Intel® Agilex™ Hard Processor System Technical Reference Manual

ID 683567
Date 2/14/2023
Public

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18.6.3.2.2. OUT Transactions

For an OUT transaction, the application performs the following steps:

  1. Enables the endpoint
  2. Waits for the packet received interrupt from the USB OTG controller
  3. Retrieves the packet from the receive FIFO buffer

When an OUT token or PING token is received on an endpoint where the receive FIFO buffer does not have sufficient space, the controller performs the following steps:

  1. Generates an interrupt
  2. Returns a NAK handshake to USB host

If sufficient space is available, the controller stores the data in the receive FIFO buffer and returns an ACK handshake to the USB link.