Managed to get audio/sound working on SC01-Plus via I2S

[hb020]

Here is what is needed to get I2S audio out working on a SC01-Plus that uses a NS4168 I2S speaker driver.

2 examples: file playing from LittleFS, or beeps. Used for an alarm clock, so sound just repeats.

You must use a rather low sample rate, as otherwise you'll get a lot of audible glitches. I used 11025. So don't count on hifi.

I also used the WAV format, as it is low on CPU load. MP3 will require another decoder (just swap it out, see WAVDecoder()) and will load the CPU more.

It has external volume control, that you can drive directly from the UI via hasp_find_obj_from_page_id().

in platformio_override.ini:

lib_deps =
    ; add the stuff that is in upstream in your device, the following is an example for [env:wt32-sc01-plus_16MB]
    ${arduino_esp32s3_v2.lib_deps}
    ${lovyangfx.lib_deps}
    ; my extra stuff
    https://github.com/pschatzmann/arduino-audio-tools.git

in my_custom.cpp (you must of course activate custom code):

somewhere at the top:

#define SOUND_FROM_FILE
// The sound file MUST be PCM 11025Hz, 16bit, mono
#define SOUND_FILE "/alarm.wav"

#include "AudioTools.h"

#define I2S_LRCK 35
#define I2S_BCLK 36
#define I2S_DOUT 37

// Don't use speakers of less than 8 Ohm, or you will damage the amplifier
// Don't use speakers of less than 1W (ideally: 3W or more), or you will easily damage the speaker. 

// sample rate: 44100 makes for a LOT of glitches, 11025 is mostly OK for below 5kHz sound
// bit rate: MUST be 16 or 24, otherwise crashes and/or speaker damage
AudioInfo sound_info(11025, 1, 16); // 11kHz, mono, 16 bit
// Output in the sound chain:
I2SStream sound_out;  // Output to I2S, speaker driver
VolumeStream volume(sound_out); // volume controller

#ifdef SOUND_FROM_FILE
// sound chain input: File
#include "AudioTools/AudioCodecs/CodecWAV.h"
#include "LittleFS.h"
File audioFile;
EncodedAudioStream sound_dec(&volume, new WAVDecoder());
StreamCopy sound_copier; // copies sound into decoder
#else
// sound chain input: generator (sine wave, in beep mode: 1hz, 0.5s)
FastSineGenerator<int16_t> sound_gen(32768, 0);  // fast wave generator, full volume
GeneratedSoundStream<int16_t> sound_in(sound_gen); 
TimedStream timed_sound_in(sound_in, 0, 1); // plays sound for a certain time
StreamCopy sound_copier(volume, timed_sound_in); // copies sound into sound_out
#endif

somewhere lower:

void custom_setup()
{
    ........

    // initialise sound
    // Logging enabled only during setup, too noisy afterwards
    AudioLogger::instance().begin(Serial, AudioLogger::Info);

    auto config = sound_out.defaultConfig(TX_MODE);
    config.copyFrom(sound_info); 
    // NS4168 pins on ESP32 SC01 Plus: LRCK=35, BCLK=36, DOUT=37
    config.pin_ws = I2S_LRCK;
    config.pin_bck = I2S_BCLK;
    config.pin_data = I2S_DOUT;
    config.i2s_format = I2S_PHILIPS_FORMAT; 
    config.channel_format = I2S_CHANNEL_FMT_ONLY_RIGHT; // mono out anyway
    // Not sure if the following helps. It will not help with the newer SDK
    // config.buffer_count = 6; // default value
    // config.buffer_size = 1024; // 2 * default value

    // start speaker driver with config
    bool sound_sink_on = sound_out.begin(config);
#ifdef SOUND_FROM_FILE
    // start sound decoder with file
    audioFile = LittleFS.open(SOUND_FILE, "r");
    sound_dec.begin();
    sound_copier.begin(sound_dec, audioFile);
    LOG_INFO(TAG_CUSTOM, "Sound started: sink: begin=%d, active=%d.", sound_sink_on, sound_out.isActive());
#else
    // start sound generator with config and a C5 tone (about 523hz)
    sound_gen.begin(sound_info, N_C5);

    // Set the timer for the sound, 500msec bursts
    timed_sound_in.setEndMs(500); // 500ms
    timed_sound_in.begin(sound_info);

    bool sound_source_on = sound_in.begin();
    LOG_INFO(TAG_CUSTOM, "Sound started: source: begin=%d, active=%d, sink: begin=%d, active=%d.", sound_source_on, sound_in.isActive(), sound_sink_on, sound_out.isActive());
#endif

    // set initial volume
    volume.begin(config); // we need to provide the bits_per_sample and channels
    volume.setVolume(0.1);

    // and the loop must contain the copy operation:
    // sound_copier.copy();

    // Sound is set up. Now we can disable "verbose" logging.
    AudioLogger::instance().setLogLevel(AudioLogger::Error);

#endif
}

void custom_loop()
{
    // Non-blocking code here, this should execute very fast! 

    ........

    // maintain sound stream from generator to output
    sound_copier.copy();
}

void custom_every_second()   // or in whatever other place....
{
    // This is called every second

    ........

    if (alarm_should_be_sounding()) {
        // activate sound and set volume
        volume.setVolume(get_alarm_volume());

#ifdef SOUND_FROM_FILE
        // if file is not or no longer playing, repeat it.
        if (!sound_copier.available() || !sound_copier.isActive()) {
            // play sound from file
            LOG_INFO(TAG_CUSTOM, "Restarting sound playing from file.");
            // go to begin of file
            audioFile.seek(0);
            sound_copier.setActive(true); // and activate the copier
        }
#else
        // if beep is not or no longer playing, repeat it.
        // If the duration is more than 1 sec, move to another place of course, like custom_every_5seconds()
        if (!sound_in.isActive()) {
            sound_in.begin();
        }
        // define and start burst
        // not really needed, as it was set before, but anyway...
        timed_sound_in.setStartMs(0);
        timed_sound_in.setEndMs(500); // 500ms 
        // start the sound burst
        timed_sound_in.begin();
#endif        
    } else {
        // sound should be off
#ifdef SOUND_FROM_FILE
        if (sound_copier.isActive()) {
            sound_copier.setActive(false); // and deactivate the copier 
        }
#else               
        if (sound_in.isActive()) {
            sound_in.end(); // This just kills the sound source
        }
#endif
    }
#endif

    ........

}


bool custom_pin_in_use(uint8_t pin)
{
    switch(pin) {
        ........
        case I2S_LRCK:
        case I2S_BCLK:
        case I2S_DOUT:
            return true;
        default:
            return false;
    }
}