Using bt_le_adv_update_data()

[CktDesigner]

This is a continuation of Case ID: 272157

That case resolved issues I had dynamically changing the device name (and having that new name show up in advertising).

It seemed to work OK when developing the code using the nRF52840-DK board.

i'm now using that code with nRF Connect SDK 2.0.0 and Visual Studio code (and Zephyr) on a custom board.   The target device is nrf52840 in a BL654PA module.

The code to "rename" the device is:

int newBleAdvName(char *newName) {
  int err;

  // Update the device name
  printk("Set new name: %s\n",newName);
  err = bt_set_name(newName);
  if(err) {
    printk("Error setting device name: %d\n", err);
  } else {
printk("Changed device name to: %s\n", newName);
    // Update the advertising and scan response data needed to update the advertised device name
    // Only need to modify the scan response data in this example as name is in scan response here.
    sd->data = newName;
    sd->data_len = strlen(newName);
    err = bt_le_adv_update_data(ad, ARRAY_SIZE(ad), sd, ARRAY_SIZE(sd));
    if(err) {
      printk("Error setting advertised name: %d\n", err);
    } else {
printk("Changed advertised name to: %s\n", newName);
    }
  }
  return err;
}

When invoked, function fails, returning error code -11    From errno.h        #define EAGAIN 11       /**< No more contexts */  

Here is a screen capture of the RTT console output during that time:

If I set a breakpoint to try to step through, I get an exception:

I suspect this is due to some real-time interaction with the BLE stack, so I think the error code message is what I need to resolve.

It's unclear to me what "No more contexts" means or how to correct this.

Do you have any suggestions?

Thanks!

[CktDesigner]

As a test, I commented out the three lines (847-849) of adv.c, where the BT_ADV_ENABLED flag is tested.    This eliminates the test that causes the name-change failure.    

This results in the name being changed as intended/expected.   

So now the question becomes, does this break anything else?    Is this a "bug" in this function?

Thanks...

[Susheel Nuguru]

I cannot see that there is anything in the specification that says that the advertiser needs to be enabled to change the data. It seems like this check might not be needed to update the advertising data offline (when advertiser is not running)

[CktDesigner]

OK, thanks...   I'll continue to "comment it out" in my code.    Can you start the process of having it removed from the official code?

Thanks!

[Susheel Nuguru]

I will start a process to review that part of code internally. Thanks for your suggestions and patience.

[Susheel Nuguru]

CktDesigner said:

Does advertising have to be active for "bt_le_adv_update_data" to execute successfully?   Is this what the "context" error refers to?

It is technically not required for the advertiser to be active (as per spec) to update the adv data while advertiser is not running. But in our solution, when you start advertiser using  bt_le_adv_start, you need to give adv data anyways to this function. So there is no point in updating the adv data when adv is not active/running. 

The if condition in question was only making sure that this logic applies that there is no point in updating adv data when adv is not running since you need to update it anyway when you start advertiser. But, I see absolutely no harm in commenting out this check.