Dreamcast & Ipac converter box wiring queries

[Grasshopper]

Hi all,

I'm intending to build a number of control panels and I want to be able to use all of them to play games on either my PC or Dreamcast.

My plan is to build two convertor boxes. One will contain two hacked Dreamcast controllers and the other an Ipac. The converter boxes will connect to the panels using 36 pin centronics cables.

I'm trying to come up with a plan that is as general purpose as possible and that is also reasonably future proof.

My provisional pin arrangement is as follows.

1  +5 Volts
2  0 Volts
3 Button Ground
4  Player 1 Joystick Up
5  Player 1 Joystick Down
6  Player 1 Joystick Left
7  Player 1 Joystick Right
8  Player 1 Button 1
9  Player 1 Button 2
10  Player 1 Button 3
11  Player 1 Button 4
12  Player 1 Button 5
13  Player 1 Button 6
14  Player 1 Button 7
15  Player 1 Button 8
16  Player 2 Joystick Up
17  Player 2 Joystick Down
18  Player 2 Joystick Left
19  Player 2 Joystick Right
20  Player 2 Button 1
21  Player 2 Button 2
22  Player 2 Button 3
23  Player 2 Button 4
24  Player 2 Button 5
25  Player 2 Button 6
26  Player 2 Button 7
27  Player 2 Button 8
28  Admin Button 1 (Player 1 start)
29  Admin Button 2 (Player 2 start)
30  Admin Button 3 (Player 1 Coin)
31  Admin Button 4 (Player 2 Coin)
32  Admin Button 5 (Haven't decided what this does yet)
33  Admin Button 6 (Haven't decided what this does yet)
34  Num Lock LED
35  Caps Lock LED
36  Scroll Lock LED

The order of the inputs is not really important and will probably change. I'll probably try to keep the +5V, 0V, and button grounds as far apart from one another as possible to avoid shorts.

Ideally, I'd like to have two ports on the side of the box, one for player 1 and one for player 2. The pins for player 1's port would be as above. The pins for player 2's port would be the same except that pins 4-15 would be swapped with pins 16-27.

The idea is that the converter box could be used with either a single 2 player panel, or two separate 1 player panels. A 2 player panel would simply plug into port 1. A 1 player panel would plug into either port 1 or port 2 but would always be wired up as player 1. When you attached a single player panel to the second port it would become player 2 because of the swapped round pins.

I've kept the admin buttons separate. The idea is that the admin buttons will always do the same thing regardless of which port the panel is plugged into. So for example the player 1 start button would always start player one even if the panel was plugged into port 2. This would ensure that the buttons were always labelled correctly.

The only problem with my pin arrangement is that it assumes all the buttons can share the same ground. It has recently been established in another thread that this assumption is valid for the Dreamcast but what about other consoles?

If it turns out that separate grounds are needed then I've got a problem as I've run out of pins. Running separate player 1 and 2 grounds would actually require the use of 4 ground pins, one for player 1 controls, one for player 2 controls, one for player 1 admin, and one for player 2 admin. This is because when the player buttons are swapped the corresponding grounds have to be swapped as well, however the admin grounds have to remain static.

One solution would be to have separate cables for the player 1 and player 2 controls. This would free up loads of pins. However, it would mean that I'd have to use two thick cables to connect a two player panel, a bit clumsy but not the end of the world I suppose.

Another possibility would be to free up some of the pins I've reserved. For example, I think it's unlikely that I'll ever need 8 buttons per player. I went for 8 buttons because that is the number of buttons on a Playstation controller but I doubt that many, if any, Playstation games need all 8 (can anyone verify this?). I don't currently own a Playstation and nor do I intend purchasing one in the near future but I'm trying to be as future proof as possible.

I could also free up a pin by not using the Scroll Lock LED (do any MAME games use that LED?).

I could also possibly make do with just 4 admin buttons and use some sort of shift key arrangement to get all the functions that I need. Alternatively, perhaps I could put some of the admin bottuns on the converter box itself.

Decisions, decisions, decisions...

Any thoughts or comments would be appreciated.

[Dave_K.]

Wow, thats a whole lot of connections for a single cable!  Whats the 0V for?

As for grounds, I don't think you will have a problem (as we established the DC works fine sharing grounds between controllers).  

You didn't mention how you were going to swap between PC and Console systems (assuming you kep the same 2 player panel plugged in).

IMHO a single cab playing every type of configurate system and control panel is a noble goal, but is it really worth all that trouble?  Reconfiguring everything around to play something else will become a pain, and you will find yourself leaving it in a particular setup for longer periods of time (thus defeating the purpose of adding all that extra functionality).  Heck, I have 2 cabs dedicated to consoles alone!  

[Grasshopper]

Well it looks like the decision has been made for me. I'd already bought some Centronics cables and a Centronics switchbox. The idea was that I would gut the switchbox, put my Ipac inside it, and wire the Ipac up to the Centronics sockets.

However, last week I opened up the switchbox and noticed that not all of the 36 pins on the sockets are used. A quick test with my multimeter confirmed the same applied to the cables. D'oh, that'll teach me for making assumptions. I'm waiting for a reply to an email I've sent to the manufacturers (Belkin) to get confirmation of how many pins are actually used, but visually I'd guess about 25.

So it looks like I'll need two cables for a two player panel unless I can find some 36 core Centronics cables (which might not actually exist) or I make my own (too much hassle).

Actually I think it's a blessing in disguise as it's forced me to rethink my whole approach, and I've realised that I've been making my life unnecessarily complicated.

The problem I had was that I spend most of my time playing classic arcade games, and most of them offer two player alternating play. For authenticity I believed that even on a single player panel you needed to have working player 1 and player 2 start buttons. This meant you needed access to start buttons from two controllers if you were using your control panel with a games console.

Anyway, I thought about it a bit more and realised that console games are almost never alternating play (someone correct me on this if I'm wrong) and so for modern console games you only ever need to have one start button per panel wired up. This means I'll only ever need one common ground for a one player panel. Problem solved!

Dave_K, the 0v is there in case I decide to use perfect 360 joysticks.

I'm not actually building a cab at this stage just control panels. So switching between the PC and DC is simply a case of attaching the appropriate panel to the appropriate converter box using one of the Centronics cables.

My ultimate long term goal is to build a cab. But by the time I have the space, time and money to do this, we'll probably have full speed DC emulation on a PC anyway, so none of this will be an issue!

[Dave_K.]

Anyway, I thought about it a bit more and realised that console games are almost never alternating play (someone correct me on this if I'm wrong) and so for modern console games you only ever need to have one start button per panel wired up. This means I'll only ever need one common ground for a one player panel. Problem solved!

True, modern console games don't usualy have two player alternating play.  But you wlil still need to have two start buttong wired up for the control panel (one for each player side).  How else can player 2 "join" in the game in something like fighters!?  Maybe I didn't understand what you were saying?

My ultimate long term goal is to build a cab. But by the time I have the space, time and money to do this, we'll probably have full speed DC emulation on a PC anyway, so none of this will be an issue!

Don't build a cab, just buy an Midway 4 player cab (NBA Jam and the like) for around $300.  Then use your control panel top.  Will save you time and money in the long run.

[Rawker]

grass if you have icq hit me up on 118287640 and i'll help you out.