Bullet R2·Help

Quick Start

Follow these steps to update your Bullet R2 using the web updater.

1. On Windows, remove the WinUSB driver so the device shows up as a serial COM port. (Skip on macOS/Linux.)
2. Enter Bootloader Mode: Press and hold Power Down, then turn on the Bullet. (The display will blink in Bootloader mode.)
3. Connect: Click Connect USB CDC and select your device.
4. Select Firmware: Choose your bullet_io.bin file.
5. Upload: Click Upload Firmware and wait for completion.
6. Restart: Power cycle the Bullet after the upload completes.

Select USB, then connect

Web updater interface

Windows Desktop Updater (Optional)

If you prefer the Windows desktop updater, follow these steps.

Uninstall the WinUSB Driver (First Time Only)

Open Device Manager (Win + X). Under Universal Serial Bus devices, find Aillio LTD - Bullet R2 CDC.

Right-click, then select Uninstall device.

In the confirmation dialog, enable Delete the driver software for this device, then click Uninstall.

Select the checkbox to remove the driver software.

Run the bullet_r2_firmware_update.exe

Or Run the Bullet R2 Firmware Update-Setup-1.0.0.exe

Windows desktop updater

Links

Official Resources

Documentation

Software

Frequently Asked Questions

Which browsers are supported?

Use Chrome or Edge on desktop. Firefox and Safari do not support the Web Serial API.

How do I enter bootloader mode?

Turn the Bullet off, then hold Power Down while turning it back on. The LED display will blink when bootloader mode is active.

What if the upload fails?

Try the following:

• Re-enter bootloader mode
• Use a different USB cable or port
• Disconnect and reconnect the device
• Check the log output for details
• Update Chrome or Edge to the latest version

Can I use this on macOS or Linux?

Yes. The web updater works on any operating system that supports Chrome or Edge with Web Serial.

What baud rate is used?

The updater uses a fixed baud rate of 921600 bps.

How long does an update take?

Most updates complete within 1–3 minutes, depending on file size and USB connection quality.

Troubleshooting

Device not shown in the Connect dialog

Check:

• Bootloader mode is active (LED blinking)
• Try a different USB cable
• Try a different USB port
• On Windows, confirm the device appears in Device Manager

Upload hangs or stops progressing

Try:

• Press Esc to cancel the upload
• Disconnect, re-enter bootloader mode, and retry
• Use a high-quality USB cable
• Avoid USB hubs

Wrong device selected

Make sure you selected Aillio LTD - Bullet R2 CDC and that the device shows:

• VID: 0x0483
• PID: 0xA4CD

Web Serial not available

Use Chrome or Edge on desktop, and open the updater over HTTPS (or localhost). Update your browser if needed.

Contact Support

If you still need help, contact support and include your roaster details and the updater log.

When contacting support, include:

• Bullet R2 serial number
• Current firmware version
• Operating system and browser version
• Complete updater log output
• Any error message shown on screen