using with PWMAudio

[shoei1944]

hi. can you tell me how to use tinyusb audio to output sound via pwmaudio? (example)
https://arduino-pico.readthedocs.io/en/latest/pwm.html

thanks!

[pschatzmann]

I have never tried but I would just write to it in the callback!
If it is locking up like I2S, then just use a queue....

[shoei1944]

ok, i made the implementation, but i have one more question: i don't have the sound level transmitted up to rp2040, what function is responsible for this? (windows)

[pschatzmann]

Don't post blocked urls!
You can access the volume with the volume(int channel) method.
To adust the volume you can just do a multiplication or use the VolumeStream of the AudioTools.
How does your solution look like: Was a direct write working ?

[shoei1944]

#include <Arduino.h>
#include <PWMAudio.h>
#include <ADCInput.h>
#include <Adafruit_TinyUSB.h>

#define SAMPLE_RATE 48000
#define BUFFER_SIZE 512 // old 32 (256)

Adafruit_USBD_Audio usb;
PWMAudio pwmAudio(PWM_PIN);  // 0 pin
PWMAudio pwmAudioR(PWM_PIN_2); // 2 pin
PWMAudio pwmAudioSub(8); // sub pins
ADCInput adc(A2, A1);

int16_t queue[QUEUE_SIZE];
volatile size_t queue_head = 0;  // Голова очереди
volatile size_t queue_tail = 0;  // Хвост очереди

size_t writeCB(const uint8_t* data, size_t len, Adafruit_USBD_Audio& ref) {
  int16_t* audio_data = (int16_t*)data;  // Приводим данные к int16_t*
  size_t samples = len / sizeof(int16_t);  // Количество семплов

  // Записываем данные в очередь
  for (size_t i = 0; i < samples; i++) {
    size_t next_tail = (queue_tail + 1) % QUEUE_SIZE;

    // Если очередь не полна, добавляем данные
    if (next_tail != queue_head) {
      queue[queue_tail] = audio_data[i];
      queue_tail = next_tail;
    } else {
      // Очередь переполнена, пропускаем данные
      break;
    }
  }

  sample_count += samples;
  return len;
}

void setup() {
  // put your setup code here, to run once:
  // adc.begin();
  // adc.setBuffers(4, BUFFER_SIZE);
  // adc.setFrequency(SAMPLE_RATE);

  pwmAudio.setBuffers(4, BUFFER_SIZE);
  pwmAudio.setFrequency(SAMPLE_RATE);
  pwmAudio.begin(); 

  pwmAudioSub.setBuffers(4, BUFFER_SIZE);
  pwmAudioSub.setFrequency(SAMPLE_RATE);
  pwmAudioSub.begin(); 

  pwmAudioR.setBuffers(4, BUFFER_SIZE);
  pwmAudioR.setFrequency(SAMPLE_RATE);
  pwmAudioR.begin(); 

  usb.setFeedbackMethod(AUDIO_FEEDBACK_METHOD_DISABLED);
  usb.setWriteCallback(writeCB);

  if (!usb.begin(SAMPLE_RATE, 2, 16)) {  // 2 канала (стерео), 16 бит
    Serial.println("USB error");
  }

  if (TinyUSBDevice.mounted()) {
    TinyUSBDevice.detach();
    delay(10);
    TinyUSBDevice.attach();
  }

}

void loop() {
  #ifdef TINYUSB_NEED_POLLING_TASK
  // Manual call tud_task since it isn't called by Core's background
  TinyUSBDevice.task();
  #endif
  while (queue_head != queue_tail) {  // Пока очередь не пуста
    int16_t left_sample = queue[queue_head];  // Читаем левый канал
    queue_head = (queue_head + 1) % QUEUE_SIZE;  // Перемещаем голову очереди

    int16_t right_sample = queue[queue_head];  // Читаем правый канал
    queue_head = (queue_head + 1) % QUEUE_SIZE;  // Перемещаем голову очереди

    // int16_t hpf_left = highPassFilter(left_sample, hpf_left, 0.0091);
    // int16_t hpf_right = highPassFilter(right_sample, hpf_right, 0.0091);
    int16_t hpf_right = 0;
    int16_t hpf_left = 0;

    int16_t boosted_left = boostHighFrequencies(left_sample * (usb.volume(1) / 100.0), hpf_left, 0.68f, 0.6);
    int16_t boosted_right = boostHighFrequencies(right_sample * (usb.volume(2) / 100.0), hpf_right, 0.68f, 0.6);

    sub_value = lowPassFilter((((left_sample * (usb.volume(1) / 100.0)) + (right_sample * (usb.volume(2) / 100.0))) / 2) * preampsub, sub_value, 0.02);

    // Передаем данные в PWM Audio
    pwmAudioR.write(boosted_right);   // Левый канал
    pwmAudio.write(boosted_left);  // Правый канал
    pwmAudioSub.write(sub_value);
  }
}

In general it works, but when there is no sound or the track is switched, clicks are heard in the audio.