Fix PDITarget_ReceiveByte() not discarding the start bit properly, and reading in...
[pub/USBasp.git] / Demos / Device / ClassDriver / AudioOutput / AudioOutput.c
index d7de7d5..3648b6e 100644 (file)
@@ -95,27 +95,20 @@ void ProcessNextSample(void)
                /* Clear the sample reload timer */\r
                TIFR0 |= (1 << OCF0A);\r
 \r
-               /* Retrieve the signed 16-bit left and right audio samples */\r
-               int16_t LeftSample_16Bit  = Audio_Device_ReadSample16(&Speaker_Audio_Interface);\r
-               int16_t RightSample_16Bit = Audio_Device_ReadSample16(&Speaker_Audio_Interface);\r
-\r
-               /* Massage signed 16-bit left and right audio samples into signed 8-bit */\r
-               int8_t  LeftSample_8Bit   = (LeftSample_16Bit  >> 8);\r
-               int8_t  RightSample_8Bit  = (RightSample_16Bit >> 8);\r
+               /* Retrieve the signed 16-bit left and right audio samples, convert to 8-bit */\r
+               int8_t  LeftSample_8Bit   = (Audio_Device_ReadSample16(&Speaker_Audio_Interface) >> 8);\r
+               int8_t  RightSample_8Bit  = (Audio_Device_ReadSample16(&Speaker_Audio_Interface) >> 8);\r
 \r
                /* Mix the two channels together to produce a mono, 8-bit sample */\r
                int8_t  MixedSample_8Bit  = (((int16_t)LeftSample_8Bit + (int16_t)RightSample_8Bit) >> 1);\r
 \r
-               /* Get absolute value of mixed sample value */\r
-               uint8_t MixedSample_8Bit_Abs = abs(MixedSample_8Bit);\r
-\r
 #if defined(AUDIO_OUT_MONO)\r
                /* Load the sample into the PWM timer channel */\r
-               OCR3A = ((uint8_t)MixedSample_8Bit ^ (1 << 7));\r
+               OCR3A = (MixedSample_8Bit ^ (1 << 7));\r
 #elif defined(AUDIO_OUT_STEREO)\r
                /* Load the dual 8-bit samples into the PWM timer channels */\r
-               OCR3A = ((uint8_t)LeftSample_8Bit  ^ (1 << 7));\r
-               OCR3B = ((uint8_t)RightSample_8Bit ^ (1 << 7));\r
+               OCR3A = (LeftSample_8Bit  ^ (1 << 7));\r
+               OCR3B = (RightSample_8Bit ^ (1 << 7));\r
 #elif defined(AUDIO_OUT_PORTC)\r
                /* Load the 8-bit mixed sample into PORTC */\r
                PORTC = MixedSample_8Bit;\r
@@ -123,17 +116,15 @@ void ProcessNextSample(void)
 \r
                uint8_t LEDMask = LEDS_NO_LEDS;\r
 \r
-               if (MixedSample_8Bit_Abs > 2)\r
-                 LEDMask |= LEDS_LED1;\r
-                 \r
-               if (MixedSample_8Bit_Abs > 4)\r
-                 LEDMask |= LEDS_LED2;\r
-                 \r
-               if (MixedSample_8Bit_Abs > 8)\r
-                 LEDMask |= LEDS_LED3;\r
-\r
-               if (MixedSample_8Bit_Abs > 16)\r
-                 LEDMask |= LEDS_LED4;\r
+               /* Turn on LEDs as the sample amplitude increases */\r
+               if (MixedSample_8Bit > 16)\r
+                 LEDMask = (LEDS_LED1 | LEDS_LED2 | LEDS_LED3 | LEDS_LED4);\r
+               else if (MixedSample_8Bit > 8)\r
+                 LEDMask = (LEDS_LED1 | LEDS_LED2 | LEDS_LED3);\r
+               else if (MixedSample_8Bit > 4)\r
+                 LEDMask = (LEDS_LED1 | LEDS_LED2);\r
+               else if (MixedSample_8Bit > 2)\r
+                 LEDMask = (LEDS_LED1);\r
 \r
                LEDs_SetAllLEDs(LEDMask);\r
        }\r
@@ -145,9 +136,9 @@ void EVENT_USB_Device_Connect(void)
        LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);\r
        \r
        /* Sample reload timer initialization */\r
-       OCR0A   = (F_CPU / AUDIO_SAMPLE_FREQUENCY) - 1;\r
+       OCR0A   = (F_CPU / 8 / AUDIO_SAMPLE_FREQUENCY) - 1;\r
        TCCR0A  = (1 << WGM01);  // CTC mode\r
-       TCCR0B  = (1 << CS00);   // Fcpu speed\r
+       TCCR0B  = (1 << CS01);   // Fcpu/8 speed\r
 \r
 #if defined(AUDIO_OUT_MONO)\r
        /* Set speaker as output */\r