TUSB3410 datasheet(71/92 Pages) TI

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11–1

11 TUSB3410 Bootcode Flow

11.1 Introduction

TUSB3410 bootcode is a program embedded within TUSB3410 device. This program is designed to load application

firmware from either external memory device or USB host bootloader device driver. After finished downloading,

bootcode releases its control to the application firmware.

This document describes how the bootcode initializes the TUSB3410 device in detail. In addition, the default USB

descriptor, I2C device header format, USB host driver firmware downloading format, and supported built-in USB

vendor specific requests are listed for reference. Users should carefully follow the appropriate format to interface with

the bootcode. All unsupported formats might cause unexpected results.

The bootcode source code is also provided for programming reference.

11.2 Bootcode Programming Flow

After power-on reset, the bootcode initializes the I2C and USB registers along with internal variables. The bootcode

then checks to see if the I2C device contains a valid signature. If the I2C device has a valid signature, the bootcode

continues searching for descriptor blocks and then processes them if the checksum is correct. If application firmware

was found, the bootcode downloads it and releases the control to the application firmware. Otherwise, the bootcode

connects to the USB and waits for host driver to download application firmware. Once firmware downloading is

finished, the bootcode releases the control to the firmware.

The following is the bootcode step-by-step operation.

•

Check if bootcode is in the application mode. If the bootcode is in the application mode, the bootcode

releases the control to the application firmware. Otherwise, the bootcode continues.

•

Initialize all the default settings.

–

Call CopyDefaultSettings() routine.

Set I2C to 400-kHz speed.

–

Call UsbDataInitialization() routine.

Set bFUNADR = 0

Disconnect from USB (bUSBCTL = 0x00)

Bootcode handles USB reset

Copy predefined device, configuration, and string descriptors to RAM

Disable all endpoints and enable USB interrupt(SETUP, RSTR, SUSPR, and RESU)

•

Search for product signature

–

Check if valid signature is in I2C. If not, skip I2C process.

Read 2 bytes from address 0x0000 with type III and device address 0. Stop searching if valid

signature is found.

Read 2 bytes from address 0x0000 with type II and device address 4. Stop searching if valid

signature is found.

•

Load customized device, configuration and string descriptors from I2C EEPROM.

–

Process each descriptor block from I2C until end of header is found

If descriptor block is device, configuration or string descriptors, the bootcode overwrites the default

descriptors.

If descriptor block is binary firmware, the bootcode makes a note and loads the firmware later on.

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