@ -39,6 +39,9 @@
/** Flag to indicate if the streaming audio alternative interface has been selected by the host. */
static bool StreamingAudioInterfaceSelected = false ;
/** Current audio sampling frequency of the streaming audio endpoint. */
static uint32_t CurrentAudioSampleFrequency = 48000 ;
/** Main program entry point. This routine contains the overall program flow, including initial
* setup of all components and the main program loop .
@ -87,7 +90,7 @@ void EVENT_USB_Device_Connect(void)
/* Sample reload timer initialization */
TIMSK0 = ( 1 < < OCIE0A ) ;
OCR0A = ( ( F_CPU / 8 / AUDIO_SAMPLE_FREQUENCY ) - 1 ) ;
OCR0A = ( ( F_CPU / 8 / CurrentAudioSampleFrequency ) - 1 ) ;
TCCR0A = ( 1 < < WGM01 ) ; // CTC mode
TCCR0B = ( 1 < < CS01 ) ; // Fcpu/8 speed
}
@ -152,6 +155,57 @@ void EVENT_USB_Device_ControlRequest(void)
Endpoint_ClearSETUP ( ) ;
Endpoint_ClearStatusStage ( ) ;
}
break ;
case AUDIO_REQ_SetCurrent :
if ( USB_ControlRequest . bmRequestType = = ( REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_ENDPOINT ) )
{
/* Extract out the relevant request information to get the target Endpoint index and control being set */
uint8_t EndpointIndex = ( uint8_t ) USB_ControlRequest . wIndex ;
uint8_t EndpointControl = ( USB_ControlRequest . wValue > > 8 ) ;
/* Only handle SET CURRENT requests to the audio endpoint's sample frequency property */
if ( ( EndpointIndex = = AUDIO_STREAM_EPNUM ) & & ( EndpointControl = = AUDIO_EPCONTROL_SamplingFreq ) )
{
uint8_t SampleRate [ 3 ] ;
Endpoint_ClearSETUP ( ) ;
Endpoint_Read_Control_Stream_LE ( SampleRate , sizeof ( SampleRate ) ) ;
Endpoint_ClearOUT ( ) ;
/* Set the new sampling frequency to the value given by the host */
CurrentAudioSampleFrequency = ( ( ( uint32_t ) SampleRate [ 2 ] < < 16 ) | ( ( uint32_t ) SampleRate [ 1 ] < < 8 ) | ( uint32_t ) SampleRate [ 0 ] ) ;
/* Adjust sample reload timer to the new frequency */
OCR0A = ( ( F_CPU / 8 / CurrentAudioSampleFrequency ) - 1 ) ;
}
}
break ;
case AUDIO_REQ_GetCurrent :
if ( USB_ControlRequest . bmRequestType = = ( REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_ENDPOINT ) )
{
/* Extract out the relevant request information to get the target Endpoint index and control being retrieved */
uint8_t EndpointIndex = ( uint8_t ) USB_ControlRequest . wIndex ;
uint8_t EndpointControl = ( USB_ControlRequest . wValue > > 8 ) ;
/* Only handle GET CURRENT requests to the audio endpoint's sample frequency property */
if ( ( EndpointIndex = = AUDIO_STREAM_EPNUM ) & & ( EndpointControl = = AUDIO_EPCONTROL_SamplingFreq ) )
{
uint8_t SampleRate [ 3 ] ;
/* Convert the sampling rate value into the 24-bit format the host expects for the property */
SampleRate [ 2 ] = ( CurrentAudioSampleFrequency > > 16 ) ;
SampleRate [ 1 ] = ( CurrentAudioSampleFrequency > > 8 ) ;
SampleRate [ 0 ] = ( CurrentAudioSampleFrequency & 0xFF ) ;
Endpoint_ClearSETUP ( ) ;
Endpoint_Write_Control_Stream_LE ( SampleRate , sizeof ( SampleRate ) ) ;
Endpoint_ClearOUT ( ) ;
}
}
break ;
}
}
Dean Camera
13 years ago