CDC ACM does not work after restart

RE: CDC ACM does not work after restart

Simonr — Fri, 09 Jun 2023 07:31:20 GMT

Hi Andreas

I asked one of my colleagues that has more experience with the Dongle than me as well, but we can't see why this would occur I'm afraid. You could maybe try to add a watchdog or some timeout so that the service (or Dongle) restarts itself if is pending for X amount of time.

I'm sorry that we don't have a more concise fix for you...

Best regards,

Simon

RE: CDC ACM does not work after restart

Andreas48752 — Wed, 07 Jun 2023 10:14:51 GMT

Hi Simon,

thanks for your answer.

We did some more testing and it looks like this:

After I start the PC with connected nrf dongle it is not possible for the service to send data to the dongle. I startet an serial port monitor and I can see that the service tries to send data but it is in pending state forever.

When I restart the service or unplug the dongle and plug it in again it works fine and the service can send data.

I think it is something that the nrf firmware does not open the port correctly on the dongle side (or maybe some events are not triggered, I don't know).

As a workaround the customer restarts the service if it can't send data. This works but it would be nice if it should not be necessary at every start...

Can you image a scenario where the sdk does not initialize correctly right after the pc is started? If I connect the debugger and unplug and plug in again (so the dongle does not loose power supply) it works fine.

Thanks,

Andreas

RE: CDC ACM does not work after restart

Simonr — Thu, 01 Jun 2023 08:12:25 GMT

I just assumed it was a continuation to some other case since you started with "I did some more testing".

From your description this seems like this is an issue with the service on the PC side, which we're not experts at, as we focus on the nRF SoCs and products. I did a quick search internally looking for cases in the past with a similar issue, but didn't find anything that seemed to cover what you're seeing unfortunately. Would it be an idea to restart the service on the PC side during boot-up for example, is that an option?

Best regards,

Simon

RE: CDC ACM does not work after restart

Andreas48752 — Tue, 30 May 2023 10:22:48 GMT

Hi Simon.
no Problem at all. We also had a public holiday yesterday.

It is something completely different than the other thread. No ANT+ is needed here. Also S140 is used.

The problem ist that the PC software is not using DTR, so I tried to change some parts of app_usbd_cdc_acm.c.

This is what I changed. It works sofar, but sometimes after starting the pc the dongle does not receive any data. If I restart the service on PC side (which closes and opens the port) it works again.

ret_code_t app_usbd_cdc_acm_read(app_usbd_cdc_acm_t const * p_cdc_acm,
                                 void *                     p_buf,
                                 size_t                     length)
{
    ASSERT(p_buf != NULL);
    ret_code_t ret;
    app_usbd_cdc_acm_ctx_t * p_cdc_acm_ctx = cdc_acm_ctx_get(p_cdc_acm);

    if (0U == (p_cdc_acm_ctx->line_state & APP_USBD_CDC_ACM_LINE_STATE_DTR))
    {
        /*Port is not opened*/
       //return NRF_ERROR_INVALID_STATE; //we are talking to a pc. this is not needed




    }

static ret_code_t setup_req_class_out(app_usbd_class_inst_t const * p_inst,
                                      app_usbd_setup_evt_t const *  p_setup_ev)
{
    app_usbd_cdc_acm_t const * p_cdc_acm = cdc_acm_get(p_inst);
    app_usbd_cdc_acm_ctx_t *   p_cdc_acm_ctx = cdc_acm_ctx_get(p_cdc_acm);

    switch (p_setup_ev->setup.bRequest)
    {
       ...
        case APP_USBD_CDC_REQ_SET_CONTROL_LINE_STATE:
        {
            if (p_setup_ev->setup.wLength.w != 0)
            {
                return NRF_ERROR_NOT_SUPPORTED;
            }

            NRF_LOG_INFO("REQ_SET_CONTROL_LINE_STATE: 0x%x", p_setup_ev->setup.wValue.w);

            bool old_dtr = (p_cdc_acm_ctx->line_state & APP_USBD_CDC_ACM_LINE_STATE_DTR) ?
                            true : false;            
            p_cdc_acm_ctx->line_state = 1;// todo changed so it will work if no DTR is set from PC;// p_setup_ev->setup.wValue.w;            
            bool new_dtr = (p_cdc_acm_ctx->line_state & APP_USBD_CDC_ACM_LINE_STATE_DTR) ?
                            true : false;

            if (old_dtr == new_dtr)
            {
                return NRF_SUCCESS;
            }

            const app_usbd_cdc_acm_user_event_t ev = new_dtr ?
                  APP_USBD_CDC_ACM_USER_EVT_PORT_OPEN : APP_USBD_CDC_ACM_USER_EVT_PORT_CLOSE;

            user_event_handler(p_inst, ev);

ret_code_t app_usbd_cdc_acm_read_any(app_usbd_cdc_acm_t const * p_cdc_acm,
                                     void *                     p_buf,
                                     size_t                     length)
{
    ASSERT(p_buf != NULL);
    ret_code_t ret;
    app_usbd_cdc_acm_ctx_t * p_cdc_acm_ctx = cdc_acm_ctx_get(p_cdc_acm);

    if (0U == (p_cdc_acm_ctx->line_state & APP_USBD_CDC_ACM_LINE_STATE_DTR))
    {
        /*Port is not opened*/
        //return NRF_ERROR_INVALID_STATE; // we are talking to a pc. this is not needed
       
    }

RE: CDC ACM does not work after restart

Simonr — Tue, 30 May 2023 09:30:44 GMT

Hi Andreas

First off, sorry about the late reply, but yesterday (Monday May 29th) was a public holiday here in Norway. I just wanted to check if this is a continuation of this thread you have with my colleague Jonathan, or if it's something completely different?

Best regards,

Simon