Module imxrt_usbd::full_speed [−][src]
A full-speed i.MX RT USB driver, supporting the usb-device ecosystem
Usage
You’ll need this crate, the usb-device crate, and USB device class crates
to realize a complete USB device. Use this crate to create a BusAdapter,
which is then supplied to the usb-device device interface.
See the BusAdapter documentation for requirements and examples.
Design
This section talks about the full-speed driver design. It assumes that you’re familiar with the details of the i.MX RT USB peripheral. If you just want to use the driver, you can skip this section.
Packets and transfers
All i.MX RT USB drivers manage queue heads (QH), and transfer
descriptors (TD). For the full-speed driver, each (QH) is assigned
only one (TD) to perform I/O. We then assume each TD describes a single
packet. This is simple to implement, but it means that the full-speed
driver can only have one packet in flight per endpoint. You’re expected
to quickly respond to poll() outputs, and schedule the next transfer
in the time required for full-speed devices.
Structs
| BusAdapter | A |