USB Cable Types
Edit on GitHubHow to tell a data cable from a charge-only cable, and which cables work for flashing, serial and bridge use.
USB Cable Types
Most “my beacon won’t connect” reports end with a charge-only cable. This page is the quick guide to picking the right one.
Data vs charge-only
- Data cable: all four wires (power + D+/D-). Works for flashing, serial, and the bridge.
- Charge-only cable: two wires (power only). Charges fine, never appears as a serial port.
There is no reliable way to tell them apart by look. Test: plug the cable between the beacon and a computer and check whether a COM port appears (see Serial Port Detection).
What the beacon needs
| Task | Cable |
|---|---|
| Flashing | Data, short (under 1 m preferred) |
| Serial monitor / bridge | Data; length is less critical once uploaded |
| Bench power | Either, if you also have a data cable for serial |
Common pitfalls
- Braided “premium” cables are often charge-only because they are sold as chargers.
- Micro-USB connectors wear out. If a board worked and now fails intermittently, replace the cable first.
- Extension cables and adapters add resistance and can drop bytes during uploads. Plug the beacon directly into the machine when flashing.
Quick test without a computer
If you only have a phone charger, you cannot verify the data lines. If you have a laptop, plug in and run:
# Windows (PowerShell)
Get-CimInstance Win32_SerialPort | Select-Object DeviceID, Description
# macOS
ls /dev/cu.usb*
# Linux
ls /dev/ttyUSB* /dev/ttyACM* 2>/dev/nullA new port appearing while the beacon is plugged in means the cable carries data.