I2S Support

[4refr0nt]

Now, we know how work I2S on ESP8266
https://github.com/espressif/esp8266_mp3_decoder/blob/master/mp3/include/i2s_reg.h

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[alecapu]

I've a test app that use I2S TX and RX in loopback using the ESP8266 SDK...
I'm try to migrate it to Arduino, but I've some problem with interrupt calls. Can some one help me ?

[torntrousers]

I'd really love to have I2S from the ESP/Arduino code to play saved audio/sounds. Here's a naive attempt that makes some buzzes and whistles so shows it compiles and runs, if nothing else maybe it might prompt someone who knows what they're doing to write an example that works ...

(I connect an 8ohm headphone directly to gpio3 (i2s output) and its quiet but easily audible. The mp3 demo says thats probably not advisable but it hasn't broken anything for me.)

Also, sketch uploads fail while the headphone is connected to gpio3 so need to disconnected to upload.

#include <ESP8266WiFi.h>
#include <i2s.h>
#include <i2s_reg.h>

void setup() {
   Serial.begin(115200); Serial.println();
   Serial.println("setup");

   // don't know if WiFi interupts will interfere with the i2s timing so for now switch it off
   Serial.println("WiFi off");
   WiFi.disconnect(true);
   delay(2000);

   // need to do something like i2sInit like i2s_freertos.c at: https://github.com/espressif/ESP8266_MP3_DECODER/blob/master/mp3/driver/i2s_freertos.c
   // i2sInit(); 
   // init doc in ESP I2S Module Description, looks a bit complicated, see http://bbs.espressif.com/download/file.php?id=658

//   i2c_writeReg_Mask_def(i2c_bbpll, i2c_bbpll_en_audio_clock_out, 1);

}

void loop() {
   Serial.println("loop");
   playIt();
   delay(5000);   
}

void playIt() {
   Serial.println("i2s begin");
   i2s_begin();

   Serial.println("i2s set rate");
 //  i2s_set_rate(22050);
  i2s_set_rate(8000);

   // read PCM samples from array or spiffs ...

   Serial.println("i2s write sample");
   for ( int i=0; i<65536; i++) {
      i2s_write_lr(i, i);   // this gives a steady buzzing
//      int sx = sampToI2sPwm(i); // this gives clicks and high pitch tones
//      i2s_write_lr(sx, sx);   
      if ((i % 1000) == 0) yield(); // without this get WDT resets
   }

   Serial.println("i2s end");
   i2s_end();
}

// These from the i2s demo look useful  https://github.com/espressif/ESP8266_MP3_DECODER

//Array with 32-bit values which have one bit more set to '1' in every consecutive array index value
const unsigned int ICACHE_RODATA_ATTR fakePwm[]={ 0x00000010, 0x00000410, 0x00400410, 0x00400C10, 0x00500C10, 0x00D00C10, 0x20D00C10, 0x21D00C10, 0x21D80C10, 
  0xA1D80C10, 0xA1D80D10, 0xA1D80D30, 0xA1DC0D30, 0xA1DC8D30, 0xB1DC8D30, 0xB9DC8D30, 0xB9FC8D30, 0xBDFC8D30, 0xBDFE8D30, 
  0xBDFE8D32, 0xBDFE8D33, 0xBDFECD33, 0xFDFECD33, 0xFDFECD73, 0xFDFEDD73, 0xFFFEDD73, 0xFFFEDD7B, 0xFFFEFD7B, 0xFFFFFD7B, 
  0xFFFFFDFB, 0xFFFFFFFB, 0xFFFFFFFF};

int sampToI2sPwm(short s) {
  //Okay, when this is enabled it means a speaker is connected *directly* to the data output. Instead of
  //having a nice PCM signal, we fake a PWM signal here.
  static int err=0;
  int samp=s;
  samp=(samp+32768);  //to unsigned
  samp-=err;      //Add the error we made when rounding the previous sample (error diffusion)
  //clip value
  if (samp>65535) samp=65535;
  if (samp<0) samp=0;
  //send pwm value for sample value
  samp=fakePwm[samp>>11];
  err=(samp&0x7ff); //Save rounding error.
  return samp;
}

//Reformat the 16-bit mono sample to a format we can send to I2S.
static int sampToI2s(char s) {
  //We can send a 32-bit sample to the I2S subsystem and the DAC will neatly split it up in 2
  //16-bit analog values, one for left and one for right.

  //Duplicate 16-bit sample to both the L and R channel
  int samp=s;
  samp=(samp)&0xffff;
  samp=(samp<<16)|samp;
  return samp;
} 

[bbx10]

http://www.esp8266.com/viewtopic.php?f=11&t=11790

Here is an example for playing WAV files via I2S interface.

[devyte]

Arduino reference for the class is here.

[Protonerd]

Is there an easy way to convert mono wav files to I2S format in run time? The referenced Arduino I2S lib can only play stereo files but most of the files I want to play are mono coded.
Or does I2S have a mono operating mode?

[tedhsieh1966]

Is there any way to play 20, 24, 32 bits audio?

[teaalltr]

Any news on i2s audio input?

[tedhsieh1966]

I tried but it did not work. 從 Windows 10 的郵件傳送 寄件者: Piruzzolo 傳送時間: 2019年9月9日 下午 08:06 收件者: esp8266/Arduino 副本: tedhsieh1966; Comment 主旨: Re: [esp8266/Arduino] I2S Support (#427) Any news on i2s audio input? — You are receiving this because you commented. Reply to this email directly, view it on GitHub, or mute the thread.

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