28.3.2.5 IN Transaction

When an IN token is detected and if the device address n of the token packet does not match that of the endpoint, the packet is discarded and the USB peripheral returns to idle, waiting for the next token packet.

When the address matches, the USB peripheral then fetches the Endpoint Status (EP[n].IN.STATUS) register and Endpoint Control (EP[n].IN.CTRL) register from the addressed output endpoint in the endpoint configuration table. If the endpoint is disabled, the USB peripheral returns to idle and waits for the next token packet.