I2S microphone (RX)

[ppisljar]

I am trying to connect I2S mic to ESP32 with no luck. (using SPH0645LM4H-B mic)

i2s init code:
```
i2s_config_t i2s_in_config = {
mode: (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX),
sample_rate: 16000,
bits_per_sample: (i2s_bits_per_sample_t)16, // found some posts saying 32bit mode is giving extra problems ... so i am going with 16
channel_format: I2S_CHANNEL_FMT_ONLY_LEFT,
communication_format: (i2s_comm_format_t)(I2S_COMM_FORMAT_I2S | I2S_COMM_FORMAT_I2S_MSB),
intr_alloc_flags: ESP_INTR_FLAG_LEVEL1,
dma_buf_count: 8,
dma_buf_len: 64
};

// if i understand correctly i can use any IO pin
i2s_pin_config_t i2s_in_pin_config = {
bck_io_num: 16,
ws_io_num: 4,
data_out_num: -1, //Not used
data_in_num: 17
};

i2s_driver_install((i2s_port_t)0, &i2s_in_config, 0, NULL);
i2s_set_pin((i2s_port_t)0, &i2s_in_pin_config);
```

and then i loop on this
```
uint16_t sample_val;
i2s_pop_sample((i2s_port_t)0, (char *)&sample_val, portMAX_DELAY);
Serial.print(sample_val);
```

however all i am getting is 0s. I read around this forum and found some old posts mentioning that RX is not working correctly yet with I2S, however some later posts seem to suggest that some ppl were succesfull ?

i would greatly appreciate any help on this.

[derdolch]

You can read the datasheet of shp0645.
try

sample_rate: 32000 - 64000
bit_per_sample: 32
channel_format: I2S_CHANNEL_FMT_RIGHT_LEFT

In this way the BCLK will be 64th MCLK and the MIC sends Data.

I got sampled data into my esp32, but it did not work to send it to my DAC-Modul.

[BuddyCasino]

Would you mind posting your code? Because even with the latest I2S fixes in the ESP-IDF I get nothing.

Microphone I2S configuration:

Code: Select all

i2s_config_t i2s_config = {
			.mode = I2S_MODE_MASTER | I2S_MODE_RX,
			.sample_rate = 44100,
			.bits_per_sample = I2S_BITS_PER_SAMPLE_32BIT,
			.channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,
			.communication_format = I2S_COMM_FORMAT_I2S | I2S_COMM_FORMAT_I2S_MSB,
			.dma_buf_count = 14,                            // number of buffers, 128 max.
			.dma_buf_len = 32 * 2,                          // size of each buffer
			.intr_alloc_flags = ESP_INTR_FLAG_LEVEL1        // Interrupt level 1
	};

    i2s_pin_config_t pin_config = {
            .bck_io_num = GPIO_NUM_17,
            .ws_io_num = GPIO_NUM_18,
            .data_out_num = I2S_PIN_NO_CHANGE,
            .data_in_num = GPIO_NUM_5
    };

Loop:

uint64_t buffer = 0;
while(1)
{
buffer = 0;
i2s_pop_sample(I2S_NUM_1, &buffer, 10);
i2s_push_sample(I2S_NUM_0, &buffer, 10);
}

All when I look at the 'buffer' variable, all bits are set to 1.
Microphone type is SPH0645.

[BuddyCasino]

Ok, these pins work:

Code: Select all

	i2s_pin_config_t pin_config = {
			.bck_io_num = 26,
			.ws_io_num = 25,
			.data_out_num = I2S_PIN_NO_CHANGE,
			.data_in_num = 23
	};

These don't:

Code: Select all

	i2s_pin_config_t pin_config_rx = {
			.bck_io_num = 17,
			.ws_io_num = 18,
			.data_out_num = I2S_PIN_NO_CHANGE,
			.data_in_num = 5
	};

Anyone got an idea whats going on here?
Theres a pin schematic that says which pins can be used for what, but I can't make sense of it in respect to I2S: http://www.espressif.com/sites/default/ ... ist_en.pdf

[WiFive]

Maybe because the driver does not do gpio_set_direction and gpio_set_pull_mode

[ppisljar]

i tried setting pin 17 to input/input_pulldown/input_pullup ... none seem to work (with pullup i get int32 max value)

