[sdiy] Taking the USB plunge...

[John Speth]

>     At my job (if you can call that...I guess I should be greatful I
> have one for the time being), my current project is involving 
> the use of
> a USB interface...So, I ordered a EZ-USB from Cypress.  This 
> thing seems
> to fit the bill for what I need to do at work...also, it seems to fit
> the bill as a substitute for a Midi interface...I might have to think
> about trying to use one of these to make a USB-> CV converter...

We use the EZUSB at work too.  IMO, it's a better alternative to FTDI for
more than one-off designs if you are constrained to a UART interface between
the USB engine and your device.  

Now host side the driver (required) is another kettle of fish.  After
climbing the learning curve on MS tools and techniques, driver design and
debug is a ton of work.  Cypress provides a short cut: You can obtain a USB
to serial driver from them.  It makes your USB look like a COM port.  I'm
sure someone with the right background can make it look like a MIDI port.
There might even be a worthwhile commercial opportunity in that.

I can see two problems with USB as the channel for MIDI: First is the lack
of ground isolation.  Second is the fact that USB peripherals are
essentially polled at 1ms intervals (best case).  Polling has potentially
big problems in a realtime interface.  Dig deeper and you need to consider
the possibility of data loss (bulk vs. isochronous) which is not acceptable
in MIDI.

Then you gotta buy a VID from the USB cops...

John Speth
mailto:johns at molectron.com 

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