NOTE: THIS IS REALLY OLD. For something newer and more interesting,
Since there's really only one thing here, which is the serial cable info, I'll just
dump it into this page. If I get more in the future (which is unlikely =) then I'll
seperate this out into sections. For now though...
DISCLAIMER. I am not an electrical engineer, I am a computer programmer.
I may have had some hobbyist skills in soldering and electronics, but I am by no means
qualified to say that this circuit is complete, or that it even works under most
circumstances. All I can say is that it works for me, and if you build it, you may
be inviting a great deal of woe into you and your systems =). If it breaks something
(or you break something in the process of building it), I will not be held responsible.
By following these directions, you're agreeing with me to take your own responsibility
in this matter!
Basically most of the interesting stuff is covered elsewhere, and so I'll give
links to the relevant info. First off, get
the datasheet for the MAX232/233.
You'll want to find the page showing the pinouts for the MAX233, and print that out. Or if
you have plenty of screen space and your soldering equipment is by the computer, then view
it on-screen. In my copy of the PDF, you'll want to hit page 21 and keep the top half of
that page handy (caption: "Figure 11. MAX233/MAX233A Pin Configuration and Typical
Operating Circuit"). This diagram will give you the pinouts for the MAX233, and it's useful
for quick-reference while soldering.
As far as parts go, here are the relevant links:
If Good Luck Games is out of cables (which is possible since they are an import
item), then you'll need to do a bit of searching yourself. Basically the simplest way (and
what I did to find them) is to go to Amazon and search for "Neo Geo". You won't find the
actual cable in the listings, but you can pick out the game houses that have a large stock
of Neo Geo items, and generally they will also have the cable (or can order it for you).
Jameco has the MAX233, which you need to build this particular circuit. The MAX232 is the
same thing, but it requires four more caps. Don't bother.. just get the MAX233. While you're
at Jameco, you should probably also order any other parts you want. That includes a 1uF
capacitor (tantalum or electrolytic will work fine), and if you want to be neat about it,
a perfboard and 20-pin DIP socket, wire, etc. You may also want to buy the PC connector --
I built my cable with a female connector, not a male. This lets you attach it
to your PC without a null-modem connector. The pinouts below match that setup.
Once you have this stuff, here is the connection chart. It helps to have this handy, and/or
print it out, and/or draw a little schematic for yourself on the printed out MAX233 sheet. It
is important to make sure you don't get any crossed wires, shorts, etc, because a nice +12
going into your DC's +3.3 port could spell trouble.
Connect the MAX233 power supply:
- Hook pins 12 and 17 together
- Hook pins 11 and 15 together
- Hook pins 16 and 10 together
- Hook pins 6 and 9 together
- Hook pin 7 to the PC's DTR (pin 4)
- Hook pin 7 to the positive (+) side of the 1uF capacitor,
and hook the negative (-) side of the capacitor to ground.
Attach the Dreamcast cable:
All of the following may be obtained by cutting
the wire that originally went to the Neo Geo.
- Hook ground (Dreamcast RED) to pin 6/9 of the MAX233
- Hook TXD (Dreamcast WHITE) to pin 2 of the MAX233
- Hook RTS (Dreamcast BLUE) to pin 1 of the MAX233
- Hook RXD (Dreamcast BLACK) to pin 3 of the MAX233
- Hook CTS (Dreamcast GREEN) to pin 20 of the MAX233
Attach the PC cable:
- Hook RXD (PC pin 2) to pin 5 of the MAX233
- Hook CTS (PC pin 8) to pin 18 of the MAX233
- Hook TXD (PC pin 3) to pin 4 of the MAX233
- Hook RTS (PC pin 7) to pin 19 of the MAX233
- Hook GROUND (PC pin 5) to pin 6/9 of the MAX233
The whole system will become powered when you plug the cable into your PC and start
up a terminal program. If you want to do some testing, you can try crossing the RXD/TXD
and CTS/RTS lines in the Dreamcast end and pushing some keys on your PC -- this will
verify that the data is making it through the buffers and back through, into your PC.
That's about it! I'd like to put up some pictures, but unfortunately both the cables
I made have already been taped up and put together, because over here we were excited
to start working on things.. ^_^; Good luck!
I'd also like to thank Marcus Comstedt, who
provided the original original cable diagrams, and Mike
"Tursi" Brent who provided the info on using the MAX233. Also various people on the
DCDev list have pointed out that I was missing the PC ground connection, so I have added
that in there after being reminded by Alex Lau.