BLE Advertisement interval 10ms-20ms

[hari]

I am using the nRF Connect SDK broadcaster example on the nRF52840. The default advertisement interval was set to "BT_GAP_ADV_FAST_INT_MIN_2 = 0x00a0" (100ms) to "BT_GAP_ADV_FAST_INT_MAX_2 = 0x00f0" (150ms), resulting in a 100ms interval. I then changed it to 30ms-60ms using "BT_GAP_ADV_FAST_INT_MIN_1 = 0x0030" and "BT_GAP_ADV_FAST_INT_MAX_1 = 0x0060," achieving a 30ms interval.

 bt_le_adv_start(BT_LE_ADV_NCONN, ad, ARRAY_SIZE(ad),
                              NULL, 0);

Now, I want to set the advertisement interval to 10ms-20ms. I attempted to use custom definitions such as "BT_GAP_ADV_FAST_INT_MIN_1_10ms = 0x0008" and "BT_GAP_ADV_FAST_INT_MIN_1_20ms = 0x0016," but it did not work; there was no advertisement occurring.

How can I achieve the desired advertisement interval of 10ms-20ms?

Note: I have also tried adjusting the definitions, but without success. I am using the nRF Power Profiler Kit to monitor the advertisement interval.

[Karl Ylvisaker]

Hello,

Now, I want to set the advertisement interval to 10ms-20ms. I attempted to use custom definitions such as "BT_GAP_ADV_FAST_INT_MIN_1_10ms = 0x0008" and "BT_GAP_ADV_FAST_INT_MIN_1_20ms = 0x0016," but it did not work; there was no advertisement occurring.

Was this the only change you made to the project?

What was the returned error code from the bt_le_adv_start call to start advertising?

Best regards,
Karl

[hari]

CONFIG_GPIO=y
CONFIG_BT=y
CONFIG_BT_BROADCASTER=y
CONFIG_BT_HCI_VS_EXT=y
CONFIG_BT_HCI=y
CONFIG_SERIAL=y

Karl Ylvisaker said:

Was this the only change you made to the project?

Yes! this is my pro.conf

Karl Ylvisaker said:

What was the returned error code from the bt_le_adv_start call to start advertising?

Currently, no error code is being returned. Additionally, I am unable to observe any advertisement packets on the NRF52840 dongle Bluetooth sniffer.

#define BT_GAP_ADV_FAST_INT_MIN_1_10ms 0x0008
#define BT_GAP_ADV_FAST_INT_MIN_1_20ms 0x0016


#define BT_LE_ADV_NCONN_30 BT_LE_ADV_PARAM(BT_LE_ADV_OPT_USE_IDENTITY, BT_GAP_ADV_FAST_INT_MIN_1_10ms, \
                                           BT_GAP_ADV_FAST_INT_MIN_1_20ms, NULL)

void my_func(void)
{
   int err;

   err = bt_enable(NULL);

   if (err)
   {
     printk("Bluetooth init failed (err %d)\n", err);
     return;
   }
   err = bt_le_adv_start(BT_LE_ADV_NCONN_30, ad, ARRAY_SIZE(ad),
                              NULL, 0);
   if (err)
   {
     printk(" Advertisement failed (err %d)\n", err);
     return;
   }
   k_sleep(K_MSEC(100)); 

   err = bt_le_adv_stop();
   if (err)
   {
     printk("Advertising failed to stop (err %d)\n", err);
     return;
   }

   err = bt_disable();
   if (err)
   {
     printk("Bluetooth disable failed (err %d)\n", err);
     return;
   }  
}



int main(void)
{
  /*other logics*/
  while (1)
  {
    my_func();
    k_sleep(K_MSEC(2000));
  }
	return 0;
}

1.This is my observation from the power profiler, and I have attached an image from the power profiler for your reference.
which is 

hari said:

"BT_GAP_ADV_FAST_INT_MIN_1 = 0x0030" and "BT_GAP_ADV_FAST_INT_MAX_1 = 0x0060,"

2.After changing this value i get this 

hari said:

"BT_GAP_ADV_FAST_INT_MIN_1_10ms = 0x0008" and "BT_GAP_ADV_FAST_INT_MIN_1_20ms = 0x0016,"

[Karl Ylvisaker]

Hello,

Thank you for the clarifications.

Please note that the advertising interval is defined as N*0.625 ms, which in your case places the min and max at 5-10ms, which is lower than the lower boundary for advertising intervals (except for high-duty directed advertising) which is 20 ms.
There will also be added a random delay of 0-10 ms to your advertising interval, to avoid repeated collisions, which you can see in the power profiler trace.

This slipped my mind earlier, apologies for any confusion this might have caused! :) 

Still it is strange that you did not see any returned error codes, however - perhaps the logging is not set up correctly.

Best regards,
Karl