RE: NRF_SDH_BLE_OBSERVER and other questions, including macro clarification

Andy — Wed, 24 Apr 2019 10:35:23 GMT

Happy to help :)

RE: NRF_SDH_BLE_OBSERVER and other questions, including macro clarification

DiBosco — Wed, 24 Apr 2019 10:11:54 GMT

Thanks Andy, that's helpful. As I was drifting off to sleep last night it suddenly hit me that I should have run the preprocessor on main.c not my file and sure enough I can see the expanded macro there.

The other question was about what an observer is, which you kindly answered. Thanks again.

RE: NRF_SDH_BLE_OBSERVER and other questions, including macro clarification

Andy — Tue, 23 Apr 2019 18:02:00 GMT

[quote userid="79197" url="~/f/nordic-q-a/46522/nrf_sdh_ble_observer-and-other-questions-including-macro-clarification"]what, exactly, is this observer thing please?[/quote]

I can't tell you exactly what it is because I don't understand it fully myself, but -in a nutshell- it declares a function that will be called whenever a BLE event happens. The linker file specifies some memory sections and the softdevice somehow refers to these sections internally.

This macro:

NRF_SDH_BLE_OBSERVER(m_ble_observer, APP_BLE_OBSERVER_PRIO, ble_evt_handler, NULL);

expands to this:

static_assert(1, "NRF_SDH_BLE_ENABLED not set!");                                 \
static_assert(3 < 4, "Priority level unavailable.");             \
static nrf_sdh_ble_evt_observer_t m_ble_observer __attribute__ ((section("." "sdh_ble_observers3"))) __attribute__((used)) =  \
{                                                                                                   \
    .handler   = ble_evt_handler,                                                                          \
    .p_context = ((void *)0)                                                                           \
}

Which as far as I understand it just puts a struct in a specific section in memory.

[quote userid="79197" url="~/f/nordic-q-a/46522/nrf_sdh_ble_observer-and-other-questions-including-macro-clarification"]Oh and one more thing, I see this "soft device" term used, what is that please?[/quote]

The softdevice is just how Nordic calls its radio stack. It comes as a precompiled hex file and needs to be flashed together with the application if you want to use any radio functionality.

[quote userid="79197" url="~/f/nordic-q-a/46522/nrf_sdh_ble_observer-and-other-questions-including-macro-clarification"]So the other question is[/quote]

What was the other question?