Vinculum Object

crgwbr

Hey,
Now that parallax is selling the Vinculum chip, are there any plans for a vinculum object to be released?

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Paul Baker

Mike Green has already released an object, use search.parallax.com to find it. In short order I will be trying to use it for HID class, and will post the resuts if I am successful.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Mike Green

Here is the thread: http://forums.parallax.com/showthread.php?p=620161

I've stopped working with the Vinculum for now in favor of Rokicki's SD card routines. The main issue for me is that the Vinculum works fine with a human talking to it. It's harder to make it behave when it's a program talking. The Vinculum puts out some unsolicitied and somewhat unexpected messages when you insert and remove USB devices from it. You have to devote a cog to it to listen all the time for these messages and ignore or interpret them rather than picking up status when you want to do so.

crgwbr

Thanks

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Dennis Ferron

So what does the Viniculum allow you to do that you can't do with the SD card object? Does it allow you to read/write USB memory sticks? What about USB cameras?

Mike Green

The Vinculum provides primitive access to human interface devices like keyboards, mice, joysticks. It provides simple access to USB printers (just a serial channel - you need to provide the proper formatting yourself). Memory sticks are what it does best. Cameras, to the extent they look like memory sticks, would work.

The most important thing is that it implements a FAT file system with subdirectories (although with short - 8.3 filenames). Rokicki's object doesn't implement subdirectories (although he has other code that does) and it takes some shortcuts in checking (for efficiency).

Ken Gracey

Mike,

After seeing FTDI's demonstration of the Vinculum chip at Parallax my conclusion was that the best fit for it would be to design an interface that could enable BASIC Stamps, SX, or Propellers to utilize USB memory sticks for external data logging. Past attempts at interfacing memory devices by our customers got stuck with the FAT file system. It always seemed that there was a hangup with coding to manage the file structure from the microcontroller, but the Vinculum is supposed to make that part much easier. The finished product I envisioned would be a small SIP module with Vinculum and a socket for USB memory sticks, and a communication protocol that provided access to a variety of processors with lower code overhead and memory requirements. I'm not sure if a helper chip would be required for the variety of 8-bit microcontrollers our customers like to use.

Does this seem like an ideal application for the Vinculum based on your experience so far? I didn't have much interest in their flashy demos with MP3s and car steros, but I'd really like our customers to be able to read and write to USB memory sticks.

Ken Gracey
Parallax, Inc.

Dennis Ferron

Can you run user code on the Viniculum by itself?

Mike Green

Ken,
As I've mentioned before, the Vinculum and other similar devices would be wonderful peripherals for all of your products, although the Propeller is a special case. For all of them, it's primary use would be for data logging and for "scripting", that is reading in control information to change control parameters over time. It might be used to store maps for a roaming robot for example, basically relatively low speed, low volume data rates. The logs or "scripts" would be processed on a PC and the FAT file system would make this transferring simple. Bean's data logger is a great example of this kind of use. It's cheap, low power, simple to use, but a little too limited in capabilities. In particular, there's no capability to delete or overwrite an existing file. That's not something you normally want to do with a data logger, but there are other, more complex applications where that's vital.

The Propeller is a special case. You really have to think of this just like a PC. Although many applications will only need the same capabilities as a Stamp might, many will need a more general mass storage controller, intended for higher speeds, higher volumes of data, and more control, like random positioning within files and updating files in place.

The Vinculum can handle both of these and can provide support for an external keyboard, mouse, and simple printer besides. The main problem is that the Vinculum firmware is not designed for control by a processor. It puts out unsolicited status messages, not designed for parsing by a controller. You may have to add a helper uber-controller, just to filter this stuff out and provide a status register that you can interrogate. It's a shame that FTDI doesn't provide this kind of mode already. It really belongs in their firmware. If it weren't for that, their VDRIVE might be usable as is with a Stamp.

If you do develop such an uber-controller, I suggest that you not hide too much of the Vinculum's capability while simplifying its use.

Dennis,
No, there's no user code.