Troubleshooting & Care
Flashing
| Problem | Fix |
|---|---|
| No serial port when the XIAO is plugged in | Use a USB-C data cable, not a charge-only one. Close other programs that use serial ports. |
| Install fails or the port disappears | Hold BOOT, tap RESET, release BOOT, then click Install again. |
| Board silent after flashing | Unplug and replug the USB once. |
| Flasher page has no Install button | Use desktop Chrome or Edge. |
Bluetooth connection
| Problem | Fix |
|---|---|
Octopus-16-XXXX not in the list | Check the power bank is on and the LED blinks slowly. Move closer. If the board was never flashed, see Firmware. |
Board shows another name (Octopos, FE-Gamepad-…, bioron_16) | It runs a different firmware build. Flash the official firmware again, or connect with a tool that finds it by service UUID. |
| Connects, then drops | Keep the board close to the computer, check the BLE antenna is clipped on, and retry. |
| No Bluetooth button in the browser | Use Chrome or Edge. Safari, Firefox and iPhone / iPad browsers don't support Web Bluetooth. |
| macOS: Python finds nothing | Allow your terminal to use Bluetooth: System Settings → Privacy & Security → Bluetooth. |
No data or bad data
| Problem | Fix |
|---|---|
| Connected, but no EEG data, or the LED fast double-blinks | The XIAO is mounted the wrong way round (180°). Reseat it so the 5V / GND / 3V3 labels line up. A board that flashes and shows up on Bluetooth does not prove the ADC is connected. |
| Gaps in the data | Lost packets. Check the sample counter, keep the board closer, and avoid crowded 2.4 GHz areas. |
| Values in the thousands of counts | That's raw ADC counts with an offset. Use µV (see Specification) and a band-pass filter. |
Signal
| Problem | Fix |
|---|---|
| EEG ok stays red | Press the board straight down so every pin touches the scalp. Part the hair under the pins. Sit still. |
| A few channels much noisier than the rest | Those pins aren't touching, or are stuck. Press more evenly, or check the pins (see below). |
| Huge swings in the signal | Blinks, jaw clenches or movement. Relax the face and keep still. |
| Alpha doesn't rise with eyes closed | Place the board over Pz or the back of the head. Keep the eyes closed for a full 10 seconds. |
| Strong 50/60 Hz hum | Something is on mains power. Use the power bank only, and keep away from chargers and power strips. |
Pogo pin care
The pogo pins have a spring inside. Over time, dirt, liquid or sideways force can make a pin stick (stay pushed in).
Why pins stick
- Dust, debris and hair inside the pin barrel
- Oils, moisture or sticky residue
- Sideways pressure, or pressing the board beyond the pins' travel
Keep them working
- Clean the pin tips regularly with isopropyl alcohol (IPA above 90%) on a swab or brush.
- Blow out dust around the pin bases with compressed air.
- Press the board straight down (90°). Never push or tilt the pins sideways under pressure.
- Don't over-compress the pins.
Free a stuck pin
- Put a drop of high-purity IPA into the stuck pin's barrel to dissolve the grime.
- Gently work the plunger with a non-metal tool so the spring can push it back up.
- Let the IPA dry completely before powering on.
🚫
Never use oil or grease on the pins. It attracts dirt and ruins the electrical contact.
The board often still works with one or two stuck pins, as long as they still touch the skin. Damage from dirt, contamination or rough handling is not covered by the warranty.
Still stuck?
Ask on Discord (opens in a new tab), open an issue on GitHub (opens in a new tab), or email pieeg@pieeg.com.