USB <-> DC High speed Cable Coders released

CyberMick · Post by **CyberMick** » Tue Mar 08, 2005 6:26 am

Even if you did add the second crystal and a jumper the added $2 dollar increase would still make it a worthwhile buy in my book and the 500K still better than the Lik-Sang serial coders cable.

The re-design does sound excellent though and I wish you luck with this project and in trying to get all the bugs out of the system.

neoak · Post by **neoak** » Fri Mar 11, 2005 7:34 am

Axlen wrote:Ack! Really. I will go back and double check the mailbox. Please re-submit.

Don't worry, it seems that Yahoo sent your email to the Junk folder. Don't know why. Anyway, do i send the email to coderscable@etc?

And for the redesign, that means you are opening preorders again?

Axlen · Post by **Axlen** » Sun Mar 13, 2005 9:46 am

neoak wrote: Don't worry, it seems that Yahoo sent your email to the Junk folder. Don't know why. Anyway, do i send the email to coderscable@etc?

And for the redesign, that means you are opening preorders again?

If I can get this into an EASY to build format without any surface mount components then I'd considers opening things up again. And of course the device has to work for more than me and a handfull of other users

I've already ordered some PIC development tools and have a sample part in my hands already.

By the way, for those who might be interested I put up the CAD files for current USB Coders Cable: Rev-F Schematic and Layout. This does not include any crystal switching jumpers or sockets. So if you feel inclined to get your hands dirty with Eagle and improve the current design yourself; have at it. Just be sure to observe the GPL and copyright info in the ZIPed package: USBCC-F.ZIP

Axlen · Post by **Axlen** » Mon Mar 21, 2005 8:07 pm

Here's a picture of the basic development setup for the USB coders cable redesign. No USB cable yet since I'm just testing the development environment and getting used to the IDE. These PIC chips are really neat to play with.

Sourcing all through-hole parts for this version has been going great so far. Just discovered Spark Fun Electronics: a place that does prototype double sided PCB's with soldermask and silkscreen for $2.50 per square inch. As you might well have guessed I'll be making every effort to make this board as small as possible to keep costs to a minimum.

ToeJam · Post by **ToeJam** » Thu Mar 24, 2005 12:51 am

Yay? I can't wait to get one.

Axlen · Post by **Axlen** » Tue Mar 29, 2005 8:38 pm

Quick update: I can't get this PIC chip to operate as I originally envisioned with dual clocks. It can do it, but only for low power, low frequency modes. So the maximum baud I've been able to calculate that will be common to both the DC and this USB-Serial device is 781249 and 800000 respectively. That's 2.4% baud error, but acceptable. So not as speedy as I had originally hoped, but not bad either. I'll be building up a prototype for actual tests over the next week or so. The hardware is pretty simple, but the software/firmware for the PIC will take a little while to get working properly.

The code is based on the Microhip USB CDC demo/tutorial so it will look like a serial/modem type of device to Windows 2K/XP, and Linux kernel 2.6+. Not sure about OS/X.

If this works it will probably be sold as a hobbyist type of kit since it will be using Microchip's USB VID/PID for their CDC demo. I intend to install the bootloader into the PIC so the device will be field upgradeable (firmware wise) via the USB port.; e.g. a real software hackers playtoy! All the development tools (IDE, assembler, C compiler, etc.) are available from Microchip online for free!

CyberMick · Post by **CyberMick** » Thu Mar 31, 2005 4:35 pm

New cable is looking great, look forward to seeing its final release.

Hilltopper · Post by **Hilltopper** » Thu Mar 31, 2005 4:43 pm

just a random question here. could you in theory use this cable to connect a DC to a cable/DSL modem and (with the proper homebrew software) connect to the internet?

Axlen · Post by **Axlen** » Thu Mar 31, 2005 6:17 pm

Hilltopper wrote:just a random question here. could you in theory use this cable to connect a DC to a cable/DSL modem and (with the proper homebrew software) connect to the internet?

No. This is a down-stream USB device. That is to say it is a device that gets attached to a host most commonly a personal computer.

This is a common misconception with USB devices. Devices like keyboards, mouse (mice), modems, printers, etc., don't have the ability to attach to each other, just to a host like a PDA, PC, etc.

