces for factory testing and diagnostics, accessible through the SBU pins.
The LumeLink Solution
LumeLink was specifically designed to tackle the challenges of USB-C UART debugging by:
SBU Pin Access
LumeLink specifically targets the SBU1 and SBU2 pins within the USB-C connection, extracting UART data without interfering with normal USB operation.
Pass-Through Design
The device features a complete pass-through port, allowing your device to function normally while simultaneously capturing debug data from the UART port.
Female Port Protection
Using all female ports means that only replaceable cables are at risk of damage, protecting your investment and ensuring long-term reliability.
FT232RL Reliability
Built around the industry-standard FT232RL chip, LumeLink ensures broad compatibility and reliable operation across all major operating systems.
Using LumeLink
- 1 Connect your computer to the appropriate port on Side A using a USB-C cable
- 2 If needed, use the pass-through port on Side A for power or data
- 3 Connect your USB-C device to the port on Side B (must use a 16-pin+ cable)
- 4 Use your terminal application to view UART data
Technical Details
- UART Pins: SBU1 (TX), SBU2 (RX)
- Compatibility: Any USB-C device using SBU pins for UART
- Cable Requirement: 16-pin or higher USB-C cable
Start Debugging Today
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