Code: Select all

void i2s_config() {
  // http://esp-idf.readthedocs.io/en/latest/api/peripherals/i2s.html
  // input
  i2s_config_t i2s_in_config = {
    mode: (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX),
    sample_rate: 64000, // tried with 44100 ... same
    bits_per_sample: (i2s_bits_per_sample_t)32,
    channel_format: I2S_CHANNEL_FMT_RIGHT_LEFT,
    communication_format: (i2s_comm_format_t)(I2S_COMM_FORMAT_I2S | I2S_COMM_FORMAT_I2S_MSB),
    intr_alloc_flags: ESP_INTR_FLAG_LEVEL1,
    dma_buf_count: 8,
    dma_buf_len: 64
  };
  i2s_pin_config_t i2s_in_pin_config = {
    bck_io_num: 16,
    ws_io_num: 4,
    data_out_num: -1, //Not used
    data_in_num: 17
  };

	pinMode(17, INPUT);
	pinMode(16, OUTPUT);
	pinMode(4, OUTPUT);


  i2s_driver_install((i2s_port_t)0, &i2s_in_config, 0, NULL);
  i2s_set_pin((i2s_port_t)0, &i2s_in_pin_config);

}


void read_i2s() {
  uint32_t sample_val = 0;
  i2s_pop_sample((i2s_port_t)0, (char *)&sample_val, portMAX_DELAY);
  Serial.print(sample_val);
}

[ppisljar]

Seems to be a buggy driver ...

on espidf 2.0 i get output from mic with the above code (however it doesnt seem to be correct output ....)
on latest version of espidf i get only 0 with the same code.

[ppisljar]

also i noticed that i need to read two 32 bit integers (stereo) ...

Code: Select all

void read_i2s() {
  uint32_t sample_val[2] = {0, 0};
  i2s_pop_sample((i2s_port_t)0, (char *)sample_val, portMAX_DELAY);
  Serial.println("==>");
  Serial.println(sample_val[0]);
  Serial.println(sample_val[1]);

}

wierd thing is that i am getting both values (and its mono microphone .... )
if i set it to mono i start getting 0 only.

the output i get is bad:

Code: Select all

4033937408
4033216512
4033413120
4032823296
4033413120
4032823296
0
0
0
0
0
0
0
0
0
.... (mix of really high values and 0 ... keeps repeating in a pattern)

[BuddyCasino]

The driver is probably not buggy, they fixed it recently. Are you using the latest ESP-IDF?

Using the SPH0645LM4H with I2S_BITS_PER_SAMPLE_32BIT, this works for me:

Code: Select all

	uint64_t buffer = 0;
	uint64_t buffer_out = 0;
	while(1)
	{
		cnt++;
		buffer = 0;
		int bytes_popped = i2s_pop_sample(I2S_NUM_0, &buffer, 10);
		buffer_out = buffer << 5;
		i2s_push_sample(I2S_NUM_0, &buffer_out, 10);
	}

Shifting by 5 was determined by try and error. The chip emits 24 bits with 18 bits of them valid followed by zeros, so this doesn't make sense to me - but it distorts with 6 (=24-18) bits.

Edit: just tested different pins, this configuration works now. The gpio_matrix_in_check() in the i2s.c driver should take care of everything:

Code: Select all

	i2s_pin_config_t pin_config_rx = {
			.bck_io_num = 17,
			.ws_io_num = 18,
			.data_out_num = I2S_PIN_NO_CHANGE,
			.data_in_num = 5
	};
	i2s_set_pin(I2S_NUM_1, &pin_config_rx);

Edit 2: I'm not sure I2S_CHANNEL_MONO actually works, I get no data.

[rudi ;-)]

The driver is probably not buggy, they fixed it recently. Are you using the latest ESP-IDF?

Using the SPH0645LM4H with I2S_BITS_PER_SAMPLE_32BIT, this works for me:

Code: Select all

	uint64_t buffer = 0;
	uint64_t buffer_out = 0;
	while(1)
	{
		cnt++;
		buffer = 0;
		int bytes_popped = i2s_pop_sample(I2S_NUM_0, &buffer, 10);
		buffer_out = buffer << 5;
		i2s_push_sample(I2S_NUM_0, &buffer_out, 10);
	}

Shifting by 5 was determined by try and error. The chip emits 24 bits with 18 bits of them valid followed by zeros, so this doesn't make sense to me - but it distorts with 6 (=24-18) bits.

Edit: just tested different pins, this configuration works now. The gpio_matrix_in_check() in the i2s.c driver should take care of everything:

Code: Select all

	i2s_pin_config_t pin_config_rx = {
			.bck_io_num = 17,
			.ws_io_num = 18,
			.data_out_num = I2S_PIN_NO_CHANGE,
			.data_in_num = 5
	};
	i2s_set_pin(I2S_NUM_1, &pin_config_rx);

@Buddy
can't test - cause have just in time no I2S HW Mic on the Hand -

in this way you did - you use successful I2S0 ( I2S_NUM_0) for output and the I2S1 ( I2S_NUM_1) for input, right?

so this config must be valid for run for the ICS.I2S as Left Channel example?
and for Left and Right ( 2 Mics ) example too?

perhabs you can look small time on this picture, please:

mic_pins_I2S.png (58.51 KiB) Viewed 39565 times

what is your saying?

best wishes
rudi