# Page Not Found

The URL `chapter4` does not exist.

You might be looking for one of these pages:
- [Welcome to Petoi Doc Center for Bittle, Bittle X & Nybble](https://docs.petoi.com/master.md)
- [Battery](https://docs.petoi.com/technical-support/battery.md)
- [Useful Tools](https://docs.petoi.com/technical-support/useful-tools.md)
- [Serial Protocol](https://docs.petoi.com/apis/serial-protocol.md)
- [Controller](https://docs.petoi.com/mobile-app/controller.md)

## How to find the correct page

1. **Browse the full index**: [/sitemap.md](https://docs.petoi.com/sitemap.md) - Complete documentation index
2. **View the full content**: [/llms-full.txt](https://docs.petoi.com/llms-full.txt) - Full content export

## Tips for requesting documentation

- For markdown responses, append `.md` to URLs (e.g., `/master.md`)
- Use `Accept: text/markdown` header for content negotiation