StoreProhibited Error on ESP32 when calling i2s_read function

I am trying to use a microphone sensor on my esp32 microcontroller. Currently, it is running the ESP-IDF framework. The microphone is the sph0645lm4h-b. I am using the I2S protocol to connect to the sensor.

I2S config is shown below:

    void i2s_init()
{
    i2s_config_t i2s_config = {
        .mode = I2S_MODE_MASTER | I2S_MODE_RX, // I2S_MODE_TX Only TX
        .sample_rate = 17000,
        .bits_per_sample = 32,
        // .channel_format = I2S_CHANNEL_FMT_ALL_LEFT, //2-channels
        .channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,
        .communication_format = (i2s_comm_format_t)I2S_COMM_FORMAT_I2S | I2S_COMM_FORMAT_I2S_MSB,
        .dma_buf_count = 8,
        .dma_buf_len = 64,
        .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1 //Interrupt level 1
    };
    i2s_pin_config_t pin_config = {
        .bck_io_num = 26,
        .ws_io_num = 25,
        .data_out_num = -1, //Not used
        .data_in_num = 27
        };
    i2s_driver_install(I2S_NUM, &i2s_config, 0, NULL);
    i2s_set_pin(I2S_NUM, &pin_config);
}

The code that collects data:

i2s_init(); //initializes mics 
int samples_value, samples_data;
samples_value = i2s_pop_sample(I2S_NUM, &samples_data, 2);
printf("%d,", samples_data);

When I upload the code to the microcontroller, I am getting confusing data. The outputs alternate from a really negative value and 1.

Data:

-191725568,1,-191823872,1,-191889408,1,-192020480,1,-192118784,1,-190152704,1,-190054400,1,-190021632,1

I am unsure if this is the data that I am supposed to be receiving from the microphone sensor and I read on the I2S documentation that the i2s_pop_sample is depreciated so I tried to use the i2s_read but I am getting a StoreProhibited error.

Code for i2s_read:

int *samples;
int s;
samples = &s;       //pointer initialization

i2s_read(I2S_NUM,&samples,4,4,2); 

Error:

Guru Meditation Error: Core  0 panic'ed (StoreProhibited). Exception was unhandled.
        Core 0 register dump:
    PC      : 0x400d7552  PS      : 0x00060b30  A0      : 0x800d1c9f  A1      : 0x3ffcc950
    A2      : 0x00000000  A3      : 0x3ffccaa8  A4      : 0x00000004  A5      : 0x00000004
    A6      : 0x00000002  A7      : 0x00000005  A8      : 0x800d1e72  A9      : 0x3ffcc900
    A10     : 0x3d87e746  A11     : 0x00000000  A12     : 0x00000001  A13     : 0x00000002
    A14     : 0x7f800000  A15     : 0x00000000  SAR     : 0x00000015  EXCCAUSE: 0x0000001d
    EXCVADDR: 0x00000004  LBEG    : 0x40002390  LEND    : 0x4000239f  LCOUNT  : 0x00000000

    Backtrace: 0x400d7552:0x3ffcc950 0x400d1c9c:0x3ffcc990 0x400e9994:0x3ffccae0

I'm just going to address the i2s_read() issue since i2s_pop_sample() is deprecated.

The way you're calling i2s_read(), you're using a pointer as a data buffer and passing an integer as a pointer.

Here's the prototype of i2c_read() taken from the ESP-IDF manual.

esp_err_t i2s_read(i2s_port_ti2s_num, void *dest, size_t size, size_t *bytes_read, TickType_t ticks_to_wait)

• i2s_num is the i2s port number
• dest is the address of the buffer to read the data into
• size is the size of the buffer
• bytes_read is a pointer to a size_t which will have the number of bytes read written to it
• ticks_to_wait is a timeout

There are two problems with the arguments you passed to i2s_read(). You're calling it this way:

int *samples;
int s;
samples = &s;

i2s_read(I2S_NUM,&samples,4,4,2); 

You're passing &samples as the address of the buffer. So what you're telling i2s_read() is to read 4 bytes of data and store them in samples, which doesn't make a lot of sense since it's a pointer. You should just pass &s as the buffer and skip mucking about with samples.

The second problem is you're passing 4 as the bytes_read argument. I'm actually surprised this even compiled. This makes i2s_read() attempt to store a size_t with the number of bytes read at address 4, which will certainly cause some kind of exception.

Try this:

int32_t sample;
size_t bytes_read;

i2s_read(I2S_NUM, &sample, 4, &bytes_read, 2); 

This:

1. makes no assumption about the storage size of int and guarantees a 4 byte (32 bit) integer for sample
2. correctly passes a pointer to the 4 byte integer created to hold the data read by i2s_read()
3. correctly passes a pointer to a size_t so that i2s_read() can store the number off bytes it read.

And if you want to know how many bytes were actually read, that's in bytes_read.