PDM start fail

[Louis Wnag]

Hi, I'm using the nRF52840 SDK15.2.0
I'd like to get data from a digital microphone via a PDM interface. The teansfer data to speaker via a I2S interface.

Here is my problem:

In the ret_code_t nrf_drv_pdm_start(void)
{
...

nrf_pdm_task_trigger(NRF_PDM_TASK_START);
NRF_LOG_INFO("PDM TASKS START\r\n");
...
}

I can't see information "PDM TASKS START"

If I use
nrf_pdm_task_trigger(NRF_PDM_TASK_STOP);
NRF_LOG_INFO("PDM TASKS STOP\r\n");
I can see information "PDM TASKS STOP"

Thank you.

[Louis Wnag]

I try to port PDM part from thingy SDK to SDK_15.2 with nRF52840.
The process hangs (no further message) after nrf_pdm_task_trigger(NRF_PDM_TASK_START).

Is there any idea what's wrong in this code?

ret_code_t nrf_drv_pdm_start(void)
{
	  ASSERT(m_cb.drv_state != NRF_DRV_STATE_UNINITIALIZED);
    ret_code_t err_code;
		
	  if (m_cb.status != NRF_PDM_STATE_IDLE)
    {
        if (m_cb.status == NRF_PDM_STATE_RUNNING)
        {
            err_code = NRF_SUCCESS;
            printf("Function: %s, error code: %s.\r\n", (uint32_t)__func__, (uint32_t)NRF_LOG_ERROR_STRING_GET(err_code));
            return err_code;
        }
        err_code = NRF_ERROR_BUSY;
        printf("Function: %s, error code: %s.\r\n", (uint32_t)__func__, (uint32_t)NRF_LOG_ERROR_STRING_GET(err_code));
        return err_code;
    }
    m_cb.status = NRF_PDM_STATE_TRANSITION;
    m_cb.drv_state = NRF_DRV_STATE_POWERED_ON;
    nrf_pdm_enable();
    nrf_pdm_event_clear(NRF_PDM_EVENT_STARTED);

		nrf_pdm_task_trigger(NRF_PDM_TASK_START);
		printf("PDM-START----\r\n");	

    err_code = NRF_SUCCESS;
		printf("Function: %s, error code: %s.\r\n", (uint32_t)__func__, (uint32_t)NRF_LOG_ERROR_STRING_GET(err_code));
		return err_code;
}

ret_code_t drv_audio_enable(void)
{
	
#if CONFIG_PDM_MIC_PWR_CTRL_ENABLED
#if CONFIG_PDM_MIC_PWR_CTRL_ACT_LOW
    nrf_gpio_pin_clear(CONFIG_IO_PDM_MIC_PWR_CTRL);
#else // !CONFIG_PDM_MIC_PWR_CTRL_ACT_LOW
    nrf_gpio_pin_set(CONFIG_IO_PDM_MIC_PWR_CTRL);
#endif // CONFIG_PDM_MIC_PWR_CTRL_ACT_LOW
#endif // CONFIG_PDM_MIC_PWR_CTRL_ENABLED

    // Skip buffers with invalid data.
    m_skip_buffers = MAX(1, ROUNDED_DIV((CONFIG_PDM_TRANSIENT_STATE_LEN * SAMPLING_RATE),
                                        (1000 * CONFIG_AUDIO_FRAME_SIZE_SAMPLES)));

	  return nrf_drv_pdm_start();
}

uint32_t drv_mic_start(void)
{
    ret_code_t status;

    if(m_audio_enabled == true)
    {
        return NRF_SUCCESS;
    }
    status = drv_audio_enable();
    if (status == NRF_SUCCESS)
    {
        m_audio_enabled = true;
    }
    return status;
}

int main()
{
	drv_audio_init(m_audio_buffer_handler);
	drv_mic_start();
}

[Simon]

How do you know the program hangs at nrf_pdm_task_trigger(), and not any of the functions before? Try setting a breakpoint at nrf_pdm_task_trigger() and see if your program reaches it. Here is a guide on how to debug in SES. Usually the program stops due to asserts (like APP_ERROR_CHECK()) or hardfaults, and I guess it is one of them in your case.

Best regards,

Simon

[Louis Wnag]

Simon, Thanks your response. The program does not hang at nrf_pdm_task_trigger().

[Simon]

Ok. Just to make it clear, did you put a breakpoint on nrf_pdm_task_trigger(), and the program didn't reach the breakpoint?

If that is the case, then something before that function is causing the error. You should set a breakpoint incrementally upwards to see what line is causing the error.

Best regards,

Simon

[Louis Wnag]

I use Debug session to see what's going on.