I2S internal DAC

[Monsterhero]

Hello all,

so i'm trying to use the built-in DAC with i2s.
It's outputing audio which i'm streaming over a2dp from a android device.

My problem is, i only get a squarewave output, instead of a "analog" signal.
As a result the audio is horrible.



I tried it with the following code in my a2d data-callback:

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void a2dDataCallback(const uint8_t *buf, uint32_t len) {
	const char* data = (char*)buf;	
	i2s_write_bytes(I2S_NUM_0, data, len, portMAX_DELAY);	
}

And this is my i2s init:

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	i2s_config_t i2sconfig;
	i2sconfig.mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_TX | I2S_MODE_DAC_BUILT_IN);
	i2sconfig.bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT;
	i2sconfig.sample_rate = 44100;
	i2sconfig.channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT;
	i2sconfig.communication_format = I2S_COMM_FORMAT_I2S_MSB;
	i2sconfig.dma_buf_count = 8;
	i2sconfig.dma_buf_len = 64;
	i2sconfig.intr_alloc_flags = ESP_INTR_FLAG_LEVEL1;
	i2s_driver_install(I2S_NUM_0, &i2sconfig, 0, NULL);
	
	i2s_set_dac_mode(I2S_DAC_CHANNEL_BOTH_EN);
	i2s_set_pin(I2S_NUM_0, NULL);

Am i doing something wrong, or is it supposed to be like that?

Thanks for your help.

[ESP_Sprite]

Are you sure you aren't doing anything wrong wrt signed/unsigned and the values you input? The dac, from memory, takes the top 8 bits from the 16-bit values the I2S peripheral feeds it as unsigned bytes.

[Monsterhero]

I tried to use the original a2dp_sink example aswell, which gives me the same result.

Theres the code i tried:
https://github.com/espressif/esp-idf/tr ... /a2dp_sink

[Monsterhero]

I found the error/bug:

I used the following for I2S init:

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.mode = I2S_MODE_MASTER | I2S_MODE_TX | I2S_MODE_DAC_BUILT_IN,

I2S_MODE_DAC_BUILT_IN has a value of 32

instead of I2S_MODE_DAC_BUILT_IN i'm using I2S_MODE_PDM now, which has a value of 64

so this is the following i'm using for init now:

Code: Select all

.mode = I2S_MODE_MASTER | I2S_MODE_TX | I2S_MODE_PDM,

It looks like DAC_BUILD_IN and PDM are swaped, cause I2S_MODE_PDM outputs a 8bit dac where I2S_MODE_DAC_BUILT_IN outputs a 1bit dac.

Can someone confirm this, too?

[Monsterhero]

Correction: I2S_MODE_DAC_BUILT_IN is 16 not 32

[moefear85]

This problem still exists.

[Elijahh]

Problem still exists, even in ESP-IDF v5.0