Digital Voice Systems VC-20-ATC-10B Specifikace stáhnout pdf (Strana 45)

FAA20 Embedded NEXCOM Vocoder

Board Manual

This manual has been prepared for the Federal Aviation Administration.

FA100-00107 (March 2004) – Rev 1.0.0 Page 39

6.2 Software Architecture

The FAA20 hardware platform houses two different applications: the Boot

Application and the Main Application.

After reset the Boot Application is loaded from protected flash memory

using the built-in, ROM-based boot loader in the ‘C54 processor. This

program then loads and executes the Main Application. The ROM-based

boot loader only supports relatively small programs. The Boot Application

supports large programs loaded from multiple pages of flash memory. In

addition, this protected application supports the upgrade/reprogramming of

the Main Application. The FAA20 always has this core program that can be

used to reload main flash memory, as required.

The remainder of this section describes the FAA20 Main Application.

6.2.1 Software Block Diagram

The FAA20 software is built on the DSP/BIOS operating system. It utilizes

all three types of available interrupts: hardware (HWI), software (SWI), and

periodic (PRD). It has one major runtime task (TSK) that runs the

command processor. Thus, most of the normal operating functions are

executed in the interrupt environment.

Figure 20 is a software architecture diagram for the FAA20 main

application. Software threads (interrupts or tasks) are indicated with

rounded boxes. Queues are indicated with an open box (no sides).

Hardware devices that are external to the software are indicated with three-

dimensional (3D) boxes. Data communication between threads and

queues are indicated with solid black lines. Control flows are indicated with

red dotted lines.

From a functional standpoint, Figure 20 is divided into three major sections:

Linear Voice, Compressed Voice, and Command & Control. The functions

in the first two sections (the voice processing portion of software

architecture flow) are understandably similar to the voice processing flow

diagram (refer to Figure 9). These functions operate entirely in the

interrupt environment. The last section of the diagram shows the command

and control functions of the software. It contains the only runtime task in

the FAA20 software architecture, i.e., the Command Processor

(CMD_TSK).

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Digital Voice Systems VC-20-ATC-10B Specifikace Strana 45