Refine _bleio

This PR refines the _bleio API. It was originally motivated by
the addition of a new CircuitPython service that enables reading
and modifying files on the device. Moving the BLE lifecycle outside
of the VM motivated a number of changes to remove heap allocations
in some APIs.

It also motivated unifying connection initiation to the Adapter class
rather than the Central and Peripheral classes which have been removed.
Adapter now handles the GAP portion of BLE including advertising, which
has moved but is largely unchanged, and scanning, which has been enhanced
to return an iterator of filtered results.

Once a connection is created (either by us (aka Central) or a remote
device (aka Peripheral)) it is represented by a new Connection class.
This class knows the current connection state and can discover and
instantiate remote Services along with their Characteristics and
Descriptors.

Relates to #586

1 files changed, 5 insertions, 4 deletions

diff --git a/shared-bindings/_bleio/Descriptor.c b/shared-bindings/_bleio/Descriptor.c
index 0ab9fe8e9..45a95903e 100644
--- a/shared-bindings/_bleio/Descriptor.c
+++ b/shared-bindings/_bleio/Descriptor.c
@@ -46,9 +46,8 @@
 //|
 //|   There is no regular constructor for a Descriptor. A new local Descriptor can be created
 //|   and attached to a Characteristic by calling `add_to_characteristic()`.
-//|   Remote Descriptor objects are created by `Central.discover_remote_services()`
-//|   or `Peripheral.discover_remote_services()` as part of remote Characteristics
-//|   in the remote Services that are discovered.
+//|   Remote Descriptor objects are created by `Connection.discover_remote_services()`
+//|   as part of remote Characteristics in the remote Services that are discovered.
 //|
 //|   .. classmethod:: add_to_characteristic(characteristic, uuid, *, read_perm=`Attribute.OPEN`, write_perm=`Attribute.OPEN`, max_length=20, fixed_length=False, initial_value=b'')
 //|
@@ -180,7 +179,9 @@ const mp_obj_property_t bleio_descriptor_characteristic_obj = {
 STATIC mp_obj_t bleio_descriptor_get_value(mp_obj_t self_in) {
     bleio_descriptor_obj_t *self = MP_OBJ_TO_PTR(self_in);
 
-    return common_hal_bleio_descriptor_get_value(self);
+    uint8_t temp[512];
+    size_t actual_len = common_hal_bleio_descriptor_get_value(self, temp, sizeof(temp));
+    return mp_obj_new_bytearray(actual_len, temp);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(bleio_descriptor_get_value_obj, bleio_descriptor_get_value);