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Changed AudioInput and AudioOutput demos to reload the next sample via an interrupt rather than polling the sample timer.

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This commit is contained in:
Dean Camera 2010-10-26 06:52:09 +00:00
parent 55538dcef3
commit 08de757811
10 changed files with 88 additions and 112 deletions
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18
Demos/Device/ClassDriver/AudioInput/AudioInput.c
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@ -63,8 +63,6 @@ int main(void)
for (;;)
{
ProcessNextSample();
Audio_Device_USBTask(&Microphone_Audio_Interface);
USB_USBTask();
}
@ -91,17 +89,14 @@ void SetupHardware(void)
ADC_StartReading(ADC_REFERENCE_AVCC | ADC_RIGHT_ADJUSTED | MIC_IN_ADC_MUX_MASK);
}
/** Processes the next audio sample by reading the last ADC conversion and writing it to the audio
* interface, each time the sample reload timer period elapses to give a constant sample rate.
*/
void ProcessNextSample(void)
/** ISR to handle the reloading of the data endpoint with the next sample. */
ISR(TIMER0_COMPA_vect, ISR_BLOCK)
{
uint8_t PrevEndpoint = Endpoint_GetCurrentEndpoint();
/* Check if the sample reload timer period has elapsed, and that the USB bus is ready for a new sample */
if ((TIFR0 & (1 << OCF0A)) && Audio_Device_IsReadyForNextSample(&Microphone_Audio_Interface))
if (Audio_Device_IsReadyForNextSample(&Microphone_Audio_Interface))
{
/* Clear the sample reload timer compare flag, ready for the next interval */
TIFR0 |= (1 << OCF0A);
int16_t AudioSample;
#if defined(USE_TEST_TONE)
@ -126,6 +121,8 @@ void ProcessNextSample(void)
Audio_Device_WriteSample16(&Microphone_Audio_Interface, AudioSample);
}
Endpoint_SelectEndpoint(PrevEndpoint);
}
/** Event handler for the library USB Connection event. */
@ -134,6 +131,7 @@ void EVENT_USB_Device_Connect(void)
LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
/* Sample reload timer initialization */
TIMSK0 = (1 << OCIE0A);
OCR0A = (F_CPU / 8 / AUDIO_SAMPLE_FREQUENCY) - 1;
TCCR0A = (1 << WGM01); // CTC mode
TCCR0B = (1 << CS01); // Fcpu/8 speed

1
Demos/Device/ClassDriver/AudioInput/AudioInput.h
View file

@ -77,7 +77,6 @@
/* Function Prototypes: */
void SetupHardware(void);
void ProcessNextSample(void);
void EVENT_USB_Device_Connect(void);
void EVENT_USB_Device_Disconnect(void);