USB <-> DC High speed Cable Coders released

Discuss modifications you have done or plan to do to your Dreamcast or any other hardware, or discuss devices you want to build. If your console does not work or is acting up, ask about fixing it in here.
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Post by bizzle » Mon Jun 06, 2005 8:12 pm

Damnit!
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Post by Smurph » Tue Jun 07, 2005 10:37 am

Xylene wrote:Damnit!
My thoughts exactly.
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Re: Sigh...

Post by doragasu » Tue Jun 07, 2005 4:26 pm

Axlen wrote:I've decided to stop all coders cable development. No excuses, no explanation. Period.
Sorry to hear that... Anyway you have made a great work and you deserve to rest.

I was thinking on making a new design on my own, but I don't know what are the DC serial bus standard speeds. Can anybody tell me or point me to the right documentation?

I can't find here the F232 chip so I think I can use a TUSB3410, but it isn't as fast as the F232 (up to 921,6 Kbps only).

If I can find info on the DC serial port standard speeds, I think I'll go for it when I finish my exams...
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Re: Sigh...

Post by Axlen » Tue Jun 07, 2005 9:14 pm

doragasu wrote: I can't find here the F232 chip so I think I can use a TUSB3410, but it isn't as fast as the F232 (up to 921,6 Kbps only).
You can get the FTDI chips from Parallax.

The bauds that the DC serial port supports are based on a 50Mhz clock. The formulas for determining the baud are in the hardware manual for the processor. You can probably get links to those resources off the Boob website and from Marcus's site as well.

The major problem will all single chip USB-serial solutions is that fact that their clocks are all some factor of 96Mhz or 48Mhz which makes choosing bauds that are compatible between the USB bridge and DC serial port a real challenge. Especially so at the higher bauds. 500K baud is the maximum *reliable* baud I could coax out of the FTDI FT232BM chip (6Mhz clock) when used with the Dreamcast.
Axlen was here...
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Post by Smurph » Wed Jun 08, 2005 7:10 am

500MHz is still very good when compared to the serial port on a computer.
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Re: Sigh...

Post by doragasu » Wed Jun 08, 2005 7:32 am

Axlen wrote:You can get the FTDI chips from Parallax.

The bauds that the DC serial port supports are based on a 50Mhz clock. The formulas for determining the baud are in the hardware manual for the processor. You can probably get links to those resources off the Boob website and from Marcus's site as well.

The major problem will all single chip USB-serial solutions is that fact that their clocks are all some factor of 96Mhz or 48Mhz which makes choosing bauds that are compatible between the USB bridge and DC serial port a real challenge. Especially so at the higher bauds. 500K baud is the maximum *reliable* baud I could coax out of the FTDI FT232BM chip (6Mhz clock) when used with the Dreamcast.
Thanks for the info. I have only had an overview on datasheet of the chip I plan to use (I'm pretty busy ATM), and it uses a 96MHz clock signal to get the baudclock, so it looks like I'll have the same problems you had. Anyway, I'll be pretty happy if I can get 500Kbps.
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Post by doragasu » Wed Jun 08, 2005 10:33 am

I've been looking to the SH4 manual (thanks Axlen for pointing me to it) and I think I now know how to calculate the baudrates. The max baudrate for Asynchronous mode is with n=0 (CKS1=0, CKS0=0) and N=1:
50.000.000/(64*0,5*1) = 1.562.500 bps

For 500Kbps I suppose you use n=0 and N = 3 (520833 bps).
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Post by semicolo » Fri Jun 10, 2005 11:50 am

Yes you're right, if you want exact matching baud rates you could use an USB uC and hook a standard Uart clocked at 25Mhz on it. Or maybe use some fast uC like a scenix to emulate one or find a uC that's got an embedded uart that can be clocked fast enough.

