Qiuyang Tao / Mbed 2 deprecated USB_speaker

USB Speak with Digital Volume Control

Dependencies:   AD5206 USBDevice mbed

Fork of USBAUDIO_speaker by Samuel Mokrani

main.cpp@11:d62d67b930f7, 2015-10-17 (annotated)

Committer:
taoqiuyang
Date:
Sat Oct 17 22:17:07 2015 +0000
Revision:
11:d62d67b930f7
Parent:
10:352d3dbfd6ec 
USB Speaker with Digital Volume Control

Who changed what in which revision?

UserRevisionLine numberNew contents of line
samux 3:41b10e311100 1 // USBAudio speaker example
samux 0:5176b3dfccd6 2
samux 0:5176b3dfccd6 3 #include "mbed.h"
samux 0:5176b3dfccd6 4 #include "USBAudio.h"
taoqiuyang 10:352d3dbfd6ec 5 #include "AD5206.h"
taoqiuyang 10:352d3dbfd6ec 6
taoqiuyang 10:352d3dbfd6ec 7 AD5206 digipot(p5, p6, p7,p8);
taoqiuyang 10:352d3dbfd6ec 8 int val=150;
taoqiuyang 10:352d3dbfd6ec 9 DigitalOut led1(LED1);
taoqiuyang 10:352d3dbfd6ec 10 DigitalOut led2(LED2);
taoqiuyang 10:352d3dbfd6ec 11 DigitalIn but1(p22);
taoqiuyang 10:352d3dbfd6ec 12 DigitalIn but2(p21);
taoqiuyang 10:352d3dbfd6ec 13
samux 0:5176b3dfccd6 14
samux 0:5176b3dfccd6 15 // frequency: 48 kHz
samux 0:5176b3dfccd6 16 #define FREQ 48000
samux 0:5176b3dfccd6 17
samux 0:5176b3dfccd6 18 // 1 channel: mono
samux 0:5176b3dfccd6 19 #define NB_CHA 1
samux 0:5176b3dfccd6 20
samux 0:5176b3dfccd6 21 // 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 2:c3edc567ae33 22 #define AUDIO_LENGTH_PACKET 48 * 2 * 1
samux 0:5176b3dfccd6 23
samux 7:ba4f65ce69f2 24 // USBAudio (we just use audio packets received, we don't send audio packets to the computer in this example)
samux 7:ba4f65ce69f2 25 USBAudio audio(FREQ, NB_CHA, 8000, 1, 0x7180, 0x7500);
samux 0:5176b3dfccd6 26
samux 0:5176b3dfccd6 27 // speaker connected to the AnalogOut output. The audio stream received over USb will be sent to the speaker
samux 0:5176b3dfccd6 28 AnalogOut speaker(p18);
samux 0:5176b3dfccd6 29
samux 0:5176b3dfccd6 30 // ticker to send data to the speaker at the good frequency
samux 0:5176b3dfccd6 31 Ticker tic;
taoqiuyang 10:352d3dbfd6ec 32 Ticker tic2;
taoqiuyang 10:352d3dbfd6ec 33
samux 0:5176b3dfccd6 34
samux 1:0335b5c18618 35 // buffer where will be store one audio packet (LENGTH_AUDIO_PACKET/2 because we are storing int16 and not uint8)
samux 2:c3edc567ae33 36 int16_t buf[AUDIO_LENGTH_PACKET/2];
samux 0:5176b3dfccd6 37
samux 0:5176b3dfccd6 38 // show if an audio packet is available
samux 0:5176b3dfccd6 39 volatile bool available = false;
samux 0:5176b3dfccd6 40
samux 0:5176b3dfccd6 41 // index of the value which will be send to the speaker
samux 0:5176b3dfccd6 42 int index_buf = 0;
