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vany5921 发表于 2020-7-18 14:57

M5Stack Fire的录音使用

       单通道录音，使用硬件定时器与中断进行采样，通过DAC进行播放
#include <M5Stack.h>
#include <atomic> /* https://baptiste-wicht.com/posts/2012/07/c11-concurrency-tutorial-part-4-atomic-type.html */

#define MICROPHONE 34
#define SPEAKER 25
#define BACKLIGHT 32
#define BUFFER_SIZE 4*1000*1000
#define SAMPLING_FREQUENCY 48000

#define LOWNOISE true /* set to false to enable backlight dimming */

TFT_eSPI tft = TFT_eSPI();

// set log level to debug for output
void logMemory() {
log_d("Used PSRAM: %d from: %d", ESP.getPsramSize() - ESP.getFreePsram(), ESP.getPsramSize() );
}

int8_t* sampleBuffer;
uint32_t allocatedSamples;
std::atomic<std::uint32_t> currentSample{0};
static hw_timer_t * sampleTimer{NULL}; /* only one timer is (re)used for both sampling and playback */
unsigned int sampling_period_us = round( 1000000 * ( 1.0 / SAMPLING_FREQUENCY ) );

static void IRAM_ATTR _sampleISR() {
uint32_t pos = currentSample.load();
if ( pos > BUFFER_SIZE - 1 ) {
timerEnd( sampleTimer );
sampleTimer = NULL;
return;
}
sampleBuffer = analogRead( MICROPHONE ) >> 4;
currentSample++;
}

bool startSampler() {
if ( NULL != sampleTimer ) return false;
delay(170); /* to not record the click from releasing the button */
currentSample.store( 0, std::memory_order_relaxed );
sampleTimer = timerBegin( 0, 80, true );
timerAttachInterrupt( sampleTimer, &_sampleISR, true );
timerAlarmWrite( sampleTimer, sampling_period_us, true );
timerAlarmEnable( sampleTimer );
return true;
}

void setup() {
pinMode( MICROPHONE, INPUT );
pinMode( SPEAKER, OUTPUT );
logMemory();

tft.init();
tft.setRotation( 1 );
tft.fillScreen( TFT_BLACK );
tft.setTextSize( 2 );
tft.drawString( "M5-Stack voicerecorder", 10, 5, 2 );

if ( LOWNOISE ) {
pinMode( BACKLIGHT, OUTPUT );
digitalWrite( BACKLIGHT, HIGH ); // This gives the least noise
} else {
ledcAttachPin( BACKLIGHT, 0);
ledcSetup( 0, 1300, 16 );
ledcWrite( 0, 0xFFFF / 16 ); // Dimming the BACKLIGHT will produce more base noise
}

if ( !ESP.getPsramSize() ) {
tft.setCursor( 55, 40 );
tft.print( "NO PSRAM FOUND!" );
while ( 1 ) delay( 100 );
}


sampleBuffer = (int8_t*)ps_malloc( BUFFER_SIZE * sizeof( int8_t ) );

tft.setCursor( 15, 40 );
tft.printf( "%3.1fkHz %5.1fkB %6.2fs", SAMPLING_FREQUENCY / 1000.0, ( BUFFER_SIZE * sizeof( int8_t ) ) / 1000.0, BUFFER_SIZE / (float)SAMPLING_FREQUENCY );
tft.drawString( "REC", 45, 200, 2 );
tft.drawString( "PLAY", 130, 200, 2 );
tft.drawString( "STOP", 220, 200, 2 );
}

void loop() {
M5.update();
if ( !sampleTimer && M5.BtnA.pressedFor( 5 ) ) startSampler();
if ( !sampleTimer && M5.BtnB.pressedFor( 5 ) ) startPlayback();
uint32_t pos = currentSample.load();
tft.setCursor( 85, 100 );
tft.printf( "%3i%% %6.2fs", map( pos, 0, BUFFER_SIZE - 1, 0, 100 ), pos / (float)SAMPLING_FREQUENCY );
tft.setCursor( 60, 130 );
tft.printf( " %7i/%7i", pos, BUFFER_SIZE );
if ( sampleTimer && M5.BtnC.pressedFor( 2 ) ) {
timerAlarmDisable( sampleTimer );
timerEnd( sampleTimer );
sampleTimer = NULL;
dacWrite( SPEAKER, 0 );
}
delay(10);
}

void IRAM_ATTR _playThroughDAC_ISR() {
uint32_t pos = currentSample.load();
if ( pos > BUFFER_SIZE - 1 ) {
timerEnd( sampleTimer );
sampleTimer = NULL;
dacWrite( SPEAKER, 0 );
return;
}
dacWrite( SPEAKER, sampleBuffer );
currentSample++;
}

bool startPlayback() {
if ( NULL != sampleTimer ) return false;
currentSample.store( 0, std::memory_order_relaxed );
sampleTimer = timerBegin( 0, 80, true );
timerAttachInterrupt( sampleTimer, &_playThroughDAC_ISR, true );
timerAlarmWrite( sampleTimer, sampling_period_us, true );
timerAlarmEnable( sampleTimer );
return true;
}

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