Getting started on the DC portable

[Blargaman91]

While I'm still waiting for a reply on my post about the best kind of case for the portable, I'm starting my "worklog". I don't think progress can be made with this portable for quite a while, but I am full of questions.

To start off... what the heck, Sega? Your controller is jacked up. I'm seriously unsure how to approach the analog stick and triggers. I don't want to have to use hall sensors in my portable considering all the trouble it may be, so I'm looking for a way to use normal potentiometers. My findings are as follows:
Going to the main controller CPU, the L and R triggers send 1v in their neutral position and about 3v pressed all the way down, hard.
The X and Y axes stand at about 2.7v in their neutral position, 1v at their lowest (left on X, down on Y), and 4v at their highest (right on X, up on Y). I think these numbers are correct, but I might be remembering wrong.
I did only a little experiment and I'm not sure it's possible to make a normal potentiometer-style analog stick fit those parameters. Is it?
And maybe this is all for naught, because I feel like, as always, 3rd party controllers take the easier route and use potentiometers. Do they? I only own official ones.

My next one's about cooling. The metal shielding covering the processors is a pretty large one, but that fan looks pretty tiny. If I can somewhat keep the original shielding and use a better thermal conducting compound, will I really need a fan at all? I know there's more than processors producing heat in a portable, so I figure the answer is yes anyway...

And also, about that fan, what is the deal with the Dreamcast needing it to be plugged in to boot? Is there some fequency produced, some resistance provided, or anything of the sort? I watched a video of the IntoDream and heard a mention that the "wires can't be extended" from the fan to the motherboard. What's that about...?

Regarding VGA as well, I'm unclear on whether all games can work with it or not. I know that some games aren't compatible but I also hear that there is some kind of trick to making them work. Is it possible through whatever trick that is to make any game work?

And, since I just remembered, does anyone know just what 12v is used for? It appears to draw about 60 mA in-game, obviously not much, but it's something, considering the system can't boot without it.

I think I'll have pictures in my next post to make things a little more interesting...

 

[laingsoft]

3rd party controllers take the easier route and use potentiometers. Do they?

Yes

will I really need a fan at all?

Yes

Is there some fequency produced

Yes

wires can't be extended" from the fan to the motherboard. What's that about...?

Bacteria not understanding how PWM signals work

Is it possible through whatever trick that is to make any game work?

No

just what 12v is used for?

Driving the main motor in the DD, and supplying enough to the fan, Serial, and EXT ports.

 

[Blargaman91]

So considering the fan does produce a frequency I know nothing about, what does it take to make the Dreamcast think it's there when it's not?

 

[laingsoft]

I don't remember the frequency of the pulses from the DC fan, but you need to basically send it a pulse of n from an arduino/555 timer or something else.

There are 3 wires coming from the DC fan, GND, VCC, and PWM. You need to pulse the PWM.

 

[RDC]

I realize this thread is a few months old now, and I didn't know about the fan until I opened my DCs here to check on that and do some testing just a bit ago, then the controller info I've had figured out for awhile now. viewtopic.php?f=34&t=12316

The older DC version doesn't use a 3 wire fan.

The ones that do though, the 3rd wire outputs a 50% Duty Cycle pulse at around 266Hz. You can just put a Resistor divider on there from 5v to Ground, so you have 2.5v going to that 3rd wire pin and it will work, it doesn't need to be a pulse.


The official controllers use Hall sensors, but that can be worked around if you need. Between the Hall sensors and MCU are Op-Amps which convert the current changes of the Halls to voltage changes that the MCU on the controller can understand.

All you'd need to do for using a POT style Stick on an official DC controller board is remove the Op-Amp and wire the POT style Stick to the X and Y axis spots, then use Ground and the 5v for the power/ground for the Stick.

The Triggers go from Low to Hi and work the same way. If you'd want to use a POT style Trigger so the Analog feature could be kept, just remove the Op-Amp and wire it the same as the Stick, so that pulling the Trigger makes the voltage go up on the Trigger line.

If you would want to put buttons in place of the Triggers there so they worked Digitally, then after removing that Op-Amp you'd wire a 10k on each Trigger line to Ground, so they stay at 0v when not used, then have your button wired to the Trigger line and 5v and it will go from 0v to 5v and register as a full Trigger pull when it's pressed.