AVR32 USB software framework for AUDIO

License

Use of this program is subject to Atmel's End User License Agreement.

Please read the Copyright notice at the bottom of this page.

Description

This embedded application source code illustrates how to implement a USB Audio stereo header microphone application on the AVR32 microcontroller. Refer to the "AVR32716: AVR UC3 USB Audio class" application note for more information about the USB audio class.

Using the application

Attached to a mini-B plug (ID pin unconnected) the application will be used in the device operating mode. Thus, the application can be connected to a system host (e.g. a PC) to operate as a USB Audio headset device.

The demonstration enumerates as a standard USB audio stereo headset with microphone. RAM audio buffer level is displayed in the buffer box (box empty= near underun, box full = near overrun). The frequency difference (in ppm) between the USB audio stream and the DAC (SSC/I2S or ABDAC) audio stream is displayed in the PPM box. Known issue: For the project AUDIO_EXAMPLE_ADAPTIF_SRC, the PPM box always display "0". CPU frequency (MHz) is displayed on the LCD in the CPU box. User control (play, pause, next, previous, volume up/down) is displayed in the HID box. The RAM status is also displayed on the LCD (data, bss, stack, total used heap, current used heap).

Architecture

As illustrated in the figure bellow, the application entry point is located is the audio_example.c file. The application run in a standalone mode. There is no need of an OS. In the standalone mode, the main function runs the usb_task, device_audio_task and device_hid_task tasks in an infinite loop.

The application is based on three different tasks:

arch_full.jpg

Architecture Overview

Main Files

Copyright notice

Copyright (c) 2009 Atmel Corporation. All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

3. The name of Atmel may not be used to endorse or promote products derived from this software without specific prior written permission.

4. This software may only be redistributed and used in connection with an Atmel AVR product.

THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE EXPRESSLY AND SPECIFICALLY DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE


Generated on Fri Feb 19 02:32:10 2010 for AVR32 - USB AUDIO Example by  doxygen 1.5.5