diff --git a/extmod/modbluetooth.c b/extmod/modbluetooth.c
index e379a8c6a304c..2d22c17dc900b 100644
--- a/extmod/modbluetooth.c
+++ b/extmod/modbluetooth.c
@@ -66,9 +66,12 @@
 typedef struct {
     mp_obj_base_t base;
     mp_obj_t irq_handler;
+    mp_obj_t irq_data_tuple;
+    #if MICROPY_PY_BLUETOOTH_IRQ_CAN_BE_ON_SEPARATE_THREAD
+    mp_obj_t irq_event;
+    #endif
     #if !MICROPY_PY_BLUETOOTH_USE_SYNC_EVENTS
     bool irq_scheduled;
-    mp_obj_t irq_data_tuple;
     uint8_t irq_data_addr_bytes[6];
     uint16_t irq_data_data_alloc;
     mp_obj_array_t irq_data_addr;
@@ -260,10 +263,10 @@ STATIC mp_obj_t bluetooth_ble_make_new(const mp_obj_type_t *type, size_t n_args,
 
         o->irq_handler = mp_const_none;
 
-        #if !MICROPY_PY_BLUETOOTH_USE_SYNC_EVENTS
         // Pre-allocate the event data tuple to prevent needing to allocate in the IRQ handler.
         o->irq_data_tuple = mp_obj_new_tuple(MICROPY_PY_BLUETOOTH_MAX_EVENT_DATA_TUPLE_LEN, NULL);
 
+        #if !MICROPY_PY_BLUETOOTH_USE_SYNC_EVENTS
         // Pre-allocated buffers for address, payload and uuid.
         mp_obj_memoryview_init(&o->irq_data_addr, 'B', 0, 0, o->irq_data_addr_bytes);
         o->irq_data_data_alloc = MICROPY_PY_BLUETOOTH_MAX_EVENT_DATA_BYTES_LEN(MICROPY_PY_BLUETOOTH_RINGBUF_SIZE);
@@ -274,6 +277,10 @@ STATIC mp_obj_t bluetooth_ble_make_new(const mp_obj_type_t *type, size_t n_args,
         ringbuf_alloc(&o->ringbuf, MICROPY_PY_BLUETOOTH_RINGBUF_SIZE);
         #endif
 
+        #if MICROPY_PY_BLUETOOTH_IRQ_CAN_BE_ON_SEPARATE_THREAD
+        mp_bluetooth_port_sync_init();
+        #endif
+
         MP_STATE_VM(bluetooth) = MP_OBJ_FROM_PTR(o);
     }
     return MP_STATE_VM(bluetooth);
@@ -1111,6 +1118,16 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_1(bluetooth_ble_invoke_irq_obj, bluetooth_ble_inv
 
 #if MICROPY_PY_BLUETOOTH_USE_SYNC_EVENTS
 
+#if MICROPY_PY_BLUETOOTH_IRQ_CAN_BE_ON_SEPARATE_THREAD
+STATIC mp_obj_t bluetooth_ble_invoke_irq(mp_obj_t bluetooth_in) {
+    mp_obj_bluetooth_ble_t *o = MP_OBJ_TO_PTR(bluetooth_in);
+    o->irq_event = mp_call_function_2(o->irq_handler, o->irq_event, o->irq_data_tuple);
+    mp_bluetooth_port_sync_signal_done();
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(bluetooth_ble_invoke_irq_obj, bluetooth_ble_invoke_irq);
+#endif
+
 STATIC mp_obj_t invoke_irq_handler(uint16_t event,
     const mp_int_t *numeric, size_t n_unsigned, size_t n_signed,
     const uint8_t *addr,
@@ -1125,8 +1142,7 @@ STATIC mp_obj_t invoke_irq_handler(uint16_t event,
     mp_obj_array_t mv_data[2];
     assert(n_data <= 2);
 
-    mp_obj_tuple_t *data_tuple = mp_local_alloc(sizeof(mp_obj_tuple_t) + sizeof(mp_obj_t) * MICROPY_PY_BLUETOOTH_MAX_EVENT_DATA_TUPLE_LEN);
-    data_tuple->base.type = &mp_type_tuple;
+    mp_obj_tuple_t *data_tuple = MP_OBJ_TO_PTR(o->irq_data_tuple);
     data_tuple->len = 0;
 
     for (size_t i = 0; i < n_unsigned; ++i) {
@@ -1154,11 +1170,18 @@ STATIC mp_obj_t invoke_irq_handler(uint16_t event,
     }
     assert(data_tuple->len <= MICROPY_PY_BLUETOOTH_MAX_EVENT_DATA_TUPLE_LEN);
 
-    mp_obj_t result = mp_call_function_2(o->irq_handler, MP_OBJ_NEW_SMALL_INT(event), MP_OBJ_FROM_PTR(data_tuple));
-
-    mp_local_free(data_tuple);
+    #if MICROPY_PY_BLUETOOTH_IRQ_CAN_BE_ON_SEPARATE_THREAD
+    if (!mp_bluetooth_port_sync_is_main_thread()) {
+        o->irq_event = MP_OBJ_NEW_SMALL_INT(event);
+        while (!mp_sched_schedule(MP_OBJ_FROM_PTR(&bluetooth_ble_invoke_irq_obj), MP_OBJ_FROM_PTR(o))) {
+            mp_bluetooth_port_sync_yield();
+        }
+        mp_bluetooth_port_sync_wait_for_signal();
+        return o->irq_event;
+    }
+    #endif
 
-    return result;
+    return mp_call_function_2(o->irq_handler, MP_OBJ_NEW_SMALL_INT(event), MP_OBJ_FROM_PTR(data_tuple));
 }
 
