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Spool Inspector

Flash Firmware

Install or update Spool Inspector firmware directly from your browser.

Spool Inspector (ESP32-S3)
XIAO ESP32S3 Sense with OV5640 camera, HX711 load cell, SSD1306 OLED

Before you begin

  1. Put the board in boot mode: Hold the BOOT button on the XIAO while plugging in the USB-C cable. Hold for 2 seconds, then release. The OLED will stay blank — this is normal.
  2. Make sure no other program (Arduino IDE, serial monitor) is using the port
  3. Click Install Firmware below and select the serial port — look for "USB JTAG/serial debug unit" (it may say "paired" at the end)
  4. The flash may take 30-60 seconds with no visible progress. Wait for it to finish, then press the RESET button on the board. If the OLED shows the setup screen, it worked.

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Loading flasher...

After installation

  • The device will reboot and show the setup screen on the OLED
  • Long-press the left button (3s) to enter WiFi setup mode
  • Connect to the SpoolInspector-Setup WiFi network and configure your settings

Alternative: One-click flasher (recommended)

Download the flasher package for your platform. Extract the zip, put the board in boot mode, and double-click to flash. No Python or other tools required.

How to use:

Windows:

  1. Extract the zip
  2. Hold BOOT on the XIAO while plugging in USB-C. Release after 2 seconds.
  3. Double-click flash.bat
  4. Wait for "SUCCESS" (30-60 seconds), then press RESET

Mac:

  1. Extract the zip
  2. Hold BOOT on the XIAO while plugging in USB-C. Release after 2 seconds.
  3. Open Terminal and run (first time — allows esptool + flashes):
cd ~/Downloads/SpoolInspector-Flasher-Mac && xattr -d com.apple.quarantine esptool && chmod +x flash.sh && ./flash.sh
  1. Wait for "SUCCESS" (30-60 seconds), then press RESET

The OLED should show "Setup Step 1 — WiFi Not Set Up"

Advanced: Manual flash with esptool

If the flasher packages above don't work, you can install esptool separately and flash the raw firmware file.

Install esptool:

Windows: Download from GitHub Releases (standalone .exe, no Python). Mac/Linux: pip install esptool

Download firmware:

Flash command:

esptool --chip esp32s3 write-flash 0x0 spool-inspector.bin

Add --port COM3 (Windows) or --port /dev/cu.usbmodem101 (Mac) if it can't find the port.

For more details, see the build guide.

Having trouble? See the Spool Inspector docs for detailed build instructions and troubleshooting.