samux 0:5176b3dfccd6 43
samux 0:5176b3dfccd6 44 // previous value sent to the speaker
samux 0:5176b3dfccd6 45 uint16_t p_val = 0;
samux 0:5176b3dfccd6 46
samux 0:5176b3dfccd6 47 // function executed each 1/FREQ s
samux 0:5176b3dfccd6 48 void tic_handler() {
samux 0:5176b3dfccd6 49 float speaker_value;
samux 0:5176b3dfccd6 50
samux 0:5176b3dfccd6 51 if (available) {
samux 0:5176b3dfccd6 52 //convert 2 bytes in float
samux 1:0335b5c18618 53 speaker_value = (float)(buf[index_buf]);
samux 0:5176b3dfccd6 54
samux 0:5176b3dfccd6 55 // speaker_value between 0 and 65535
samux 0:5176b3dfccd6 56 speaker_value += 32768.0;
samux 0:5176b3dfccd6 57
samux 0:5176b3dfccd6 58 // adjust according to current volume
samux 0:5176b3dfccd6 59 speaker_value *= audio.getVolume();
samux 0:5176b3dfccd6 60
samux 0:5176b3dfccd6 61 // as two bytes has been read, we move the index of two bytes
samux 1:0335b5c18618 62 index_buf++;
samux 0:5176b3dfccd6 63
samux 0:5176b3dfccd6 64 // if we have read all the buffer, no more data available
samux 2:c3edc567ae33 65 if (index_buf == AUDIO_LENGTH_PACKET/2) {
samux 0:5176b3dfccd6 66 index_buf = 0;
samux 0:5176b3dfccd6 67 available = false;
samux 0:5176b3dfccd6 68 }
samux 0:5176b3dfccd6 69 } else {
samux 0:5176b3dfccd6 70 speaker_value = p_val;
samux 0:5176b3dfccd6 71 }
samux 0:5176b3dfccd6 72
samux 0:5176b3dfccd6 73 p_val = speaker_value;
samux 0:5176b3dfccd6 74
samux 0:5176b3dfccd6 75 // send value to the speaker
samux 0:5176b3dfccd6 76 speaker.write_u16((uint16_t)speaker_value);
samux 0:5176b3dfccd6 77 }
samux 0:5176b3dfccd6 78
taoqiuyang 10:352d3dbfd6ec 79 void tic_handler2() {
taoqiuyang 10:352d3dbfd6ec 80 led1=0;
taoqiuyang 10:352d3dbfd6ec 81 led2=0;
taoqiuyang 10:352d3dbfd6ec 82 if (!but1){led1=1;val+=20;}
taoqiuyang 10:352d3dbfd6ec 83 if (!but2){led2=1;val-=20;}
taoqiuyang 10:352d3dbfd6ec 84 digipot.write_AD5206(0,val);
taoqiuyang 10:352d3dbfd6ec 85
taoqiuyang 10:352d3dbfd6ec 86 if (val>255){val=255;}
taoqiuyang 10:352d3dbfd6ec 87 if (val<0) {val=0;}
taoqiuyang 10:352d3dbfd6ec 88 }
taoqiuyang 10:352d3dbfd6ec 89
samux 0:5176b3dfccd6 90 int main() {
samux 0:5176b3dfccd6 91
samux 0:5176b3dfccd6 92 // attach a function executed each 1/FREQ s
samux 0:5176b3dfccd6 93 tic.attach_us(tic_handler, 1000000.0/(float)FREQ);
taoqiuyang 10:352d3dbfd6ec 94 tic2.attach(tic_handler2, 0.2);
taoqiuyang 10:352d3dbfd6ec 95
samux 0:5176b3dfccd6 96 while (1) {
samux 0:5176b3dfccd6 97 // read an audio packet
samux 1:0335b5c18618 98 audio.read((uint8_t *)buf);
samux 0:5176b3dfccd6 99 available = true;
samux 0:5176b3dfccd6 100 }
samux 0:5176b3dfccd6 101 }