Limited Discoverable Mode VS General Discoverable Mode nRF52840 SDK16 s140

[Nikosant03]

Hi everyone,

I want to set by BLE device advertising itself for 30s and then go to sleep. To that I set the APP_ADV_DURATION = 3000. What is not clear to me is the difference between 

BLE_GAP_ADV_FLAGS_LE_ONLY_LIMITED_DISC_MODE and BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE. I've read that if you want to keep your device always advertising you have to set APP_ADV_DURATION = 0 and BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE. But what if you want to advertise for a specific time such as in my case?

I mean, whatever mode I select the result is the same (the board stop advertising after 30s). So my questions are:

1. What is the difference between BLE_GAP_ADV_FLAGS_LE_ONLY_LIMITED_DISC_MODE and BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE?

2. In my case what should I select? BLE_GAP_ADV_FLAGS_LE_ONLY_LIMITED_DISC_MODE or BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE

3. Is this somehow related to power consumption?

Thanks in advance

Nick

[Simonr]

Hi Nick

1. BLE_GAP_ADV_FLAGS_LE_ONLY_LIMITED_DISC_MODE indicates to a central that you are only available for a certain amount of time before the advertisement times out while setting BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE will enable you to set a timeout of 0 (no timeout).

If you set the advertising timeout to non-zero && <=180, the LIMITED_DISC_MODE will return NRF_SUCCESS.

2. Leaving it at LIMITED_DISC_MODE should be fine.

3. As far as I know, the current consumption won't be affected by what advertising flag you set.

Best regards,

Simon

[Nikosant03]

Thank you Simon,

Now is clear to me