diff options
Diffstat (limited to 'Demos/Device/LowLevel/AudioOutput/AudioOutput.c')
| -rw-r--r-- | Demos/Device/LowLevel/AudioOutput/AudioOutput.c | 87 |
1 files changed, 39 insertions, 48 deletions
diff --git a/Demos/Device/LowLevel/AudioOutput/AudioOutput.c b/Demos/Device/LowLevel/AudioOutput/AudioOutput.c index e33eb401e..cea44e25d 100644 --- a/Demos/Device/LowLevel/AudioOutput/AudioOutput.c +++ b/Demos/Device/LowLevel/AudioOutput/AudioOutput.c @@ -51,7 +51,6 @@ int main(void) for (;;) { - USB_Audio_Task(); USB_USBTask(); } } @@ -80,27 +79,28 @@ void EVENT_USB_Device_Connect(void) LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING); /* Sample reload timer initialization */ - OCR0A = (F_CPU / 8 / AUDIO_SAMPLE_FREQUENCY) - 1; - TCCR0A = (1 << WGM01); // CTC mode - TCCR0B = (1 << CS01); // Fcpu/8 speed + TIMSK0 = (1 << OCIE0A); + OCR0A = (F_CPU / 8 / AUDIO_SAMPLE_FREQUENCY) - 1; + TCCR0A = (1 << WGM01); // CTC mode + TCCR0B = (1 << CS01); // Fcpu/8 speed -#if defined(AUDIO_OUT_MONO) + #if defined(AUDIO_OUT_MONO) /* Set speaker as output */ - DDRC |= (1 << 6); -#elif defined(AUDIO_OUT_STEREO) + DDRC |= (1 << 6); + #elif defined(AUDIO_OUT_STEREO) /* Set speakers as outputs */ - DDRC |= ((1 << 6) | (1 << 5)); -#elif defined(AUDIO_OUT_PORTC) + DDRC |= ((1 << 6) | (1 << 5)); + #elif defined(AUDIO_OUT_PORTC) /* Set PORTC as outputs */ - DDRC |= 0xFF; -#endif + DDRC |= 0xFF; + #endif -#if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO)) + #if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO)) /* PWM speaker timer initialization */ - TCCR3A = ((1 << WGM30) | (1 << COM3A1) | (1 << COM3A0) - | (1 << COM3B1) | (1 << COM3B0)); // Set on match, clear on TOP - TCCR3B = ((1 << WGM32) | (1 << CS30)); // Fast 8-Bit PWM, F_CPU speed -#endif + TCCR3A = ((1 << WGM30) | (1 << COM3A1) | (1 << COM3A0) + | (1 << COM3B1) | (1 << COM3B0)); // Set on match, clear on TOP + TCCR3B = ((1 << WGM32) | (1 << CS30)); // Fast 8-Bit PWM, F_CPU speed + #endif } /** Event handler for the USB_Disconnect event. This indicates that the device is no longer connected to a host via @@ -110,20 +110,20 @@ void EVENT_USB_Device_Disconnect(void) { /* Stop the timers */ TCCR0B = 0; -#if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO)) + #if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO)) TCCR3B = 0; -#endif + #endif -#if defined(AUDIO_OUT_MONO) + #if defined(AUDIO_OUT_MONO) /* Set speaker as input to reduce current draw */ - DDRC &= ~(1 << 6); -#elif defined(AUDIO_OUT_STEREO) + DDRC &= ~(1 << 6); + #elif defined(AUDIO_OUT_STEREO) /* Set speakers as inputs to reduce current draw */ - DDRC &= ~((1 << 6) | (1 << 5)); -#elif defined(AUDIO_OUT_PORTC) + DDRC &= ~((1 << 6) | (1 << 5)); + #elif defined(AUDIO_OUT_PORTC) /* Set PORTC low */ - PORTC = 0x00; -#endif + PORTC = 0x00; + #endif /* Indicate streaming audio interface not selected */ StreamingAudioInterfaceSelected = false; @@ -171,34 +171,23 @@ void EVENT_USB_Device_UnhandledControlRequest(void) } } -/** Task to manage the Audio interface, reading in audio samples from the host, and outputting them to the speakers/LEDs as - * desired. - */ -void USB_Audio_Task(void) +/** ISR to handle the reloading of the PWM timer with the next sample. */ +ISR(TIMER0_COMPA_vect, ISR_BLOCK) { - /* Device must be connected and configured for the task to run */ - if (USB_DeviceState != DEVICE_STATE_Configured) - return; - - /* Check to see if the streaming interface is selected, if not the host is not receiving audio */ - if (!(StreamingAudioInterfaceSelected)) - return; + uint8_t PrevEndpoint = Endpoint_GetCurrentEndpoint(); /* Select the audio stream endpoint */ Endpoint_SelectEndpoint(AUDIO_STREAM_EPNUM); - /* Check if the current endpoint can be read from (contains a packet) and that the next sample should be read */ - if (Endpoint_IsOUTReceived() && (TIFR0 & (1 << OCF0A))) + /* Check if the current endpoint can be read from (contains a packet) and the host is sending data */ + if (Endpoint_IsOUTReceived() && StreamingAudioInterfaceSelected) { - /* Clear the sample reload timer */ - TIFR0 |= (1 << OCF0A); - /* Retrieve the signed 16-bit left and right audio samples, convert to 8-bit */ - int8_t LeftSample_8Bit = ((int16_t)Endpoint_Read_Word_LE() >> 8); - int8_t RightSample_8Bit = ((int16_t)Endpoint_Read_Word_LE() >> 8); + int8_t LeftSample_8Bit = ((int16_t)Endpoint_Read_Word_LE() >> 8); + int8_t RightSample_8Bit = ((int16_t)Endpoint_Read_Word_LE() >> 8); /* Mix the two channels together to produce a mono, 8-bit sample */ - int8_t MixedSample_8Bit = (((int16_t)LeftSample_8Bit + (int16_t)RightSample_8Bit) >> 1); + int8_t MixedSample_8Bit = (((int16_t)LeftSample_8Bit + (int16_t)RightSample_8Bit) >> 1); /* Check to see if the bank is now empty */ if (!(Endpoint_IsReadWriteAllowed())) @@ -207,17 +196,17 @@ void USB_Audio_Task(void) Endpoint_ClearOUT(); } -#if defined(AUDIO_OUT_MONO) + #if defined(AUDIO_OUT_MONO) /* Load the sample into the PWM timer channel */ OCR3A = (MixedSample_8Bit ^ (1 << 7)); -#elif defined(AUDIO_OUT_STEREO) + #elif defined(AUDIO_OUT_STEREO) /* Load the dual 8-bit samples into the PWM timer channels */ OCR3A = (LeftSample_8Bit ^ (1 << 7)); OCR3B = (RightSample_8Bit ^ (1 << 7)); -#elif defined(AUDIO_OUT_PORTC) + #elif defined(AUDIO_OUT_PORTC) /* Load the 8-bit mixed sample into PORTC */ PORTC = MixedSample_8Bit; -#endif + #endif uint8_t LEDMask = LEDS_NO_LEDS; @@ -233,5 +222,7 @@ void USB_Audio_Task(void) LEDs_SetAllLEDs(LEDMask); } + + Endpoint_SelectEndpoint(PrevEndpoint); } |