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本节介绍一个麦克风应用，制作8段式音频频谱显示器。C的内部集成了一个微型麦克风可以采集声音信号，通过配置I2S就能进行数据通讯，所以如果你想使用麦克风采集音频信号的话可以参考以下程序的I2S配置。本例程需要安装一个快速傅里叶变换的Arduino库，此外作者开启了GCC编译器3级优化。实际测试中还存在问题，大概运行1个小时左右就死机，不过这个案例能帮助我们很好的理解内置麦克风的使用。
[mw_shl_code=arduino,true]#include "arduinoFFT.h"
arduinoFFT FFT = arduinoFFT();
#include <M5StickC.h>
#include <driver/i2s.h>
#pragma GCC optimize ("O3")
#define PIN_CLK 0
#define PIN_DATA 34
#define READ_LEN (2 * 1024)
uint8_t BUFFER[READ_LEN] = {0};
uint16_t oldx[160];
uint16_t oldy[160];
uint16_t *adcBuffer = NULL; // uint16_t *adcBuffer = NULL;
#define SAMPLES 512 // Must be a power of 2
#define SAMPLING_FREQUENCY 40000
struct eqBand {
const char *freqname;
uint16_t amplitude;
int peak;
int lastpeak;
uint16_t lastval;
unsigned long lastmeasured;
};
eqBand audiospectrum[8] = {
// Adjust the amplitude values to fit your microphone
// freqname,amplitude,peak,lastpeak,lastval,lastmeasured
{ ".1",1000, 0, 0, 0, 0},
{ ".2", 500, 0, 0, 0, 0},
{ ".5", 300, 0, 0, 0, 0},
{ "1" , 250, 0, 0, 0, 0},
{ "2" , 200, 0, 0, 0, 0},
{ "4" , 100, 0, 0, 0, 0},
{ "8" , 50, 0, 0, 0, 0},
{ "16" , 50, 0, 0, 0, 0}
};
unsigned int sampling_period_us;
unsigned long microseconds;
double vReal[SAMPLES];
double vImag[SAMPLES];
unsigned long newTime, oldTime;
uint16_t tft_width = 160;
uint16_t tft_height = 80;
uint8_t bands = 8;
uint8_t bands_width = floor( tft_width / bands );
uint8_t bands_pad = bands_width - 10;
uint16_t colormap[255];//color palette for the band meter(pre-fill in setup)
void i2sInit(){
i2s_config_t i2s_config = {
.mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX | I2S_MODE_PDM),
.sample_rate = 44100,
.bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT, //is fixed at 12bit,stereo,MSB
.channel_format = I2S_CHANNEL_FMT_ALL_RIGHT,
.communication_format = I2S_COMM_FORMAT_I2S,
.intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,
.dma_buf_count = 2,
.dma_buf_len = 128,
};
i2s_pin_config_t pin_config;
pin_config.bck_io_num = I2S_PIN_NO_CHANGE;
pin_config.ws_io_num = PIN_CLK;
pin_config.data_out_num = I2S_PIN_NO_CHANGE;
pin_config.data_in_num = PIN_DATA;
i2s_driver_install(I2S_NUM_0, &i2s_config, 0, NULL);
i2s_set_pin(I2S_NUM_0, &pin_config);
i2s_set_clk(I2S_NUM_0, 44100,I2S_BITS_PER_SAMPLE_16BIT,I2S_CHANNEL_MONO);
}
void mic_record_task (void* arg){
while(1){
i2s_read_bytes(I2S_NUM_0,(char*)BUFFER,READ_LEN,(100/portTICK_RATE_MS));
adcBuffer = (uint16_t *)BUFFER;
showSignal();
vTaskDelay(100 / portTICK_RATE_MS);
}
}
void setup() {
M5.begin();
M5.Lcd.setRotation(1);
M5.Lcd.fillScreen(BLACK);
M5.Lcd.setTextColor(BLUE);
M5.Lcd.setTextSize(1);
i2sInit();
xTaskCreatePinnedToCore(mic_record_task,"mic_record_task",2048,NULL,1,NULL,1);
sampling_period_us = round(1000000 * (1.0 / SAMPLING_FREQUENCY));
delay(2000);
for(uint8_t i=0;i<tft_height;i++) {
//colormap = M5.Lcd.color565(tft_height-i*.5,i*1.1,0); //RGB