You'll have to write device drivers though whereas FTDI chips come with.
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Post by doragasu » Fri Jun 10, 2005 4:22 pm

semicolo wrote:Yes you're right, if you want exact matching baud rates you could use an USB uC and hook a standard Uart clocked at 25Mhz on it. Or maybe use some fast uC like a scenix to emulate one or find a uC that's got an embedded uart that can be clocked fast enough.

You'll have to write device drivers though whereas FTDI chips come with.
I hope I have not to use a generic uC, as I started to read the entire USB 2.0 specification (more than 600 pages) and it's really complex. If I have to code everything, I'll never gonna end this.

I'll finish my exams on 25th June, and then I'll have a little more time to spend with this project (I'm also working so it will progress slowly even when I finish my exams). By now I have found a general purpose USB controller (TUSB3210) with an embedded 8052 uC running at 48MHz. I'll try to connect it to a TL16C550D UART chip, that supports... up to 1.5 Mbps!

I have no experience working with USB devices or developing drivers, but the USB controller comes with a free "Product development kit" so I hope developing the drivers is no a PITA. It also has Keyboard firmware sample source code, I'll try to have a look at it and see how does it look like.

Let's see where I can get with this.
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Post by Axlen » Sun Jun 12, 2005 12:38 pm

semicolo wrote:Yes you're right, if you want exact matching baud rates you could use an USB uC and hook a standard Uart clocked at 25Mhz on it. Or maybe use some fast uC like a scenix to emulate one or find a uC that's got an embedded uart that can be clocked fast enough.

You'll have to write device drivers though whereas FTDI chips come with.
Yup, the baud matching problem is known as aliasing. As long as the bauds are within 3% the serial link should work.

FYI: Olimex has a nice cheap PIC development board with an FTDI USB-serial chip on board: http://www.olimex.com/dev/pic-p28-usb.html

A hobbyist could use that to build up a 500K baud DC Coders cable with the addition of a few components. I've already provided the DC interface details and wrote up the theory so what's taking this group of hardware modders so long to get with the modding! :D
Axlen was here...
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Post by Christuserloeser » Sat Aug 20, 2005 3:14 pm

*Bump* Someone should sticky this topic :wink:
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Post by CYRiX » Sat Aug 20, 2005 7:03 pm

is there someway to use this to connect the dreamcast online? I mean I know computers can connect to each other for internet, why not a dreamcast?
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Post by Skynet » Sat Aug 20, 2005 9:58 pm

That can be done via the modem.
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Post by CYRiX » Sun Aug 21, 2005 3:03 pm

yea but using this gives it 1mb/s instead of like 33.3kb/s so it would run fps games smoothly.
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Post by doragasu » Mon Aug 22, 2005 5:23 am

It could maybe be used for new homebrew released, but not for previously released games.
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Post by Morphv2 » Tue Aug 23, 2005 8:49 pm

You have a profound point doragasu. But heres the catch, not many games/apps as it is support the official BBA. A cheaply built DC serial-BBA could the the thing needed for future DC homebrew coders. Heck if a *standard* format could be achieved, a universal homebrew BBA could be made with support for future games like a networked Quake port or something. 1.5Mb/s is plenty for online games.
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Post by bender » Tue Aug 23, 2005 9:16 pm

I see a homebrew BBA or the USB- dc serial something that future devvers will need. Most laptops actually don't have a serial port and seems that the standar serial it's going to disappear in some years, there's not much use unless you are doing some coding with homebrew hardware and PICs, comunication through serial it's just too slow :(
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Post by ghostparty » Tue Aug 23, 2005 10:23 pm

GyroVorbis wrote:If I wasn't a 15 year old unemployed 10th grade bum who can't even drive yet, I wouldn't think twice about buying me one of them.
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Post by Christuserloeser » Wed Dec 28, 2005 12:13 am

Christuserloeser wrote:*Bump* Someone should sticky this topic :wink:
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Post by Prophet][ » Wed Dec 28, 2005 12:16 am

if your going to sticky this, their is about 50 other topics you could also sticky.

People can search if they really need this.
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