AT43USB370 datasheet(39/50 Pages) ATMEL

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AT43USB370

3340B–USB–12/03

Firmware

Architecture

The AT43USB370 firmware model is supported by a set of USB firmware embedded on-chip

and a set of system software with associated APIs running on the system processor. The APIs

are used to support the development of USB device drivers of any type.

The AT43USB37 requires the host firmware when running in the host mode, and the function

(or device) firmware when running in the function mode. The following sections describe in

detail the firmware architecture of the AT43USB370 host/function processor.

Host Firmware

The AT43USB370 host firmware consists of the Host USB Controller Driver (HUSBCD) and

Host System Interface Controller Driver (HSICD).

Host USB Controller

Driver (HUSBCD)

The HUSBCD runs on the USBC when the AT43USB370 operates in the host mode. This

driver performs the following tasks:

Autonomous Hub

Support

The HUSBCD embeds a complete Hub Class driver to provide an autonomous Hub support.

Device Enumeration

The HUSBCD enumerates the newly connected device or hub.

Frame Management

Frame management involves calculating the time required for the next transaction and trans-

action completion prediction as described in USB 2.0 Specifications. It also includes the

determinations the HUSBCD has to make at the time of enumeration to ensure that the

requirements of the newly connected device can be met within the current power and band-

width budget of the host.

Transaction Scheduling

The HUSBCD automatically schedules the transactions using the information that it receives

from the devices during enumeration. Isochronous and Interrupt transactions are given up to

90% of the frame time. Bulk and Control transfers are guaranteed at least 10% of the band-

width and are also allocated any available bandwidth not consumed by the Isochronous and

Interrupt transfers.

Bus Reclamation

The HUSBCD implements the Bus Reclamation mechanism that allows the AT43USB370

host to maximize the bus utilization by using all the time left after servicing pending transac-

tions to transfer bulk/control data.

Status Handling

After a transaction has been completed, the HUSBCD posts the transaction status to the

HSICD. The HUSBCD also enables and disables the concerned FIFOs for data and control

transfers.

Host System Interface

Controller Driver

(HSICD)

The HSICD runs on the System Interface Controller when the AT43USB370 is operating in the

host mode. This driver performs the following tasks:

Data Transfer

Management

The HSICD handles the data transfer between the USB function and the system processor

memory.

High Level API

Management

A set of C APIs and associated USB host system software library constitutes the basic build-

ing blocks of USB device drivers of any type. This USB host system software resides on the

system processor. The HSICD manages the information exchange between the embedded

AT43USB370 firmware stack and the host system software running on the system processor

through the host system interface APIs. For detailed descriptions of the APIs, refer to

AT43USB370 Software Development Guide.

AT43USB370 датащи(PDF) 39 Page - ATMEL Corporation

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