tests/multi_bluetooth: Synchronise MTU exchange in BLE MTU tests.

dpgeorge · dpgeorge · commit d7ba279c36ae · 2025-07-20T22:03:05.000+10:00
Signed-off-by: Damien George &lt;damien@micropython.org&gt;
diff --git a/tests/multi_bluetooth/ble_mtu.py b/tests/multi_bluetooth/ble_mtu.py
@@ -106,6 +106,9 @@ def instance0():
             # Wait for central to connect to us.
             conn_handle = wait_for_event(_IRQ_CENTRAL_CONNECT, TIMEOUT_MS)
 
+            # Inform the central that we have been connected to.
+            multitest.broadcast("peripheral is connected")
+
             mtu = wait_for_event(_IRQ_MTU_EXCHANGED, TIMEOUT_MS)
 
             multitest.wait(f"client:discovery:{i}")
@@ -138,6 +141,13 @@ def instance1():
             ble.gap_connect(BDADDR[0], BDADDR[1], TIMEOUT_MS)
             conn_handle = wait_for_event(_IRQ_PERIPHERAL_CONNECT, TIMEOUT_MS)
 
+            # Wait for peripheral to be ready for MTU exchange.
+            # On ESP32 with NimBLE and IDF 5.4.2 (at least), if the MTU exchange occurs
+            # immediately after the peripheral connect event, the peripheral may see its
+            # _IRQ_MTU_EXCHANGED event before its _IRQ_CENTRAL_CONNECT event.  The wait
+            # here ensures correct event ordering on the peripheral.
+            multitest.wait("peripheral is connected")
+
             # Central-initiated mtu exchange.
             print("gattc_exchange_mtu")
             ble.gattc_exchange_mtu(conn_handle)
diff --git a/tests/multi_bluetooth/ble_mtu_peripheral.py b/tests/multi_bluetooth/ble_mtu_peripheral.py
@@ -101,6 +101,13 @@ def instance0():
             # Wait for central to connect to us.
             conn_handle = wait_for_event(_IRQ_CENTRAL_CONNECT, TIMEOUT_MS)
 
+            # Wait for central to be ready for MTU exchange.
+            # On ESP32 with NimBLE and IDF 5.4.2 (at least), if the MTU exchange occurs
+            # immediately after the central connect event, the central may see its
+            # _IRQ_MTU_EXCHANGED event before its _IRQ_PERIPHERAL_CONNECT event.  The
+            # wait here ensures correct event ordering on the central.
+            multitest.wait("central is connected")
+
             # Peripheral-initiated mtu exchange.
             print("gattc_exchange_mtu")
             ble.gattc_exchange_mtu(conn_handle)
@@ -142,6 +149,9 @@ def instance1():
             ble.gap_connect(BDADDR[0], BDADDR[1], 5000)
             conn_handle = wait_for_event(_IRQ_PERIPHERAL_CONNECT, TIMEOUT_MS)
 
+            # Inform the peripheral that we have been connected to.
+            multitest.broadcast("central is connected")
+
             mtu = wait_for_event(_IRQ_MTU_EXCHANGED, TIMEOUT_MS)
 
             print("gattc_discover_characteristics")
