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@ -195,9 +195,12 @@ void USB_Audio_Task(void)
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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 */
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int16_t LeftSample_16Bit = (int16_t)Endpoint_Read_Word_LE();
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int16_t RightSample_16Bit = (int16_t)Endpoint_Read_Word_LE();
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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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/* Mix the two channels together to produce a mono, 8-bit sample */
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int8_t MixedSample_8Bit = (((int16_t)LeftSample_8Bit + (int16_t)RightSample_8Bit) >> 1);
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/* Check to see if the bank is now empty */
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if (!(Endpoint_IsReadWriteAllowed()))
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@ -206,23 +209,13 @@ void USB_Audio_Task(void)
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Endpoint_ClearOUT();
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}
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/* Massage signed 16-bit left and right audio samples into signed 8-bit */
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int8_t LeftSample_8Bit = (LeftSample_16Bit >> 8);
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int8_t RightSample_8Bit = (RightSample_16Bit >> 8);
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/* Mix the two channels together to produce a mono, 8-bit sample */
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int8_t MixedSample_8Bit = (((int16_t)LeftSample_8Bit + (int16_t)RightSample_8Bit) >> 1);
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/* Get absolute value of mixed sample value */
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uint8_t MixedSample_8Bit_Abs = abs(MixedSample_8Bit);
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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 = ((uint8_t)MixedSample_8Bit ^ (1 << 7));
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OCR3A = (MixedSample_8Bit ^ (1 << 7));
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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 = ((uint8_t)LeftSample_8Bit ^ (1 << 7));
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OCR3B = ((uint8_t)RightSample_8Bit ^ (1 << 7));
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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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/* Load the 8-bit mixed sample into PORTC */
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PORTC = MixedSample_8Bit;
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@ -231,15 +224,15 @@ void USB_Audio_Task(void)
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uint8_t LEDMask = LEDS_NO_LEDS;
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/* Turn on LEDs as the sample amplitude increases */
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if (MixedSample_8Bit_Abs > 16)
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if (MixedSample_8Bit > 16)
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LEDMask = (LEDS_LED1 | LEDS_LED2 | LEDS_LED3 | LEDS_LED4);
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else if (MixedSample_8Bit_Abs > 8)
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else if (MixedSample_8Bit > 8)
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LEDMask = (LEDS_LED1 | LEDS_LED2 | LEDS_LED3);
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else if (MixedSample_8Bit_Abs > 4)
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else if (MixedSample_8Bit > 4)
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LEDMask = (LEDS_LED1 | LEDS_LED2);
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else if (MixedSample_8Bit_Abs > 2)
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else if (MixedSample_8Bit > 2)
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LEDMask = (LEDS_LED1);
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LEDs_SetAllLEDs(LEDMask);
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}
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}
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