README.md

Cross USB

A USB library which works seamlessly across most native and WASM targets.

---

Note

Web USB only works in Chromium based browsers for now.

Note

Web USB has certain interaction requirements in browsers, along with requiring a Secure context. Please read more about this on the mdn web docs

Important

When compiling this crate on a WASM target, you must use either the rustflags RUSTFLAGS=--cfg=web_sys_unstable_apis or by passing the argument in a .cargo/config.toml file. Read more here: https://rustwasm.github.io/wasm-bindgen/web-sys/unstable-apis.html

Dependencies

For native USB, the crate utilizies nusb, a pure rust library similar to the very popular libusb. If you don't need WASM support, just using nusb is the way to go!

For WASM, this crate utilizes web-sys which gives access to browser API calls, and in this case is used to interact with WebUSB.

Example

To learn about how USB communciations work, check out USB in a NutShell.

use cross_usb::prelude::*;
use cross_usb::usb::{Recipient, ControlType, ControlIn};
use cross_usb::device_filter;

// Obtain a device descriptor using a DeviceFilter,
// in this case with its VendorID and ProductID
let filters = vec![
    device_filter!{vendor_id: 0x054c, product_id: 0x00c9}
];
let dev_descriptor = cross_usb::get_device(filters).await.expect("Failed to find device");

// Open the device that the descriptor is describing
let dev = dev_descriptor.open().await.expect("Failed to open device");

// Obtain an interface of the device
let interface = dev.open_interface(0).await.expect("Failed to open interface");

// Send a Control transfer to the device, obtaining
// the result and storing it in `result`
let result = interface.control_in(ControlIn {
        control_type: ControlType::Vendor,
        recipient: Recipient::Interface,
        request: 0x01,
        value: 0,
        index: 0,
        length: 4,
    })
    .await
    .expect("Sending control transfer failed");

Check out the documentation as well!

TODO

• Add choice for native backend between libusb wrapper and pure rust nusb
• Allow platform-specific operations if the user requires them
• Hot plug support... requires either using libusb as an optional backend or for nusb to implement it