Looking for high-speed serial protocol (FPGA implementation)

I've found that my vendor has a 4-wire RS-485 full-duplex connection into 
an FPGA fast enough to handle 5-10 Mbits, and I'd like to coordinate 
communication using that interface (together with some isolators). What 
would be a good protocol for exchanging packets of 4-20 32-bit words, with 
acknowledges? I need to exchange simple command/reply sequences, receive 
asynchronous events, and send/receive bulk data (firmware updates, realtime 
sensor data). I figure something with embedded clock and data over 2 wires 
is needed, but don't know what options are available. 10 Mbit Ethernet and 
HDLC come to mind, though. Multi-drop would be a plus, with devices wired 
in a daisy chain. On the host side I want to use a tiny Linux card, so a 
protocol with good hardware support in SBCs would be nice.

Kenneth Porter wrote:

> I've found that my vendor has a 4-wire RS-485 full-duplex connection into 
> an FPGA fast enough to handle 5-10 Mbits, and I'd like to coordinate 
> communication using that interface (together with some isolators). What 
> would be a good protocol for exchanging packets of 4-20 32-bit words, with 
> acknowledges? I need to exchange simple command/reply sequences, receive 
> asynchronous events, and send/receive bulk data (firmware updates, realtime 
> sensor data). I figure something with embedded clock and data over 2 wires 
> is needed, but don't know what options are available. 10 Mbit Ethernet and 
> HDLC come to mind, though. Multi-drop would be a plus, with devices wired 
> in a daisy chain. On the host side I want to use a tiny Linux card, so a 
> protocol with good hardware support in SBCs would be nice.

You can do almost anything in a FPGA, so you'd be best working
backwards from the tiny Linux card.
How fast do you actually need to go ?
Look at FTDI and Silabs for USB<->Serial options.

-jg