ESP32 Forum

Good afternoon,

I have tried to implement a pipe in order to decode a MP3 file on a SDCard and to sent it to an audio amplifier using I2S.

The program compiles normally, using an oscilloscope, I can see datas on the I2S_Out, so I think that the MP3 file is decoded and sent.
However, the LR_CLK and the BIT_CLK are not OK.

I would like to have a LR_CLK = 16KHz (Equal to the sample rate) but I have a LR_CLK = 1,3KHz.
The BIT_CLK is 96Khz.
So I do not ear anything on my amplifier.

Here is my config :
i2s_stream_cfg_t i2s_cfg;
i2s_cfg.type = AUDIO_STREAM_WRITER;
i2s_cfg.i2s_config.mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_TX);
i2s_cfg.i2s_config.sample_rate = 16000;
i2s_cfg.i2s_config.bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT;
i2s_cfg.i2s_config.channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT;
i2s_cfg.i2s_config.communication_format = I2S_COMM_FORMAT_STAND_I2S;
i2s_cfg.i2s_config.intr_alloc_flags = ESP_INTR_FLAG_LEVEL2 | ESP_INTR_FLAG_IRAM;
i2s_cfg.i2s_config.dma_buf_count = 3;
i2s_cfg.i2s_config.dma_buf_len = 300;
i2s_cfg.i2s_config.use_apll = false;
i2s_cfg.i2s_config.tx_desc_auto_clear = true;
i2s_cfg.i2s_config.fixed_mclk = 0;
i2s_cfg.i2s_config.mclk_multiple = I2S_MCLK_MULTIPLE_384;
i2s_cfg.i2s_port = I2S_NUM_0;
i2s_cfg.use_alc = false;
i2s_cfg.volume = 0;
i2s_cfg.out_rb_size = I2S_STREAM_RINGBUFFER_SIZE;
i2s_cfg .task_stack = I2S_STREAM_TASK_STACK;
i2s_cfg.task_core = I2S_STREAM_TASK_CORE;
i2s_cfg.task_prio = I2S_STREAM_TASK_PRIO;
i2s_cfg.stack_in_ext = false;
i2s_cfg.multi_out_num = 0;
i2s_cfg.uninstall_drv = true;
i2s_cfg.need_expand = false;
i2s_cfg.expand_src_bits = I2S_BITS_PER_SAMPLE_16BIT;
i2s_stream_writer = i2s_stream_init(&i2s_cfg);

Could you please help me on the subject ?

Best regards,

Thomas TRUILHE.

Hello ThomasESP32

at first it is recommended to initialise your config with and then override the default config values

If you have no i2s to DAC chip you have to use the internal one

for this you have to define
SOC_I2S_SUPPORTS_ADC_DAC

you also can use
i2s_stream_set_clk(audio_element_handle_ti2s_stream, int rate, int bits, int ch)

to set the clock and bit rate

Best regards

Hello Thomas

at first it is recomended to initialise your struct like this: and then override the default values

like in the samples

if you do not have an i2s to dac then you need to define you can also try this function to set the clock there are also a lot of examples in esp-adf
https://github.com/espressif/esp-adf/tr ... p3_control

best regards