Switching from BLE_ADV_EVT_SLOW to BLE_ADV_EVT_FAST not working

[jtredez]

Hi,

I use S130 with SDK 12.3.0.

I have an application that permanently advertise with an interval of 10s but when the user push a button I switch to BLE_ADV_EVT_FAST . I use the ble_advertising module.

To switch to fast mode I call ble_advertising_start(BLE_ADV_MODE_FAST) when the button is pressed but I never receive the BLE_ADV_EVT_FAST on the _OnAdvEvt function.

My configuration is:

#define APP_ADV_FAST_INTERVAL           64                                         // Fast advertising interval (multiple of 0.625 ms) = 40 ms
#define APP_ADV_FAST_TIMEOUT_IN_SECONDS 2                                          // Fast advertising timeout = 2s
#define APP_ADV_SLOW_INTERVAL           16000                                      // Slow advertising interval (multiple of 0.625 ms) = 10s
#define APP_ADV_SLOW_TIMEOUT_IN_SECONDS 0                                          // Slow advertising timeout = 1mn

static void _AdvertisingInit(void)
{
    uint32_t u32_ErrCode;
    ble_advdata_t s_AdvData;
    ble_adv_modes_config_t s_Options;

    // Build advertising data struct to pass into @ref ble_advertising_init.
    memset(&s_AdvData, 0, sizeof(s_AdvData));
    s_AdvData.name_type               = BLE_ADVDATA_FULL_NAME;
    s_AdvData.include_appearance      = true;
    s_AdvData.flags                   = BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE;        //BLE_GAP_ADV_FLAGS_LE_ONLY_LIMITED_DISC_MODE;

    memset(&s_Options, 0, sizeof(s_Options));
    s_Options.ble_adv_fast_enabled  = true;
    s_Options.ble_adv_fast_interval = APP_ADV_FAST_INTERVAL;
    s_Options.ble_adv_fast_timeout  = APP_ADV_FAST_TIMEOUT_IN_SECONDS;
    s_Options.ble_adv_slow_enabled  = true;
    s_Options.ble_adv_slow_interval = APP_ADV_SLOW_INTERVAL;
    s_Options.ble_adv_slow_timeout  = APP_ADV_SLOW_TIMEOUT_IN_SECONDS;

    u32_ErrCode = ble_advertising_init(&s_AdvData, NULL, &s_Options, _OnAdvEvt, NULL);
    APP_ERROR_CHECK(u32_ErrCode);
}


I did another try with a APP_ADV_SLOW_TIMOUT_IN_SECONDS set to 60. I have the sequence FAST->SLOW->IDLE and when I receive the BLE_ADV_EVT_IDLE I do a ble_advertising_start(BLE_ADV_MODE_SLOW), it restart in slow mode. But when the user push the button it's not possible to switch to fast mode.

Best regards.

[FormerMember]

When you push the button to start fast advertising, is the advertising interval changed? (You can check it using nRF Connect (Android, maybe iOS as well) )

Could you do the following:

1. Set a breakpoint at ble_advertising_start(BLE_ADV_MODE_FAST).
2. Run the chip in debug mode.
3. Press the button to switch to fast advertsing:  step through the code in ble_advertising_start(), and check if the "behavior" is as expected.

[jtredez]

Scanning with nRFConnect (android) show me strange thing on interval timing:

Advertising type: Legacy (Adv Interval N/A)
16:36:18.541
10000ms
Advertising type: Legacy (Adv Interval 41ms)
16:36:08.540
20005ms
16:35:48.534
9999ms
16:35:38.535
60026ms
16:34:38.508
92ms
+ 21 more
249ms
16:34:36.573

Step through code when pushing the button give me a return=8 (invalide state?) from the function sd_ble_gap_adv_start() in ble_advertising_start().

Remark: it's not easy to step by step because frequently I'm finish to the app_error_save_and_stop() function with an id=1 and pc=0x104AE, info=0

[jtredez]

On nRF Connect:

Device type: LE only
Advertising type: Legacy
Flags: GeneralDiscoverable, BrEdrNotSupported

I can connect when I am in FAST mode but in SLOW mode is not possible

[run_ar]

If you are using an advertising interval of 10s it could take a very long time to connect. Worst case the scan interval might match the advertisement interval in such a way the scanner will newer receive an advertisement packet. For how long have you been waiting before you have concluded that you cannot connect in SLOW mode?

[jtredez]

Sorry for the delay, I have just returned from vacation.

I use the Android nrfConnect and it timeout after 30s.

[run_ar]

That means you only have about 3 advertisement events before the scanner times out. Not sure about the scan window and scan interval used by the phone you are using, but I would not expect the scanner to establish a connection after only 3 advertisement events. I did an experiment with iOS some years ago an with very short advertisement intervals I could get a hit within 3 events, but for slower intervals (I stopped at 1 second) it  would take 20+ events. However this does depend a lot on the combination of advertisement interval and scan interval / scan window. See picture below for example.

[jtredez]

Ok thank you