bt_conn_disconnect() - ASSERTION FAILED [err == 0] k_sem_take return err -11

RE: bt_conn_disconnect() - ASSERTION FAILED [err == 0] k_sem_take return err -11

Victor Groux — Mon, 29 Jul 2024 07:17:39 GMT

Hi,

I'm quite surprised but this '\0' was indeed missing. Thank you very much.

Concerning bt_conn_foreach, I think it did not work because it was executed in an interrupt. Using first the flag logic suggested by Hieu solved this problem. After using a flag, I changed the logic to use the workqueue and now it works fine.

Again, thanks

Victor

RE: bt_conn_disconnect() - ASSERTION FAILED [err == 0] k_sem_take return err -11

Susheel Nuguru — Sat, 27 Jul 2024 17:48:30 GMT

Victor, I think the reason you have the garbage after the device name is because log_strdup does not make use of the struct bt_data->datalen.

Easiest would be to append a '\0' to data->data[bt_data->data_len] and then log_strdup might handle this better.

I am also unsure why bt_conn_foreach does not work for disconnecting for each connection. If you are pretty sure that you have more than one device connected at this point, then bt_conn_foreach should have looped through them. I did a quick test at my end and it seems that it disconnects both devices that I was connected to.

RE: bt_conn_disconnect() - ASSERTION FAILED [err == 0] k_sem_take return err -11

Victor Groux — Tue, 23 Jul 2024 08:51:50 GMT

Hi Simon,

If you mean to directly use the data->data to print with the print format %s, I've already tried but it didn't solve the output, even using printk() instead of the logging API alone or with the config CONFIG_LOG_PRINTK=y didn't change anything at all.

Kind regards,
Victor

RE: bt_conn_disconnect() - ASSERTION FAILED [err == 0] k_sem_take return err -11

Simonr — Tue, 23 Jul 2024 07:28:12 GMT

Hieu is out of office so I have taken over this case in his place

Okay, it seems like the Device name fills the remaining possible bytes with gibberish for some reason here, but I'm not able to see why exactly. I'm not familiar with the log_strdup wrapper, but could you maybe use just a string instead of the wrapper, as I'm suspecting the wrapper to be the reason for this.

Best regards,

Simon

RE: bt_conn_disconnect() - ASSERTION FAILED [err == 0] k_sem_take return err -11

Victor Groux — Wed, 17 Jul 2024 07:16:37 GMT

Update:

I just remove the while loop in my main function and use the system workqueue to call my disconnect function. It works exactly as I want and I don't have pending print anymore.

[quote userid="134549" url="~/f/nordic-q-a/112882/bt_conn_disconnect---assertion-failed-err-0-k_sem_take-return-err--11/494113"][00:00:00.462,860] <inf> main: Device name: Zenfone 9Ϋ��(�<�
...
[00:00:02.539,001] <inf> main: Device name: Zenfone 9��89��[/quote]

However, I still have this artifacts. The only peripheral's device name that is print normally is a Sony WH-1000XM4. Around me, there are some Jabra headsets, a nRF52805, a WH-1000XM3 and some connected watches too that don't print well either.

RE: bt_conn_disconnect() - ASSERTION FAILED [err == 0] k_sem_take return err -11

Victor Groux — Tue, 16 Jul 2024 11:30:49 GMT

Hi Hieu,

Thanks for the answer, I couldn't respond earlier due to vacation.

As you advised, I replace every printk() call by the logging API (LOG_INF(), sometimes LOG_WRN(), etc...).

In the button's callback function, I replace the ble_disconnect_all() call to set a flag as true and at the end of my main() function, I put a infinite loop that check the value of that flag and if it's true, it will call ble_disconnect_all() and then set the flag to false.

It works great but now, the logging API's calls doesn't print anything. It seems that the while(1) block the logging API but I don't really understand why.
When I put a break in my if statement inside the loop, every LOG_XXX() print is suddenly flush to the serial terminal only when the break triggered. Using the blocking printk() instead of the Logging API doesn't made this problem appears.

int main(void)
{
  LOG_INIT();

  // Init Bluetooth subsystem
  int err = bt_enable(NULL);
  if (err)
  {
    LOG_ERR("Bluetooth init failed (err %d)", err);
    return  1;
  }
  LOG_INF("Bluetooth initialized");
  flag_ble_disconnect = false;

  // Init Button
  err = button_init();
  if (err)
  {
    LOG_ERR("Button init failed (err %d)", err);
    return err;
  }
  
  start_scan();

  while (1)
  {
    if (flag_ble_disconnect)
    {
      ble_disconnect_all();
      flag_ble_disconnect = false;
      
      // Without this break, every LOG_XXX() seems to be ignored.
      // With this break, the LOG_XXX() prints ONLY after the break's trigger...
      break;
      // It is a problem because if this break is here, the disconnect function can't be called multiple time.
    }
  }
  return 0;
}

Can the workqueue resolve this problem ? If yes, why ?

Isn't this flag logic come with some concurrence problems like data races ?

