mirror of https://github.com/ARMmbed/mbed-os.git
52 lines
1.2 KiB
C++
52 lines
1.2 KiB
C++
// Playback example with the USBAUDIO library
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#include "mbed.h"
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#include "USBAudio.h"
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// frequency: 48 kHz
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#define FREQ_SPK 16000
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#define FREQ_MIC 16000
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// 2channels: stereo
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#define NB_CHA_SPK 2
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#define NB_CHA_MIC 2
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// length computed: each ms, we receive 48 * 16bits ->48 * 2 bytes. as there are two channels, the length will be 48 * 2 * 2
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#define LENGTH_AUDIO_PACKET_SPK (FREQ_SPK / 500) * NB_CHA_SPK
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#define LENGTH_AUDIO_PACKET_MIC (FREQ_MIC / 500) * NB_CHA_MIC
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// USBAudio object
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USBAudio audio(FREQ_SPK, NB_CHA_SPK, FREQ_MIC, NB_CHA_MIC, 0xab45, 0x0378);
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int filled;
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int ready = 2;
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/* buffer 4 packets to avoid */
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int buf[4][LENGTH_AUDIO_PACKET_SPK/sizeof(int)];
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void tx_audio(void)
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{
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/* used some buffer in advance */
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ready = (filled+2)&0x3;
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audio.writeSync((uint8_t *)buf[ready]);
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}
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void rx_audio(void)
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{
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int size=0;
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int next = (filled + 1)&0x3;
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size = audio.readSync((uint8_t *)buf[next]);
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if (size ) filled = next;
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if ((size) && (size!=LENGTH_AUDIO_PACKET_MIC)) printf("%d\n",size);
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}
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int main()
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{
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filled = 0;
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memset(&buf[0][0], 0, sizeof (buf));
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audio.attachTx(tx_audio);
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audio.attachRx(rx_audio);
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/* start the tx with a silent packet */
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audio.write((uint8_t *)buf[2]);
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while(1);
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}
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