Hi Pritish,
On Thu, Apr 27, 2017 at 03:49:34PM -0700, Pritish Gandhi wrote:
> Hi All,
> I have a generic question about the nimBLE capabilities. I'm trying to
> build a BLE GATT server which has a set of services (say services A and B).
> However, these services need to be registered dynamically. What I mean is
> that when I boot up I won't know which services I need to register with the
> GATT server. I'd like to boot up, probe around a bit, and then make a
> decision on whether I want to register and then advertise either service A
> only, service B only, or both.
>
> However I'm not quite sure I see a way to do that. It seems like services
> need to be added and registered before the os runs.
>
> Here's what the comment says in ble_gatts.c
> /**
> * Queues a set of service definitions for registration. All services
> queued
> * in this manner get registered when ble_hs_init() is called.
> *
> * @param svcs An array of service definitions to queue for
> * registration. This array must be
> * terminated with an entry whose 'type'
> * equals 0.
> *
> * @return 0 on success;
> * BLE_HS_ENOMEM on heap exhaustion.
> */
>
> Is what I'm expecting to do not possible?
What you're expecting is almost possible, but it is not a use case that
the host API allows. The issue is that host starts itself as soon as
the OS is started, at which point it is too late to register additional
GATT services.
There is a fairly simple hack that I believe should make this possible:
1. Modify ble_hs_event_start() (ble_hs.c) such that it is a no-op:
--- a/net/nimble/host/src/ble_hs.c
+++ b/net/nimble/host/src/ble_hs.c
@@ -388,10 +388,12 @@ ble_hs_event_reset(struct os_event *ev)
static void
ble_hs_event_start(struct os_event *ev)
{
+#if 0
int rc;
rc = ble_hs_start();
assert(rc == 0);
+#endif
}
2. Call ble_hs_start() from your application after you have finished
registering services.
This seems like a pretty useful behavior, so it might be worth making
this configurable in future versions.
Chris
