Upgrading from NCSv3.0.0 to NCSv3.2.1, I2S issue

RE: Upgrading from NCSv3.0.0 to NCSv3.2.1, I2S issue

Amanda Hsieh — Mon, 26 Jan 2026 15:18:45 GMT

Hi,

The assertion happens because the driver remains in RX-only mode when start_real_data = true; is set, but then in i2s_comp_handler only TX buffer is set after if (!start_real_data) {} else {.

To change the driver operating mode (RX-only to TX-only), you must first stop the I2S using nrfx_i2s_stop, wait for NRFX_I2S_STATUS_TRANSFER_STOPPED status, and restart the I2S in TX mode.

Waiting for NRFX_I2S_STATUS_TRANSFER_STOPPED is missing in the existing code, hence a potential race condition.

Additionally, I see "dummy" RX buffer is set only once - I think it must be set continuously during the 250ms wait period in i2s_comp_handler on each NRFX_I2S_STATUS_NEXT_BUFFERS_NEEDED. I might be wrong, but I think otherwise the clock is not generated during the whole 250ms time period.

-Amanda H.

RE: Upgrading from NCSv3.0.0 to NCSv3.2.1, I2S issue

yuanFang — Mon, 26 Jan 2026 10:03:53 GMT

hi,
I tried your method, and the code is as follows:

static void i2s_comp_handler(nrfx_i2s_buffers_t const *released_bufs, uint32_t status)
{
    if (!(status & NRFX_I2S_STATUS_NEXT_BUFFERS_NEEDED)) {
        // printk("i2s No buffer stop : %d\n", status);
        return;
    }


if (!start_real_data) {
    // printk("i2s No start_real_data stop : %d\n", status);
    return;
}

    if (released_bufs->p_tx_buffer == m_buffer_tx[0]/*!(current_buf % 2)*/) {
        current_buf += 1;
        singleGetAudioDataToTxBuf(bpsk_tata, m_buffer_tx[0], m_buffer_tx[1], current_buf);
        const nrfx_i2s_buffers_t next_buffers1 = {
            .p_rx_buffer = NULL,
            .p_tx_buffer = m_buffer_tx[0],
            .buffer_size = I2S_DATA_BLOCK_WORDS};
        nrfx_i2s_next_buffers_set(&i2s_inst, &next_buffers1);
        // printk("i2s event handler 1 :%d %d %d %d\n",released_bufs->p_tx_buffer[0],m_buffer_tx[0][0], m_buffer_tx[0][1],m_buffer_tx[0][191]);
    } else if (released_bufs->p_tx_buffer == m_buffer_tx[1] /*(current_buf % 2)*/) {
        current_buf += 1;
        singleGetAudioDataToTxBuf(bpsk_tata, m_buffer_tx[0], m_buffer_tx[1], current_buf);
        const nrfx_i2s_buffers_t next_buffers2 = {
            .p_rx_buffer = NULL,
            .p_tx_buffer = m_buffer_tx[1],
            .buffer_size = I2S_DATA_BLOCK_WORDS};
        nrfx_i2s_next_buffers_set(&i2s_inst, &next_buffers2);
        // printk("i2s event handler 2 :%d %d %d %d %d %d\n",released_bufs->p_tx_buffer[0],m_buffer_tx[1][0], m_buffer_tx[1][135],m_buffer_tx[1][136],m_buffer_tx[1][190],m_buffer_tx[1][191]);
    }
    if(!released_bufs->p_tx_buffer) {
        current_buf += 1;
        singleGetAudioDataToTxBuf(bpsk_tata, m_buffer_tx[0], m_buffer_tx[1], current_buf);
        const nrfx_i2s_buffers_t next_buffers2 = {
            .p_rx_buffer = NULL,
            .p_tx_buffer = m_buffer_tx[1],
            .buffer_size = I2S_DATA_BLOCK_WORDS};
        nrfx_i2s_next_buffers_set(&i2s_inst, &next_buffers2);
        // printk("i2s event handler 0 :%d %d %d %d\n",released_bufs->p_tx_buffer[0],m_buffer_tx[1][0], m_buffer_tx[1][1],m_buffer_tx[1][191]);
    }
}
static uint32_t m_buffer_rx[2][96] = {0};

void es8311Play()
{
    current_buf = 0;
    current_index = 0;
    buf_end_flag = 0;

    start_real_data = false;

    const nrfx_i2s_buffers_t initial_buffers_test = {
        .p_rx_buffer = m_buffer_rx[0],
        .p_tx_buffer = NULL,
        .buffer_size = 1};
    int ret = nrfx_i2s_start(&i2s_inst, &initial_buffers_test, 0);
    if (ret != 0) {
        printk("Failed to start I2S111111: %d\n", ret);
    }

