Learning About USB
The engineers first found USB Complete by Jan Axelson,1 which claims to tell “everything you need to develop custom USB peripherals.” The first half of this book explains USB, data transfers, and device identification (called enumeration). The second half addresses device hardware design using chipsets. The book content isn't an exact match for developing Linux USB device drivers, but it provides a great introduction to USB communications. Here's what the engineers learned:
The USB bus is asynchronous serial, with differential signaling.
USB is plug-and-play; the user doesn't configure memory addresses, I/O addresses, interrupts or direct memory access (DMA).
USB v1.1 supports a 12Mbps data rate.
USB v2.0, which is relatively ...
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