DreamCheeky USB Piano Keyboard
DreamCheeky USB Piano Keyboard
- Subject: DreamCheeky USB Piano Keyboard
- From: "Alex Brown" <email@hidden>
- Date: Tue, 19 Feb 2008 22:32:48 +0000
Hi,
For fun I'm writing a simple application for the DreamCheeky roll up
piano keyboard.
www.dreamcheeky.com
This keyboard is about as simple as it can be - 4 octaves of simple
touch keys with a USB cable stuck to one side - no aux controls, no
knobs, no speaker, no PSU.
The keyboard only comes with (crummy) windows support, so I thought
it would be interesting to write Mac support for it.
The keyboard presents as a HID tool that has an 8 byte bitfield
packet, trivially encoding the
I have combined HIDTestTool and PlaySoftMidi to provide a hit a key
/ play a note prototype, which works fine. I could continue along
these lines.
Now I want to do it a bit better, so I'm looking at the
SampleUSBMidiDriver to see if I make it work with other MIDI software
such as garageband.
However, after customising the SampleUSBMidiDriver with the vendor /
product and interface number, I discover that the call to
InterfaceOpen always returns kIOReturnExclusiveAccess.
I take this to mean that something already has this device open. If
so, it must be an internal something, because 1) it's not supported
officially and 2) I'm not running anything odd or anything that
responds to keypresses on the USB keyboard.
I know that these days you should use the HID interface for HID
devices, but the SampleUSBMidiDriver uses other USB interface
machinery (InterfaceInterface and such). I don't have the patience or
expertise to do the substantial rewrite the SampleISBMidiDriver to use
the new HID Interfaces. But HID devices are USB devices, so I expect
I can make it work.
So: does the SampleUSBMidiDriver assume that the devices it drives
are special midi devices, or use a special transport that is different
than HID devices, or can it in principle run with (e.g.) a standard
mouse or text keyboard?
Do HID devices get captured by the system in such a way that the HID
drivers can talk to them but the IOUSB always find them locked?
I'd appreciate any pointers people can give me.
-Alex Brown
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