1.1.3 GENERIC AUDIO DRIVER CODEC Library

The interface to the Generic Codec Driver library is defined in the audio/driver/codec/Generic/drv_Generic.h header file. Any C language source (.c) file that uses the Generic Codec Driver library should include this header.

Library Source Files:

The Generic Codec Driver library source files are provided in the audio/driver/codec/Generic/src directory. This folder may contain optional files and alternate implementations. Please refer to Configuring the Library for instructions on how to select optional features and to Building the Library for instructions on how to build the library.

Example Applications:

This codec is not used directly by any demonstration applications. However the following applications could be looked at, to see how a codec such as the WM8904 or AK4954 is used:

• audio/apps/audio_tone

• audio/apps/microphone_loopback

This topic describes system initialization, implementations, and includes a system access code example.

This topic describes driver initialization and provides a code example.

Description

For the application to start using an instance of the module, it must call the DRV_Generic_Open function. The DRV_Generic_Open function provides a driver handle to the Generic Codec Driver instance for operations. If the driver is deinitialized using the function DRV_Generic_Deinitialize, the application must call the DRV_Generic_Open function again to set up the instance of the driver.

For the various options available for IO_INTENT, please refer to Data Types and Constants in the Library Interface section.

Example:

DRV_HANDLE handle; SYS_STATUS genericStatus;

genericStatus Status = DRV_Generic_Status(sysObjects.genericStatus DevObject); if (SYS_STATUS_READY == genericStatus) { // The driver can now be opened.

appData.genericClient.handle = DRV_Generic_Open

(DRV_Generic_INDEX_0, DRV_IO_INTENT_WRITE | DRV_IO_INTENT_EXCLUSIVE); if(appData.genericClient.handle != DRV_HANDLE_INVALID) {

appData.state = APP_STATE_Generic_SET_BUFFER_HANDLER; } else { SYS_DEBUG(0, "Find out what's wrong \r\n");

} } else { /* Generic Driver Is not ready */

}

This topic provides information on client operations.

Description

Client operations provide the API interface for control command and audio data transfer to the Generic Codec.

The following Generic Codec specific control command functions are provided:

• DRV_Generic_SamplingRateSet

• DRV_Generic_SamplingRateGet

• DRV_Generic_VolumeSet

• DRV_Generic_VolumeGet

• DRV_Generic_MuteOn

• DRV_Generic_MuteOff

These functions schedule a non-blocking control command transfer operation. These functions submit the control command request to the Generic Codec. These functions submit the control command request to I2C Driver transmit queue, the request is processed immediately if it is the first request, or processed when the previous request is complete.

DRV_Generic_BufferAddWrite, DRV_Generic_BufferAddRead, and DRV_Generic_BufferAddWriteRead are buffered data operation functions. These functions schedule non-blocking audio data transfer operations. These functions add the request to I2S Driver transmit or receive buffer queue depends on the request type, and are executed immediately if it is the first buffer, or executed later when the previous buffer is complete. The driver notifies the client with DRV_Generic_BUFFER_EVENT_COMPLETE, DRV_Generic_BUFFER_EVENT_ERROR, or DRV_Generic_BUFFER_EVENT_ABORT events.

The configuration of the I2S Driver Library is based on the file configurations.h, as generated by the MHC.

This header file contains the configuration selection for the I2S Driver Library. Based on the selections made, the I2S Driver Library may support the selected features. These configuration settings will apply to all instances of the I2S Driver Library.

This header can be placed anywhere; however, the path of this header needs to be present in the include search path for a successful build. Refer to the Applications Help section for more details.

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