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Help with Sega MIDI Steering Force Feedback - Signal Type and Protocol

winteriscoming

winteriscoming

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Does anyone have knowledge about the protocol used for the Sega MIDI steering boards (838-14174)?

My eventual goal is to come up with a translator board that allows this FFB to be used with a couple of other games, including Wangan Midnight Maximum Tune 1/2 (which uses RS232 and I've started decoding the protocol for it).

I can't find very much information about these boards. I was thinking the signal wiring looks like RS422, but the fact that it's labeled MIDI confuses things for me. I'm not sure where to start with trying to sniff the signals not knowing the initial type of signal I'm sniffing. My brief research of MIDI doesn't come up with any MIDI standard that uses TX+/- and RX+/-, per the labels on the signal wires in the wiring diagrams.

Any advice is appreciated.
 
If I'm understanding MIDI wiring, a typical 1-way wiring consists of:
-Shield/Ground
-5V (Current Source)
-Signal (Current Sink)

So if we're dealing with 2-way communication, how do the labels from the board align with MIDI?
I would assume we're dealing with one set of MIDI IN and one set of MIDI OUT.

MIDI Plug FFB.png

So we've got 5 wires here. A shared shield, so each set should have a 5V and Signal?
 
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I know Naomi ID and ClubKart games uses Yamaha AICA MIDI port for drive board communication, AICA midi is 2 pins only - midiin and midiout, but I don't know how they wired to CN9 2x TX and 2x RX pins, perhaps ignore '-' and '_R' and use only TXD and RXD ?
 
MetalliC said:
I know Naomi ID and ClubKart games uses Yamaha AICA MIDI port for drive board communication, AICA midi is 2 pins only - midiin and midiout, but I don't know how they wired to CN9 2x TX and 2x RX pins, perhaps ignore '-' and '_R' and use only TXD and RXD ?
Click to expand...
I think 2 pins at the AICA IC makes sense, but per the wiring on that page you linked, there has to be a 5v source and the MIDI out pin would be used to sink an opto isolator at the receiving end that sinks the receiver's input pin to ground. Then the input for the AICA IC would likely be sunk to ground via an opto isolator that's driven by the FFB board's output.

I only briefly reviewed the spec, and opto isolation appears to be a requirement. I don't know whether or not it's required per the spec, but the device that's sending out the MIDI signal seems to be responsible for supplying source current to the opto isolator located at the device receiving the MIDI signal.

So if we go with that logic, it makes sense that 2 wires would be needed for in and 2 for out, and that the AICA IC would only need 2 pins, because the other required wiring goes to other components.

The challenge as far as I can see it is going to be sniffing these signals and interfacing with the MIDI board. I've so far done my serial programming in python with pyserial using an RS232 adapter. I'm not sure what I'd need in order to read/write MIDI from a python perspective, and not sure if I'd end up with baudrate issues when I ultimately try to translate from one standard to the other (i.e. WMMT's RS232 FFB signals to the Sega MIDI FFB board).
 
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@winteriscoming
@MetalliC

it's possible to convert these midi signals for acepptable on umbalanced motors used in ordinary joysticks, like the Xbox 360 controller?
 
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I also dismantled my xbox controller and conected wire per wire to the buttons to the jvs 60 pin input, using a cable of a very old DB25 printer
 
I doubt you could wire directly into the MIDI header without some kind of dedicated pcb to accept signals and translate them to shaker motor movements. The NAOMI probably expects specific replies back.

I haven't personally started looking in depth at the MIDI interface yet.
 
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