ESP32 Forum

Posted: **Sat Aug 10, 2019 12:33 pm**

I'm trying to use I2S and internal DAC to play WAV files from SPIFF on a Heltec WiFi LoRa 32 V2, using the Arduino IDE.

I have an audio amp and an oscilloscope hooked up to DAC2 (pin 25) of the board and I'm not getting any signal. I've simplified the problem by generating a sine wave (as in the ESP-IDF examples). Here's the code:

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#include <Streaming.h>
#include <driver/i2s.h>
#include "freertos/queue.h"
 
#define SAMPLE_RATE     (22050)
#define SAMPLE_SIZE     4000
#define PI              (3.14159265)
#define I2S_BCK_IO      (GPIO_NUM_26)
#define I2S_WS_IO       (GPIO_NUM_25)
#define I2S_DO_IO       (GPIO_NUM_22)
#define I2S_DI_IO       (-1)
 
 
size_t i2s_bytes_write = 0;
static const int i2s_num = 0;
 
int sample_data[SAMPLE_SIZE];
 
i2s_config_t i2s_config = {
    .mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_TX | I2S_MODE_DAC_BUILT_IN),                                  // Only TX
    .sample_rate = SAMPLE_RATE,
    .bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT,
    .channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,                           //2-channels
    .communication_format = (i2s_comm_format_t)I2S_COMM_FORMAT_I2S,
    .intr_alloc_flags = 0,//ESP_INTR_FLAG_LEVEL1   
    .dma_buf_count = 8,
    .dma_buf_len = 64,
    .use_apll = false                           //Interrupt level 1
};
 
i2s_pin_config_t pin_config = {
    .bck_io_num = I2S_BCK_IO,
    .ws_io_num = I2S_WS_IO,
    .data_out_num = I2S_DO_IO,
    .data_in_num = I2S_DI_IO                                               //Not used
};
 
static void setup_sine_wave()
{
    unsigned int i;
    int sample_val;
    double sin_float;
    size_t i2s_bytes_write = 0;
 
    for (i = 0; i < SAMPLE_SIZE; i++)
    {
        sin_float = sin(i * PI / 180.0);
        sin_float *= 127;
        sample_val = (uint8_t)sin_float;
        sample_data[i] = sample_val;
        Serial << sample_data[i] << ",";
        delay(1);
    }
    Serial << endl << "Sine wave generation complete" << endl;
}
 
void setup() {
    pinMode(26, OUTPUT);
    Serial.begin(115200);
    i2s_driver_install(I2S_NUM_0, &i2s_config, 0, NULL);
    //i2s_set_pin(I2S_NUM_0, NULL);
    i2s_set_pin(I2S_NUM_0, &pin_config);
    i2s_set_dac_mode(I2S_DAC_CHANNEL_RIGHT_EN);
    i2s_set_sample_rates(I2S_NUM_0, 22050); //set sample rates
    setup_sine_wave();
    i2s_set_clk(I2S_NUM_0, SAMPLE_RATE, I2S_BITS_PER_SAMPLE_16BIT, I2S_CHANNEL_MONO);
    i2s_write(I2S_NUM_0, &sample_data, SAMPLE_SIZE, &i2s_bytes_write, 500);
    i2s_driver_uninstall(I2S_NUM_0); //stop & destroy i2s driver
}
 
void loop() 
{
    i2s_driver_install(I2S_NUM_0, &i2s_config, 0, NULL);
    i2s_write(I2S_NUM_0, &sample_data, SAMPLE_SIZE, &i2s_bytes_write, 500);
    delay(100);
    i2s_driver_uninstall(I2S_NUM_0);
    delay(10);
}

The code uploads and runs OK but I still get no signal on pin 25. I also looked on pin 26 (DAC1) but that seems to be used by LoRa_IRQ. Can anyone help me out?

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Trouble playing WAV on ESP32 using I2S with internal DAC

Trouble playing WAV on ESP32 using I2S with internal DAC