Cannot get I2S sample working

[Elppu]

Hi!

I cannot get I2S echo sample to work on nrf54L15. Tried following overlay

&pinctrl {
	i2s20_default: i2s20_default {
		group1 {
			psels = <NRF_PSEL(I2S_SDIN, 1, 14)>,
					<NRF_PSEL(I2S_LRCK_M, 2, 7)>,
					<NRF_PSEL(I2S_SCK_M, 2, 9)>;
		};
	};
};

i2s_rxtx: &i2s20 {
	status = "okay";
	pinctrl-0 = <&i2s20_default>;
	pinctrl-names = "default";
};

build configuration  nrf54l15pdk_nrf54l15_cpuapp

I verified with oscilloscope that no clock is modulated or wordselect switched. What might be the problem?

Is the i2s driver mature on nrf54 series / something new that has to be done?

[Elppu]

I got this working using PORT_P1 and not PORT_P2  for i2s pins. Feature or bug?

[Elppu]

#include <zephyr/kernel.h>
#include <zephyr/drivers/i2s.h>
#include <zephyr/sys/printk.h>
#include <string.h>

#include <zephyr/device.h>
#include <zephyr/drivers/gpio.h>
#include <zephyr/drivers/uart.h>

#define SAMPLE_FREQUENCY    6000
#define SAMPLE_BIT_WIDTH    32
#define BYTES_PER_SAMPLE    4
#define NUMBER_OF_CHANNELS  2
#define SAMPLES_PER_BLOCK   480
#define BLOCK_SIZE          (BYTES_PER_SAMPLE * NUMBER_OF_CHANNELS * SAMPLES_PER_BLOCK)
#define TIMEOUT             1000

K_MEM_SLAB_DEFINE_STATIC(i2s_mem_slab, BLOCK_SIZE, 4, 4);

int main(void)
{
    const struct device *uart1 = DEVICE_DT_GET(DT_NODELABEL(uart21));
    if (!device_is_ready(uart1)) {
        printk("UART21 not ready!\n");
    } else {
        uart_poll_out(uart1, 'H');
        uart_poll_out(uart1, 'i');
        uart_poll_out(uart1, '\n');
    }
    printk("I2S RX example: %d Hz, %d-bit, %d channel(s), block size = %d\n",
        SAMPLE_FREQUENCY, SAMPLE_BIT_WIDTH, NUMBER_OF_CHANNELS, BLOCK_SIZE);

    const struct device *i2s_rx = DEVICE_DT_GET(DT_NODELABEL(i2s20));

    if (!device_is_ready(i2s_rx)) {
        printk("I2S RX device not ready\n");
        return 1;
    }

    struct i2s_config config = {
        .word_size = SAMPLE_BIT_WIDTH,
        .channels = NUMBER_OF_CHANNELS,
        .format = I2S_FMT_DATA_FORMAT_I2S,
        .options = I2S_OPT_FRAME_CLK_MASTER | I2S_OPT_BIT_CLK_MASTER,
        .frame_clk_freq = SAMPLE_FREQUENCY,
        .block_size = BLOCK_SIZE,
        .mem_slab = &i2s_mem_slab,
        .timeout = TIMEOUT,
    };

    int ret = i2s_configure(i2s_rx, I2S_DIR_RX, &config);
    if (ret < 0) {
        printk("I2S config failed: %d\n", ret);
        return 1;
    }

    ret = i2s_trigger(i2s_rx, I2S_DIR_RX, I2S_TRIGGER_START);
    if (ret < 0) {
        printk("I2S start failed: %d\n", ret);
        return 1;
    }

    printk("I2S RX started. Waiting for audio data...\n");

    k_sleep(K_MSEC(10));

    while (1) {
        void *mem_block;
        size_t size;

        ret = i2s_read(i2s_rx, &mem_block, &size);
        if (ret < 0) {
            printk("I2S read failed: %d\n", ret);
            // Important: Still free the mem_block if it was allocated!
            if (mem_block != NULL) {
                k_mem_slab_free(&i2s_mem_slab, &mem_block);
            }
            k_sleep(K_MSEC(10));
            continue;
        }