    pf_gpio_write(GPIO_PA_GPIO, 1);
    k_sleep(K_MSEC(250));
    start_real_data = true;
    nrfx_i2s_stop(&i2s_inst);

    es8311_i2s_start();

    do 
    {
        __WFE();
        __SEV();
        __WFE();
    } while (current_buf < BLOCKS_TO_TRANSFER);
    nrfx_i2s_stop(&i2s_inst);
}

nrfx_i2s_start()

p_tx_buffer = NULL, and a "dummy" RX buffer,size = 1

2. Turn on the PA
3. delay 250ms
4. nrfx_i2s_stop(&i2s_inst);

5. nrfx_i2s_start() ,Start sending the actual data.

After running for a period of time, a problem of system freeze was discovered.

ASSERTION FAIL [p_buffers->p_rx buffer I= ((void *)0)] @WEST_TOPDIR/modules/hal/nor di c/nr fx/drivers/sro/nr fx_i2s. c:422

Look forward to your reply!
Thanks

RE: Upgrading from NCSv3.0.0 to NCSv3.2.1, I2S issue

yuanFang — Fri, 23 Jan 2026 06:56:21 GMT

Hi，

I tried some other approaches, but the results were not as good as those of ncsv3.0.0. I wonder if any of you have better methods.

I also came up with an idea: to separate the NCSv3.0.0 I2s driver file and place it on NCSv3.2.1. During the compilation process, specify the NCSv3.0.0 I2s driver file. Will this method work?

Look forward to your reply!
Thanks

RE: Upgrading from NCSv3.0.0 to NCSv3.2.1, I2S issue

yuanFang — Fri, 23 Jan 2026 02:09:21 GMT

hi,

Thank you for your reply.

Could you please provide an example based on my description?

1. One of the devices only has the function of playing (TX) but not receiving (RX).
2. In the NCSv3.0.0 version, the actual data sent was "int16_t bpsk_tata[1521]", and the buffer_size for each I2S transmission was 192.
3. According to what you said, when TX_buffer is NULL, what should be the size of buffer_size? What should be done in the i2s_comp_handler?
4. When the delay of 250ms is over, will the actual data be directly switched in the i2s_comp_handler(), or will it be sent first by calling i2s_stop() and then I2s_start()?

The distance measurement is conducted once every 1 second. Each playback and reception must be synchronized, and the error should be within 100 microseconds. Therefore, I need to ensure that the timing when sending dummy data and then switching to real data is fixed.

Thank you very much for your kind assistance.

Look forward to your reply!
Thanks

RE: Upgrading from NCSv3.0.0 to NCSv3.2.1, I2S issue

Amanda Hsieh — Thu, 22 Jan 2026 13:41:11 GMT

[quote user="yuanFang"]I need a method that starts the I2S clock but does not send any data before calling the function nrfx_i2s_start().[/quote]

You can use nrfx_i2s_start() and provide a NULL TX buffer and a "dummy" RX buffer. This will start the actual transaction (SCK and LRCK clocks) and fill the RX buffer, but the data in the RX buffer can be ignored.

RE: Upgrading from NCSv3.0.0 to NCSv3.2.1, I2S issue

yuanFang — Thu, 22 Jan 2026 01:37:06 GMT

hi,

Thank you for your reply.

I know that I used the register and the API together.Due to the nature of the project, I had no choice but to do so, and the first version has already been verified by NCSv3.0.0.

I need a method that starts the I2S clock but does not send any data before calling the function nrfx_i2s_start().

Look forward to your reply!
Thanks

RE: Upgrading from NCSv3.0.0 to NCSv3.2.1, I2S issue

Amanda Hsieh — Wed, 21 Jan 2026 15:01:48 GMT

Hi,

From your code, it appears that you are mixing nrfx_* API calls with direct register access. This usage is not supported, and we do not test such scenarios because it is not possible to predict how users may manipulate the peripheral outside the nrfx_* API context.

The crash likely occurs because an interrupt is triggered between nrfx_i2s_init and nrfx_i2s_start. In that window, nrfx_i2s_next_buffers_set is called from the callback context. However, this function checks the driver state and expects it to be POWERED_ON, which is only set in nrfx_i2s_start.

This behavior is a direct consequence of accessing the peripheral through registers instead of exclusively using the I2S driver API.

-Amanda H.

RE: Upgrading from NCSv3.0.0 to NCSv3.2.1, I2S issue

Amanda Hsieh — Tue, 20 Jan 2026 21:03:25 GMT

Hi,

I am working on your issue and need time to get back to you.

Regards,
Amanda H.