Samuel Mokrani / Mbed 2 deprecated USBAudio_micro

USBAudio example using a microphone

Dependencies:   USBDevice mbed

main.cpp@6:be128039be16, 2011-12-20 (annotated)

Committer:
samux
Date:
Tue Dec 20 11:17:33 2011 +0000
Revision:
6:be128039be16
Parent:
5:b49b6a8ca111
Child:
7:6b0012b8fd01
works for m0 and m3 with cleaning up

Who changed what in which revision?

UserRevisionLine numberNew contents of line
samux 0:539ec61e1fbb 1 #include "mbed.h"
samux 0:539ec61e1fbb 2 #include "USBAudio.h"
samux 0:539ec61e1fbb 3
samux 6:be128039be16 4 extern "C" void HardFault_Handler() {
samux 6:be128039be16 5 error("Hard Fault!\n");
samux 6:be128039be16 6 }
samux 6:be128039be16 7
samux 5:b49b6a8ca111 8 // frequency: 8 kHz
samux 5:b49b6a8ca111 9 #define FREQ 8000
samux 5:b49b6a8ca111 10
samux 5:b49b6a8ca111 11 // 1 channel: mono
samux 5:b49b6a8ca111 12 #define NB_CHA 1
samux 0:539ec61e1fbb 13
samux 5:b49b6a8ca111 14 // length of an audio packet: each ms, we receive 48 * 16bits ->48 * 2 bytes. as there is one channel, the length will be 48 * 2 * 1
samux 5:b49b6a8ca111 15 #define AUDIO_LENGTH_PACKET (FREQ/500) * NB_CHA
samux 5:b49b6a8ca111 16
samux 6:be128039be16 17 USBAudio audio(FREQ, NB_CHA, 0x1111, 0x78ab);
samux 6:be128039be16 18
samux 3:e6a29c83ac52 19 AnalogIn mic(p20);
samux 5:b49b6a8ca111 20 DigitalOut p(p19);
samux 0:539ec61e1fbb 21
samux 5:b49b6a8ca111 22 int16_t buf[AUDIO_LENGTH_PACKET/2];
samux 4:bef3b485f22e 23
samux 0:539ec61e1fbb 24 int main() {
samux 6:be128039be16 25
samux 5:b49b6a8ca111 26 double mic_mean = 0.0;
samux 5:b49b6a8ca111 27 double mic_value;
samux 5:b49b6a8ca111 28
samux 5:b49b6a8ca111 29 // compute average value of the microphone. We can then center the audio signal sent to the computer
samux 5:b49b6a8ca111 30 for (int j = 0; j < 1000; j++) {
samux 5:b49b6a8ca111 31 mic_value = (mic.read_u16() >> 3);
samux 5:b49b6a8ca111 32 mic_mean = (mic_mean*j + mic_value)/(j+1);
samux 5:b49b6a8ca111 33 }
samux 3:e6a29c83ac52 34
samux 0:539ec61e1fbb 35 while (1) {
samux 6:be128039be16 36 p = 1;
samux 5:b49b6a8ca111 37 for (int i = 0; i < AUDIO_LENGTH_PACKET/2; i++) {
samux 5:b49b6a8ca111 38 buf[i] = (mic.read_u16() >> 3) - mic_mean;
samux 5:b49b6a8ca111 39 if (i != AUDIO_LENGTH_PACKET/2) {
samux 6:be128039be16 40 wait_us(80);
samux 3:e6a29c83ac52 41 }
samux 3:e6a29c83ac52 42 }
samux 6:be128039be16 43 p = 0;
samux 0:539ec61e1fbb 44 audio.write((uint8_t *)buf);
samux 0:539ec61e1fbb 45 }
samux 0:539ec61e1fbb 46 }