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@ -51,7 +51,6 @@ int main(void)
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for (;;)
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{
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USB_Audio_Task();
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USB_USBTask();
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}
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}
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@ -80,27 +79,28 @@ void EVENT_USB_Device_Connect(void)
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LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
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/* Sample reload timer initialization */
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TIMSK0 = (1 << OCIE0A);
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OCR0A = (F_CPU / 8 / AUDIO_SAMPLE_FREQUENCY) - 1;
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TCCR0A = (1 << WGM01); // CTC mode
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TCCR0B = (1 << CS01); // Fcpu/8 speed
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#if defined(AUDIO_OUT_MONO)
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#if defined(AUDIO_OUT_MONO)
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/* Set speaker as output */
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DDRC |= (1 << 6);
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#elif defined(AUDIO_OUT_STEREO)
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#elif defined(AUDIO_OUT_STEREO)
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/* Set speakers as outputs */
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DDRC |= ((1 << 6) | (1 << 5));
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#elif defined(AUDIO_OUT_PORTC)
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#elif defined(AUDIO_OUT_PORTC)
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/* Set PORTC as outputs */
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DDRC |= 0xFF;
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#endif
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#endif
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#if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
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#if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
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/* PWM speaker timer initialization */
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TCCR3A = ((1 << WGM30) | (1 << COM3A1) | (1 << COM3A0)
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| (1 << COM3B1) | (1 << COM3B0)); // Set on match, clear on TOP
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TCCR3B = ((1 << WGM32) | (1 << CS30)); // Fast 8-Bit PWM, F_CPU speed
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#endif
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#endif
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}
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/** Event handler for the USB_Disconnect event. This indicates that the device is no longer connected to a host via
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@ -110,20 +110,20 @@ void EVENT_USB_Device_Disconnect(void)
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{
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/* Stop the timers */
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TCCR0B = 0;
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#if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
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#if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
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TCCR3B = 0;
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#endif
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#endif
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#if defined(AUDIO_OUT_MONO)
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#if defined(AUDIO_OUT_MONO)
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/* Set speaker as input to reduce current draw */
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DDRC &= ~(1 << 6);
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#elif defined(AUDIO_OUT_STEREO)
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#elif defined(AUDIO_OUT_STEREO)
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/* Set speakers as inputs to reduce current draw */
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DDRC &= ~((1 << 6) | (1 << 5));
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#elif defined(AUDIO_OUT_PORTC)
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#elif defined(AUDIO_OUT_PORTC)
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/* Set PORTC low */
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PORTC = 0x00;
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#endif
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#endif
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/* Indicate streaming audio interface not selected */
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StreamingAudioInterfaceSelected = false;
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@ -171,28 +171,17 @@ void EVENT_USB_Device_UnhandledControlRequest(void)
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}
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}
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/** Task to manage the Audio interface, reading in audio samples from the host, and outputting them to the speakers/LEDs as
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* desired.
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*/
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void USB_Audio_Task(void)
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/** ISR to handle the reloading of the PWM timer with the next sample. */
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ISR(TIMER0_COMPA_vect, ISR_BLOCK)
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{
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/* Device must be connected and configured for the task to run */
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if (USB_DeviceState != DEVICE_STATE_Configured)
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return;
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/* Check to see if the streaming interface is selected, if not the host is not receiving audio */
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if (!(StreamingAudioInterfaceSelected))
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return;
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uint8_t PrevEndpoint = Endpoint_GetCurrentEndpoint();
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/* Select the audio stream endpoint */
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Endpoint_SelectEndpoint(AUDIO_STREAM_EPNUM);
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/* Check if the current endpoint can be read from (contains a packet) and that the next sample should be read */
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if (Endpoint_IsOUTReceived() && (TIFR0 & (1 << OCF0A)))
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/* Check if the current endpoint can be read from (contains a packet) and the host is sending data */
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if (Endpoint_IsOUTReceived() && StreamingAudioInterfaceSelected)
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{
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/* Clear the sample reload timer */
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TIFR0 |= (1 << OCF0A);
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/* Retrieve the signed 16-bit left and right audio samples, convert to 8-bit */
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int8_t LeftSample_8Bit = ((int16_t)Endpoint_Read_Word_LE() >> 8);
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int8_t RightSample_8Bit = ((int16_t)Endpoint_Read_Word_LE() >> 8);
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@ -207,17 +196,17 @@ void USB_Audio_Task(void)
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Endpoint_ClearOUT();
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}
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#if defined(AUDIO_OUT_MONO)
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#if defined(AUDIO_OUT_MONO)
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/* Load the sample into the PWM timer channel */
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OCR3A = (MixedSample_8Bit ^ (1 << 7));
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#elif defined(AUDIO_OUT_STEREO)
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#elif defined(AUDIO_OUT_STEREO)
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/* Load the dual 8-bit samples into the PWM timer channels */
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OCR3A = (LeftSample_8Bit ^ (1 << 7));
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OCR3B = (RightSample_8Bit ^ (1 << 7));
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#elif defined(AUDIO_OUT_PORTC)
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#elif defined(AUDIO_OUT_PORTC)
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/* Load the 8-bit mixed sample into PORTC */
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PORTC = MixedSample_8Bit;
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#endif
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#endif
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uint8_t LEDMask = LEDS_NO_LEDS;
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@ -233,5 +222,7 @@ void USB_Audio_Task(void)
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LEDs_SetAllLEDs(LEDMask);
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}
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Endpoint_SelectEndpoint(PrevEndpoint);
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}
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