colormap = M5.Lcd.color565(tft_height-i*4.4,i*2.5,0);//RGB:rev macsbug
}
for (byte band = 0; band <= 7; band++) {
M5.Lcd.setCursor(bands_width*band + 2, 0);
M5.Lcd.print(audiospectrum[band].freqname);
}
}
void showSignal(){
for (int i = 0; i < SAMPLES; i++) {
newTime = micros() - oldTime;
oldTime = newTime;
vReal = adcBuffer;
vImag = 0;
while (micros() < (newTime + sampling_period_us)){//do nothing to wait
}
}
FFT.Windowing(vReal, SAMPLES, FFT_WIN_TYP_HAMMING, FFT_FORWARD);
FFT.Compute(vReal, vImag, SAMPLES, FFT_FORWARD);
FFT.ComplexToMagnitude(vReal, vImag, SAMPLES);
for (int i = 2; i < (SAMPLES/2); i++){
// Don't use sample 0 and only first SAMPLES/2 are usable.
// Each array eleement represents a frequency and its value the amplitude.
if (vReal > 1500) { // Add a crude noise filter, 10 x amplitude or more
byte bandNum = getBand(i);
if(bandNum!=8) {
displayBand(bandNum, (int)vReal/audiospectrum[bandNum].amplitude);
}
}
}
long vnow = millis();
for (byte band = 0; band <= 7; band++) {
// auto decay every 50ms on low activity bands
if(vnow - audiospectrum[band].lastmeasured > 50) {
displayBand(band, audiospectrum[band].lastval>4 ? audiospectrum[band].lastval-4 : 0);
}
if (audiospectrum[band].peak > 0) {
audiospectrum[band].peak -= 2;
if(audiospectrum[band].peak<=0) {
audiospectrum[band].peak = 0;
}
}
// only draw if peak changed
if(audiospectrum[band].lastpeak != audiospectrum[band].peak) {
// delete last peak
M5.Lcd.drawFastHLine(bands_width*band,tft_height-audiospectrum[band].lastpeak,bands_pad,BLACK);
audiospectrum[band].lastpeak = audiospectrum[band].peak;
M5.Lcd.drawFastHLine(bands_width*band, tft_height-audiospectrum[band].peak,
bands_pad, colormap[tft_height-audiospectrum[band].peak]);
}
}
}
void displayBand(int band, int dsize){
uint16_t hpos = bands_width*band;
int dmax = 200;
if(dsize>tft_height-10) {
dsize = tft_height-10; // leave some hspace for text
}
if(dsize < audiospectrum[band].lastval) {
// lower value, delete some lines
M5.Lcd.fillRect(hpos, tft_height-audiospectrum[band].lastval,
bands_pad, audiospectrum[band].lastval - dsize,BLACK);
}
if (dsize > dmax) dsize = dmax;
for (int s = 0; s <= dsize; s=s+4){
M5.Lcd.drawFastHLine(hpos, tft_height-s, bands_pad, colormap[tft_height-s]);
}
if (dsize > audiospectrum[band].peak){audiospectrum[band].peak = dsize;}
audiospectrum[band].lastval = dsize;
audiospectrum[band].lastmeasured = millis();
}
byte getBand(int i) {
if (i<=2 ) return 0; // 125Hz
if (i >3 && i<=5 ) return 1; // 250Hz
if (i >5 && i<=7 ) return 2; // 500Hz
if (i >7 && i<=15 ) return 3; // 1000Hz
if (i >15 && i<=30 ) return 4; // 2000Hz
if (i >30 && i<=53 ) return 5; // 4000Hz
if (i >53 && i<=200 ) return 6; // 8000Hz
if (i >200 ) return 7; // 16000Hz
return 8;
}
void loop() {}[/mw_shl_code] |
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发表于 2019-10-28 10:12