Here is a conversation on the OpenBSD misc@ mailing list discussing this specific issue, with this specific hardware.
Please read the posts from Stefan Sperling, an OpenBSD developer who previously attempted this exact task.
I perceive you have five choices. The first four require neither OS driver development skills nor engineering documentation from the hardware manufacturer.
- Use FreeBSD.
- Use Linux.
- Use Windows.
- Use other hardware.
- Develop a driver for your preferred BSD.