1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
|
/*
LUFA Library
Copyright (C) Dean Camera, 2009.
dean [at] fourwalledcubicle [dot] com
www.fourwalledcubicle.com
*/
/*
Copyright 2009 Dean Camera (dean [at] fourwalledcubicle [dot] com)
Permission to use, copy, modify, and distribute this software
and its documentation for any purpose and without fee is hereby
granted, provided that the above copyright notice appear in all
copies and that both that the copyright notice and this
permission notice and warranty disclaimer appear in supporting
documentation, and that the name of the author not be used in
advertising or publicity pertaining to distribution of the
software without specific, written prior permission.
The author disclaim all warranties with regard to this
software, including all implied warranties of merchantability
and fitness. In no event shall the author be liable for any
special, indirect or consequential damages or any damages
whatsoever resulting from loss of use, data or profits, whether
in an action of contract, negligence or other tortious action,
arising out of or in connection with the use or performance of
this software.
*/
#include "AudioOutput.h"
USB_ClassInfo_Audio_t Speaker_Audio_Interface =
{
.InterfaceNumber = 0,
.DataOUTEndpointNumber = AUDIO_STREAM_EPNUM,
.DataOUTEndpointSize = AUDIO_STREAM_EPSIZE,
};
int main(void)
{
SetupHardware();
LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
for (;;)
{
if (Speaker_Audio_Interface.InterfaceEnabled)
ProcessNextSample();
USB_USBTask();
}
}
void SetupHardware(void)
{
/* Disable watchdog if enabled by bootloader/fuses */
MCUSR &= ~(1 << WDRF);
wdt_disable();
/* Disable clock division */
clock_prescale_set(clock_div_1);
/* Hardware Initialization */
LEDs_Init();
USB_Init();
}
void ProcessNextSample(void)
{
if ((TIFR0 & (1 << OCF0A)) && USB_Audio_IsSampleReceived(&Speaker_Audio_Interface))
{
/* Clear the sample reload timer */
TIFR0 |= (1 << OCF0A);
/* Retrieve the signed 16-bit left and right audio samples */
int16_t LeftSample_16Bit = (int16_t)USB_Audio_ReadSample16();
int16_t RightSample_16Bit = (int16_t)USB_Audio_ReadSample16();
/* Massage signed 16-bit left and right audio samples into signed 8-bit */
int8_t LeftSample_8Bit = (LeftSample_16Bit >> 8);
int8_t RightSample_8Bit = (RightSample_16Bit >> 8);
#if defined(AUDIO_OUT_MONO)
/* 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);
/* Load the sample into the PWM timer channel */
OCRxA = ((uint8_t)MixedSample_8Bit ^ (1 << 7));
#elif defined(AUDIO_OUT_STEREO)
/* Load the dual 8-bit samples into the PWM timer channels */
OCRxA = ((uint8_t)LeftSample_8Bit ^ (1 << 7));
OCRxB = ((uint8_t)RightSample_8Bit ^ (1 << 7));
#elif defined(AUDIO_OUT_PORTC)
/* 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);
PORTC = MixedSample_8Bit;
#else
uint8_t LEDMask = LEDS_NO_LEDS;
/* Make left channel positive (absolute) */
if (LeftSample_8Bit < 0)
LeftSample_8Bit = -LeftSample_8Bit;
/* Make right channel positive (absolute) */
if (RightSample_8Bit < 0)
RightSample_8Bit = -RightSample_8Bit;
/* Set first LED based on sample value */
if (LeftSample_8Bit < ((128 / 8) * 1))
LEDMask |= LEDS_LED2;
else if (LeftSample_8Bit < ((128 / 8) * 3))
LEDMask |= (LEDS_LED1 | LEDS_LED2);
else
LEDMask |= LEDS_LED1;
/* Set second LED based on sample value */
if (RightSample_8Bit < ((128 / 8) * 1))
LEDMask |= LEDS_LED4;
else if (RightSample_8Bit < ((128 / 8) * 3))
LEDMask |= (LEDS_LED3 | LEDS_LED4);
else
LEDMask |= LEDS_LED3;
LEDs_SetAllLEDs(LEDMask);
#endif
}
}
void EVENT_USB_Connect(void)
{
LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
/* Sample reload timer initialization */
OCR0A = (F_CPU / AUDIO_SAMPLE_FREQUENCY) - 1;
TCCR0A = (1 << WGM01); // CTC mode
TCCR0B = (1 << CS00); // Fcpu speed
#if defined(AUDIO_OUT_MONO)
/* Set speaker as output */
DDRC |= (1 << 6);
#elif defined(AUDIO_OUT_STEREO)
/* Set speakers as outputs */
DDRC |= ((1 << 6) | (1 << 5));
#elif defined(AUDIO_OUT_PORTC)
/* Set PORTC as outputs */
DDRC |= 0xFF;
#endif
#if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
/* PWM speaker timer initialization */
TCCRxA = ((1 << WGMx0) | (1 << COMxA1) | (1 << COMxA0)
| (1 << COMxB1) | (1 << COMxB0)); // Set on match, clear on TOP
TCCRxB = ((1 << WGMx2) | (1 << CSx0)); // Fast 8-Bit PWM, Fcpu speed
#endif
}
/** Event handler for the USB_Disconnect event. This indicates that the device is no longer connected to a host via
* the status LEDs, disables the sample update and PWM output timers and stops the USB and Audio management tasks.
*/
void EVENT_USB_Disconnect(void)
{
LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
/* Stop the timers */
TCCR0B = 0;
#if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
TCCRxB = 0;
#endif
#if defined(AUDIO_OUT_MONO)
/* Set speaker as input to reduce current draw */
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)
/* Set PORTC low */
PORTC = 0x00;
#endif
}
void EVENT_USB_ConfigurationChanged(void)
{
LEDs_SetAllLEDs(LEDMASK_USB_READY);
if (!(USB_Audio_ConfigureEndpoints(&Speaker_Audio_Interface)))
LEDs_SetAllLEDs(LEDMASK_USB_ERROR);
}
void EVENT_USB_UnhandledControlPacket(void)
{
USB_Audio_ProcessControlPacket(&Speaker_Audio_Interface);
}
|
