WM8731 Example

Purpose

This example uses the Synchronous Serial Controller (SSC) of SAM devices to output an audio stream through the on-board WM8731 CODEC.

Requirements

This example can be used with SAM evaluation kits with the on-board WM8731 CODEC.

Description

This program plays a WAV file pre-loaded into the RAM. The audio stream is sent through the SSC interface connected to the on-board WM8731, enabling the sound to be audible using a pair of headphones.

Since the WM8731 DAC requires that it be feeded a master clock multiple of the sample rate, it is difficult to handle any WAV file. As such, this example application is limited to playing files with the following format:

• Format: WAV
• Sample rate: 48 kHz

The code can be roughly broken down as follows:

• Enable the clock.
• Configure and enable the Codec.
• Configure and enable the SSC interrupt.
• Load WAV file information.
• Play WAV file.

Usage

1. Build the program and download it into the evaluation board.
2. On the computer, open and configure a terminal application (e.g. HyperTerminal on Microsoft Windows) with these settings:
   • 115200 bauds
   • 8 bits of data
   • No parity
   • 1 stop bit
   • No flow control
3. Start the application.
4. In the terminal window, the following text should appear:

   -- WM8731 example xxx --
   -- SAMxx-xx
   -- Compiled: xxx xx xxxx xx:xx:xx --
   Menu :
   ------
   W: Play the WAV file loaded
   I: Display the information of the WAV file
   R: Receive WAV file with XMODEM Protocol
   S: Stop playback