43 lines
1.7 KiB
Plaintext
43 lines
1.7 KiB
Plaintext
As I dug my own way through the documentation of libusb 2.0 that ships
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with FreeBSD 8+ as the OS'es own USB library API, I noticed there are
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only few code examples around under /usr/src (namely, usbconfig
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itself).
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The libusb20(3) man page is a starting point, but it's a reference
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manual, nothing less, nothing more. Using just a reference, it's not
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very easy to start writing your own code based on that.
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So I started writing my own examples, to "get a feeling" about how to
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use the library. I covered two typical scenarios which are common for
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a number of devices.
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The first one is called "bulk", and uses bulk output (host to device)
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and input transfers to talk to an USB device.
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The second one is called "control", and can use both control output
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and input transfers, as well as so-called interrupt transfers. The
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latter are used for data that are being reported frequently or
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repeatedly, like position updates from a pointing device (mouse).
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Despite of its name, the host has to poll devices for their interrupt
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transfers on each USB frame (i.e., each 1 ms).
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Recommended reading is the USB 3.0 specification (the older 2.0 one
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would do as well), to be found under
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http://www.usb.org/developers/docs/
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as well as documents for individual USB device classes where
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appropriate.
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Feel free to be liberal in the licensing of these examples: while the
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beer-ware license mandates to keep the license notice, this only
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applies to modifications of the original examples itself. For
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copy&pasting (even a larger) piece of an example into your own work, I
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won't imply you have to reproduce the beer-ware license text there.
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Feel free to credit my name in your derived work if you want.
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Dresden, July 2012
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Joerg Wunsch <joerg@FreeBSD.org>
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# $FreeBSD$
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