More to your question though, the DC would need to have a USB Host Controller chip and drivers. To be useful it would probably need to be interfaced to the DC's parallel port although I actually considered building a device that plugs into the DC's game controller ports; A linux based controller with USB host controller/HUB for connecting USB devices like JumpDrives, wireless ethernet , modems, etc. A major shortcoming of this approch is the rather limited speed of the Maple Bus (2mbs). Though it might make for a fun project.

Hilltopper · Post by **Hilltopper** » Thu Mar 31, 2005 11:04 pm

oh well, it was worth a try. I guess you could still hook it up to your PC, and have the DC connect to the internet through your PC with the proper DC and PC software right?

Axlen · Post by **Axlen** » Fri Apr 01, 2005 7:44 pm

I don't like not being able to run the connection speed at 1.56M baud, therefore I have decided to add an external USART in the form of a second PIC microcontroller. Communications between the two PICs will be via the Serial Peripheral Interface (SPI). It keeps the interface between the chips simple (3 lines) and gives me the oppourtunity to customize the operation of the device to this application. So now the two main parts are the PIC18F2550 (4Mhz Xtal/48Mhz Pll)which handles the USB interface and the PIC18F252 (25Mhz Xtal) which will be programmed to serve as a serial USART.

A sample part is on its way from Microchip.

Axlen · Post by **Axlen** » Fri Apr 01, 2005 7:53 pm

Hilltopper wrote:oh well, it was worth a try. I guess you could still hook it up to your PC, and have the DC connect to the internet through your PC with the proper DC and PC software right?

That would work. A SLIP or PPP type of interface could probably be devised. I think the TCP/IP stack in KOS could support that. I seem to remember someone posting some code for the DCs modem.

Hmm, now that you bring that up I just had an idea. How about a USB-Maple bus cable. A driver could be developed for dcload and KOS that would allow hi-speed communications via the Maple bus. 2Mbs would beat 1.56M baud and I could probably do it without the second PIC chip. I think this idea deserves some thought and experiments to test the concept.

Axlen · Post by **Axlen** » Wed Apr 06, 2005 9:34 pm

Well I read through the Maple bus patent and the Maple bus info posted on Marcus's DC programming pages. I think it would be possible to pull off a USB-Maple coders cable but I can't say for sure that the serial throughput would be. I looked the KOS 1.3 maple bus code to try and get a feel for how the host side functions work. Neat stuff. I'll keep you posted when I actually start doing some experiments.

Axlen · Post by **Axlen** » Mon Apr 25, 2005 8:28 pm

Just a quick update: I've been busy with family activities a lot the past few weeks, but still managed to spend some time learning more about USB and the PIC microcontroller chip. Currently my efforts are in making sure drivers for Windows, Linux, OS/X and BSD will be available. A lot of time has also been spent reading through the USB framework and driver code for the PIC and trying to wrap my head around that and how it all interoperates. This is far more complex project then using the FTDI USB-Serial chip, but I think the end result will be worth the effort. Gotta run and pick up my daughter... later.

Hilltopper · Post by **Hilltopper** » Mon Apr 25, 2005 9:30 pm

thanks for the update

Prophet][ · Post by **Prophet][** » Wed Apr 27, 2005 6:15 am

seems the microcontroller has become quite the tool in DC hardware world this year

Axlen · Post by **Axlen** » Wed Apr 27, 2005 8:04 pm

FYI

Here's a nifty link to little USB-Serial breakout board that could be used as the basis of a DC coders cable for anyone whose interested in building their own. You would be limited to 500K baud, but that's still pretty darn good! Marry this up with the schematics I've already published; add some inspiration and perspiration and you can have your own USB-Serial Coders Cable

Look for here at Spark Fun Electronics

CyberMick · Post by **CyberMick** » Tue May 24, 2005 9:03 am

Hi Axlen,

Have you still developing this USB Coders Cable or have you abandoned the project?

If you are not continuing with the project then that is a shame but I understand. It was a great effort though and I suppose we could build our own from your schematics but I don't trust my workmanship.

Smurph · Post by **Smurph** » Tue May 24, 2005 10:51 am

I'll have to try building it! I just need to get some money for parts... and drivers for my PC...

Axlen · Post by **Axlen** » Mon Jun 06, 2005 8:00 pm

I've decided to stop all coders cable development. No excuses, no explanation. Period.

USB <-> DC High speed Cable Coders released

Bits and pieces

New design in progress

USB USB USB

Log book 31 March 2005

Initial review of USB-Maple based coders cable concept

USB-Serial Breakout board from Spark Fun Electronics

Sigh...