Serial Interface
Ok, to get anything running on your Dreamcast you need a serial interface, Have a read of Marcus’ instructions on how to build one, then pop-back here for some extra notes.
I didn’t have a spare Null-Modem cable lying around for mine, so I used a female 9 way serial sub-d connector on the end of a lead which was directly connected to my circuit. To wire the circuit upto a female connector you need to adjust the pinouts, the take the pinouts from marcus’s site then use the following mappings to connect the female connector up.
| 9 Way Male | 9 Way Female |
|---|---|
| 2 | 3 |
| 3 | 2 |
| 7 | 8 |
| 8 | 7 |
Also, with the NeoGeo end of the cable, I cut the Yellow cable before it goes into the connector and soldered that to the +3v supply instead of soldering another wire to the board and running that along side the exisiting NeoGeo end of the cable, this provides a much neater solution. Then, when you cut the NeoGeo end of the cable you’ll notice there’s no yellow wire! The shielding is where the yellow cable went on the PCB end of the cable, so just twist this up, and use some heatshrink on it, then solder it to your circuit board.
When connecting wires to your circuit board, use little pins that stick up through the board, and then solder the wires to the pins. Then you can put heatshrink tubesover the pins and the wires, making it much neater, and less likely to short out on anything.
I also used a socket for the MAX3222, if you dont you risk overheating the IC with your soldering iron. And, if you make a mistake it’s easier to start over again and you won’t have wasted an expensive IC.
Here’s a picture of mine:
Ok, to get anything running on your Dreamcast you need a serial interface, Have a read of Marcus’ instructions on how to build one, then pop-back here for some extra notes.
I didn’t have a spare Null-Modem cable lying around for mine, so I used a female 9 way serial sub-d connector on the end of a lead which was directly connected to my circuit. To wire the circuit upto a female connector you need to adjust the pinouts, the take the pinouts from marcus’s site then use the following mappings to connect the female connector up. 9 Way Male 9 Way Female 2 -> 3 3 -> 2 7 -> 8 8 -> 7
Also, with the NeoGeo end of the cable, I cut the Yellow cable before it goes into the connector and soldered that to the +3v supply instead of soldering another wire to the board and running that along side the exisiting NeoGeo end of the cable, this provides a much neater solution. Then, when you cut the NeoGeo end of the cable you’ll notice there’s no yellow wire! The shielding is where the yellow cable went on the PCB end of the cable, so just twist this up, and use some heatshrink on it, then solder it to your circuit board.
When connecting wires to your circuit board, use little pins that stick up through the board, and then solder the wires to the pins. Then you can put heatshrink tubesover the pins and the wires, making it much neater, and less likely to short out on anything.
I also used a socket for the MAX3222, if you dont you risk overheating the IC with your soldering iron. And, if you make a mistake it’s easier to start over again and you won’t have wasted an expensive IC.
Here’s a picture of mine:
I’ve not boxed mine up yet, here you can see what I was talking about the the wires being soldered to pins that stick through the circuit board. The wires with the black boots are for the RS232 cable, the wires with the pink boots go to the NeoGeo box which plugs into the back of the DC.
If you want to test the circuit after it’s built you can connect the TX and RX TTL level wires together and use a terminal program on your pc and you should see keypresses echoed back to the screen (if localecho is enabled in the terminal program then you’ll see two of each keypress echoed to the screen).
Here’s a PDF file detailing the MAX-3222-CPN IC.
Here’s another picture of my set-up:
Nice huh ?