And I have one more question. In the bt_parse_data callback, I check if the data type is BT_DATA_NAME_COMPLETE and if it's the case, I'm logging it. However the name that is printed contains some artifacts that aren't the same every time it is printed. Why is it printed like that and how can I resolve this print ?

static bool parse_data_cb(struct bt_data *data, void *user_data)
{
  bt_addr_le_t *addr = user_data;

  switch (data->type)
  {
    case BT_DATA_NAME_SHORTENED:
    case BT_DATA_NAME_COMPLETE:
      LOG_INF("Device name: %s", log_strdup(data->data));
      
      // Connecting to my phone. This condition will change in the future
      if (strncmp(data->data, "Zenfone 9", data->data_len) == 0)
      {
        int err = bt_le_scan_stop();
        if (err)
        {
          LOG_ERR("Stop LE scan failed (err %d)", err);
          return false;
        }

        struct bt_conn_le_create_param *create_param = BT_CONN_LE_CREATE_CONN;
        struct bt_le_conn_param *param = BT_LE_CONN_PARAM_DEFAULT;
        
        err = bt_conn_le_create(addr, create_param, param, &default_conn);
        if (err)
        {
          LOG_WRN("Connection failed (err %d)", err);
          start_scan();
        }
      }
      break;
    default:
      break;
  }

  return true;
}

The print:

[00:00:00.462,860] <inf> main: Device name: Zenfone 9Ϋ��(�<�
...
[00:00:02.539,001] <inf> main: Device name: Zenfone 9��89����

Anyway, it's just a visual problem in the terminal, the connection works perfectly. This issue appears with all devices that are advertising their name (there are about 10 different peripherals around me that are advertising their name).

It is my first embedded application so I don't really have a good understanding of what is going under the hood and how it's working.

Kind regards,
Victor

RE: bt_conn_disconnect() - ASSERTION FAILED [err == 0] k_sem_take return err -11

Hieu — Wed, 10 Jul 2024 23:14:23 GMT

Hi Victor,

In your code, last_press_time could be volatile, which helps ensuring that the value is up to date. It could also be local to the callback, but that should not affect performance/behavior.

printk() by default is in-place and blocking, so the printk() calls will prolong the execution of the callback. It might be a good idea to replace them with Logging APIs or CONFIG_LOG_PRINTK, both together with CONFIG_LOG_MODE_DEFERRED, to make printk() non-blocking.

Otherwise, I think the logic is reasonable. I also discuss a bit further on debouncing here: Zephyr debounce support

Please let me know if the flag handling improves the situation. If that works, you might also want to consider upgrading it to using workqueue or other Zephyr kernel services.

Regards,

Hieu

RE: bt_conn_disconnect() - ASSERTION FAILED [err == 0] k_sem_take return err -11

Victor Groux — Wed, 10 Jul 2024 09:49:09 GMT

Hi Hieu,

I thought about this problem when I wrote the code. I made a protection with a timer to be sure that the handler isn't called multiple times. This is my callback and init functions concerning that button:

#define BUTTON_TIMEOUT_MS 250

static uint64_t last_press_time = 0;

static const struct gpio_dt_spec button = GPIO_DT_SPEC_GET(DT_NODELABEL(button0), gpios);
static struct gpio_callback button_cb_data;

static void button_disconnect_cb(const struct device *dev, struct gpio_callback *cb, uint32_t pins)
{
  uint64_t now = k_uptime_get();
  if ((now - last_press_time) > BUTTON_TIMEOUT_MS)
  {
    printk("Disconnect every devices...\n");
    ble_disconnect_all();
    last_press_time = now;
  }
  else
  {
    printk("Pls wait a bit\n");
  }
}

int button_init(void)
{
  if (!device_is_ready(button.port))
  {
    printk("Error: button device %s not ready\n", button.port->name);
    return 1;
  }
  int ret = gpio_pin_configure_dt(&button, GPIO_INPUT);
  if (ret)
  {
    printk("Error: %d: failed to configure %s pin %d\n", ret, button.port->name, button.pin);
    return 1;
  }
  ret = gpio_pin_interrupt_configure_dt(&button, GPIO_INT_EDGE_TO_ACTIVE);
  if (ret)
  {
    printk("Error: %d: failed to configure interrupt on %s pin %d\n", ret, button.port->name, button.pin);
    return 1;
  }

  // Setup button callback
  gpio_init_callback(&button_cb_data, button_disconnect_cb, BIT(button.pin));
  gpio_add_callback(button.port, &button_cb_data);
  return 0;
}

Do you think that's a good way to resolve button bounce ? Is it enough ?

I'm going to try with the flag logic.

Thanks,
Victor

RE: bt_conn_disconnect() - ASSERTION FAILED [err == 0] k_sem_take return err -11

Hieu — Wed, 10 Jul 2024 09:22:50 GMT

Hi Victor,

I suspect that the button was bouncing, causing the handler to be called multiple times.

Could you please update the logic so that the button handler simply raises a flag, and the disconnection code happens elsewhere when that flag is raised?

Hieu