Datasheet

TUSB9261

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SLLSE67F –MARCH 2011–REVISED JULY 2013

4 OPERATION

4.1 General Functionality

The TUSB9261 ROM contains boot code that executes after a global reset which performs the initial

configuration required to load a firmware image from an attached SPI flash memory to local RAM.

Once the firmware is loaded it configures the SATA advanced host controller interface host bus adapter

(AHCI) and the USB device controller. In addition, the configuration of the AHCI includes a port reset

which initiates an out of band (OOB) TX sequence from the AHCI link layer to determine if a device is

connected, and if so negotiate the connection speed with the device (3.0 Gbps or 1.5 Gbps).

The configuration of the USB device controller includes creation of the descriptors, configuration of the

device endpoints for support of UASP and USB mass storage class bulk-only transport (BOT), allocation

of memory for the transmit request blocks (TRBs), and creation of the TRBs necessary to transmit and

receive packet data over the USB. In addition, the firmware provides any other custom configuration

required for application specific implementation, for example a HID interface for user initiated backup.

After USB device controller configuration is complete, if a SATA device was detected during the AHCI

configuration the firmware connects the device to the USB bus when VBUS is detected. According to the

USB 3.0 specification, the TUSB9261 will initially try to connect at SuperSpeed USB, if successful it will

enter U0; otherwise, after the training time out it will enable the DP pull up and connect as a USB 2.0

high-speed or full-speed device depending on the speed supported by host or hub port.

When connected, the firmware presents the BOT interface as the primary interface and the UASP

interface as the secondary interface. If the host stack is UASP aware, it can enable the UASP interface

using a SET_INTERFACE request for alternate interface 1.

Following speed negotiation, the device should transmit a device to host (D2H) FIS with the device

signature. This first D2H FIS is received by the link layer and copied to the port signature register. When

firmware is notified of the device connection it queries the device for capabilities using the IDENTIFY

DEVICE command. Firmware then configures the device as appropriate for its interface and features

supported, for example an HDD that supports native command queuing (NCQ).

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Product Folder Links: TUSB9261