Endpoint

Important

This module has been deprecated and moved to torii-usb, please see the migration guide.

Gateware Endpoint Interfaces

The SOL architecture separates gateware into two distinct groups: the core device, responsible for the low-level communications common to all devices, and endpoint interfaces, which perform high-level communications, and which are often responsible for tailoring each device for its intended application:

Every useful SOL device features at least one endpoint interface capable of at least handling enumeration. Many devices will provide multiple endpoint interfaces – often one for each endpoint – but this is not a requirement. Incoming token, data, and handshake packets are routed to all endpoint interfaces; it is up to each endpoint interface to decide which packets to respond to.

*Note: terms like "interface" are overloaded: the single term "interface" can refer both to hardware interfaces
and to the USB concept of an Interface. The "interface" in "endpoint interface" is an instance of the former;
they are conceptually distinct from USB interfaces. To reduce conflation, we'll use the full phrase "endpoint
interface" in this document.*

As a single endpoint interface may handle packets for multiple endpoints; it is entirely possible to have a device that talks on multiple endpoints, but which uses only one endpoint interface.

Exclusivity

A SOL USBDevice performs no arbitration – if two endpoint interfaces attempt to transmit at the same time, the result is undefined; and often will result in undesirable output. Accordingly, it’s important to ensure a “clear delineation of responsibility” across endpoint interfaces. This is often accomplished by ensuring only one endpoint interface handles a given endpoint or request type.