        printk("Read success: %d bytes\n", (int)size);

        int32_t *samples = (int32_t *)mem_block;
        int total_words = size / BYTES_PER_SAMPLE;
        int num_frames = total_words / 2;  // each stereo frame = 2 words
        
        static int frame_count = 0;

        for (int i = 0; i < num_frames; i++) {
            // Left channel is first word in each frame
            int32_t raw_left = samples[2 * i];
            int32_t left = (raw_left >> 8) & 0xFFFFFF;
            if (left & 0x800000) {
                left |= 0xFF000000;  // Sign extend
            }
        
            // Right channel is second word in each frame
            int32_t raw_right = samples[2 * i + 1];
            int32_t right = (raw_right >> 8) & 0xFFFFFF;
            if (right & 0x800000) {
                right |= 0xFF000000;  // Sign extend
            }
        
            //printk("Frame[%d]: L=%d\tR=%d\n", i, left, right);
            frame_count++;

            if (frame_count % 2 == 0) {
                //printk("Frame[%d]: L=%d\tR=%d\n", frame_count, left, right);
                printk("%d,%d\n", left, right);
                // yield to avoid flooding the log
                //k_sleep(K_MSEC(1));
                //k_yield();
            }
        }

        k_mem_slab_free(&i2s_mem_slab, &mem_block);

        k_sleep(K_MSEC(1)); // avoid log flood
    }
}

What might be the problem with this code? I get two channels printed, but it seems that it does not correctly get both channels. It seems that one mic correctly picks audio(maybe?), other channel prints some residual something that does not react as expected to external test audio.

I'm using 2  ICS-43434  on same i2s bus. Circuit and signaling works well on esp32s3 and I have confirmed that both mics work and give independent data. I have issue of replicating same feature here in nrf54l15

[Einar Thorsrud]

Hi,

Wich pins are you using now? The I2S peripheral can only be used on GPIO port P1 (see Configuration). Moreover, MCK an dSCK must be on clock pins (see Clock pins).

[Elppu]

Hi!

Thank you! Yes should read more documentation. I still have more issues.

&pinctrl {
	i2s20_default: i2s20_default {
		group1 {
			psels = <NRF_PSEL(I2S_SDIN, 1, 14)>,
					<NRF_PSEL(I2S_LRCK_M, 1, 11)>,
					<NRF_PSEL(I2S_SCK_M, 1, 12)>;
		};
	};

This is my current pins and now I get data. Next issue is that my left channel data does not seem to be correct. Right channel seem to be same as my test sound when I plot it, but left channel not. Left channel is the first word? The buffer is interleaved?

L0 R0 L1 R1 L2 R2 etc??

Clock pin seem to be now correct. How about wordselect?

Example data:

Left: 1034, Right: -1762
Left: -684, Right: -1628
Left: -680, Right: -1484
Left: 1276, Right: -1086
Left: 664, Right: -898
Left: 1120, Right: -824

Plotted from log prints:

For some reason only right channel seem to be about right maybe? Did I understand correctly how the left and right data is in the buffer? Documentation

how will this be filled with this mic? Is this correct way to get the data?

        int32_t *samples = (int32_t *)mem_block;
        int total_words = size / BYTES_PER_SAMPLE;
        int num_frames = total_words / 2;  // each stereo frame = 2 words
        
        static int frame_count = 0;

        for (int i = 0; i < num_frames; i++) {
            // Left channel is first word in each frame
            int32_t raw_left = samples[2 * i];
            int32_t left = (raw_left >> 8) & 0xFFFFFF;
            if (left & 0x800000) {
                left |= 0xFF000000;  // Sign extend
            }
        
            // Right channel is second word in each frame
            int32_t raw_right = samples[2 * i + 1];
            int32_t right = (raw_right >> 8) & 0xFFFFFF;
            if (right & 0x800000) {
                right |= 0xFF000000;  // Sign extend
            }