 #define NULL_NUMERIC NULL
diff --git a/extmod/modbluetooth.h b/extmod/modbluetooth.h
index d126ad6c11344..9c5fb6725d09c 100644
--- a/extmod/modbluetooth.h
+++ b/extmod/modbluetooth.h
@@ -405,6 +405,14 @@ int mp_bluetooth_l2cap_recvinto(uint16_t conn_handle, uint16_t cid, uint8_t *buf
 int mp_bluetooth_hci_cmd(uint16_t ogf, uint16_t ocf, const uint8_t *req, size_t req_len, uint8_t *resp, size_t resp_len, uint8_t *status);
 #endif // MICROPY_PY_BLUETOOTH_ENABLE_HCI_CMD
 
+#if MICROPY_PY_BLUETOOTH_IRQ_CAN_BE_ON_SEPARATE_THREAD
+void mp_bluetooth_port_sync_init(void);
+bool mp_bluetooth_port_sync_is_main_thread(void);
+void mp_bluetooth_port_sync_yield(void);
+void mp_bluetooth_port_sync_wait_for_signal(void);
+void mp_bluetooth_port_sync_signal_done(void);
+#endif
+
 /////////////////////////////////////////////////////////////////////////////
 // API implemented by modbluetooth (called by port-specific implementations):
 
diff --git a/extmod/nimble/modbluetooth_nimble.c b/extmod/nimble/modbluetooth_nimble.c
index e3a2f872e5ecb..f653b95d3e699 100644
--- a/extmod/nimble/modbluetooth_nimble.c
+++ b/extmod/nimble/modbluetooth_nimble.c
@@ -1791,9 +1791,9 @@ STATIC int ble_store_ram_read(int obj_type, const union ble_store_key *key, unio
         case BLE_STORE_OBJ_TYPE_OUR_SEC: {
             // <type=our,addr,ediv_rand>
             // Find our secret for this remote device, matching this ediv/rand key.
-            assert(ble_addr_cmp(&key->sec.peer_addr, BLE_ADDR_ANY)); // Must have address.
+            // TODO: Support cases where key->sec.peer_addr is BLE_ADDR_ANY, and
+            // key->sec.ediv_rand_present is false.
             assert(key->sec.idx == 0);
-            assert(key->sec.ediv_rand_present);
             key_data = (const uint8_t *)&key->sec.peer_addr;
             key_data_len = sizeof(ble_addr_t);
             break;
diff --git a/ports/esp32/main/CMakeLists.txt b/ports/esp32/main/CMakeLists.txt
index 656045da90a21..3c3c723138de4 100644
--- a/ports/esp32/main/CMakeLists.txt
+++ b/ports/esp32/main/CMakeLists.txt
@@ -172,11 +172,15 @@ target_compile_options(${MICROPY_TARGET} PUBLIC
     -Wno-missing-field-initializers
 )
 
+# Additional include directories needed for private NimBLE headers.
+target_include_directories(${MICROPY_TARGET} PUBLIC
+    ${IDF_PATH}/components/bt/host/nimble/nimble
+)
+
 # Add additional extmod and usermod components.
 target_link_libraries(${MICROPY_TARGET} micropy_extmod_btree)
 target_link_libraries(${MICROPY_TARGET} usermod)
 
-
 # Collect all of the include directories and compile definitions for the IDF components.
 foreach(comp ${IDF_COMPONENTS})
     micropy_gather_target_properties(__idf_${comp})
diff --git a/ports/esp32/mpconfigport.h b/ports/esp32/mpconfigport.h
index 8788963cb3209..b6eb9adf3f33c 100644
--- a/ports/esp32/mpconfigport.h
+++ b/ports/esp32/mpconfigport.h
@@ -124,7 +124,10 @@
 // extended modules
 #ifndef MICROPY_PY_BLUETOOTH
 #define MICROPY_PY_BLUETOOTH                (1)
+#define MICROPY_PY_BLUETOOTH_USE_SYNC_EVENTS (1)
+#define MICROPY_PY_BLUETOOTH_IRQ_CAN_BE_ON_SEPARATE_THREAD (1)
 #define MICROPY_PY_BLUETOOTH_ENABLE_CENTRAL_MODE (1)
+#define MICROPY_PY_BLUETOOTH_ENABLE_PAIRING_BONDING (1)
 #define MICROPY_BLUETOOTH_NIMBLE            (1)
 #define MICROPY_BLUETOOTH_NIMBLE_BINDINGS_ONLY (1)
 #endif
diff --git a/ports/esp32/mphalport.c b/ports/esp32/mphalport.c
index cf668216df9e3..8d077c5293508 100644
--- a/ports/esp32/mphalport.c
+++ b/ports/esp32/mphalport.c
@@ -213,3 +213,28 @@ void mp_hal_wake_main_task_from_isr(void) {
         portYIELD_FROM_ISR();
     }
 }
+
+/******************************************************************************/
+// Bluetooth event synchronisation helpers.
+
+SemaphoreHandle_t mp_bluetooth_port_sync_sem;
+
+void mp_bluetooth_port_sync_init(void) {
+    mp_bluetooth_port_sync_sem = xSemaphoreCreateBinary();
+}
+
+bool mp_bluetooth_port_sync_is_main_thread(void) {
+    return xTaskGetCurrentTaskHandle() == mp_main_task_handle;
+}
+
+void mp_bluetooth_port_sync_yield(void) {
+    vPortYield();
+}
+
+void mp_bluetooth_port_sync_wait_for_signal(void) {
+    xSemaphoreTake(mp_bluetooth_port_sync_sem, portMAX_DELAY);
+}
+
+void mp_bluetooth_port_sync_signal_done(void) {
+    xSemaphoreGive(mp_bluetooth_port_sync_sem);
+}