reset HVC state before sending indication to prevent stale signals

Author: hathach

libraries/Bluefruit52Lib/src/BLECharacteristic.cpp

@@ -874,7 +874,9 @@ bool BLECharacteristic::indicate(uint16_t conn_hdl, const void* data, uint16_t l
 
       LOG_LV2("CHR", "Indicate %d bytes", packet_len);
 
-      // Blocking wait until receiving confirmation from peer
+      // Blocking wait until receiving confirmation from peer.
+      // Reset HVC state BEFORE hvx() so a fast HVC event isn't drained as stale.
+      VERIFY ( conn->prepareForIndicateConfirm() );
       VERIFY_STATUS( sd_ble_gatts_hvx(conn_hdl, &hvx_params), false );
       VERIFY ( conn->waitForIndicateConfirm() );
 

libraries/Bluefruit52Lib/src/BLEConnection.cpp

@@ -56,11 +56,11 @@ BLEConnection::BLEConnection(uint16_t conn_hdl, ble_gap_evt_connected_t const* e
 
   _hvn_sem   = xSemaphoreCreateCounting(hvn_qsize, hvn_qsize);
   _wrcmd_sem = xSemaphoreCreateCounting(wrcmd_qsize, wrcmd_qsize);
+  _hvc_sem   = xSemaphoreCreateBinary();
 
   _sec_mode.sm = _sec_mode.lv = 1; // default to open
 
   _bonded = false;
-  _hvc_sem = NULL;
   _hvc_received = false;
 
   _ediv = 0xFFFF;
@@ -70,11 +70,9 @@ BLEConnection::BLEConnection(uint16_t conn_hdl, ble_gap_evt_connected_t const* e
 
 BLEConnection::~BLEConnection()
 {
-  vSemaphoreDelete( _hvn_sem );
-  vSemaphoreDelete( _wrcmd_sem );
-
-  //------------- on-the-fly data must be freed -------------//
-  if (_hvc_sem  ) vSemaphoreDelete(_hvc_sem );
+  vSemaphoreDelete(_hvn_sem);
+  vSemaphoreDelete(_wrcmd_sem);
+  vSemaphoreDelete(_hvc_sem);
 }
 
 uint16_t BLEConnection::handle (void)
@@ -289,25 +287,22 @@ bool BLEConnection::requestPairing(void)
 
 void BLEConnection::setIndicateConfirmTimeout(uint32_t timeout_ms)
 {
-  _indicate_confirm_timeout = (timeout_ms == portMAX_DELAY) ? portMAX_DELAY : pdMS_TO_TICKS(timeout_ms);
+  _indicate_confirm_timeout = (timeout_ms == UINT32_MAX) ? portMAX_DELAY : pdMS_TO_TICKS(timeout_ms);
 }
 
-bool BLEConnection::waitForIndicateConfirm(void)
+// Must be called BEFORE sd_ble_gatts_hvx() to clear any stale HVC state from a
+// previous indication (e.g. a late HVC that arrived after a timeout). Pairs with
+// waitForIndicateConfirm().
+bool BLEConnection::prepareForIndicateConfirm(void)
 {
-  // Lazy-allocate once per connection and reuse. Avoids a create/delete race
-  // with the BLE event handler that may give the semaphore on HVC/timeout.
-  if (_hvc_sem == NULL)
-  {
-    _hvc_sem = xSemaphoreCreateBinary();
-    if (_hvc_sem == NULL) return false;
-  }
-
-  // Drain any stale signal left from a previous call (e.g. late HVC after timeout)
   xSemaphoreTake(_hvc_sem, 0);
-
   _hvc_received = false;
-  xSemaphoreTake(_hvc_sem, _indicate_confirm_timeout);
+  return true;
+}
 
+bool BLEConnection::waitForIndicateConfirm(void)
+{
+  xSemaphoreTake(_hvc_sem, _indicate_confirm_timeout);
   return _hvc_received;
 }
 
@@ -440,7 +435,7 @@ void BLEConnection::_eventHandler(ble_evt_t* evt)
       LOG_LV2("GATTS", "Confirm received handle = 0x%04X", evt->evt.gatts_evt.params.hvc.handle);
 
       _hvc_received = true;
-      if ( _hvc_sem ) xSemaphoreGive(_hvc_sem);
+      xSemaphoreGive(_hvc_sem);
     }
     break;
 
@@ -452,7 +447,7 @@ void BLEConnection::_eventHandler(ble_evt_t* evt)
       if (BLE_GATT_TIMEOUT_SRC_PROTOCOL == timeout_src)
       {
         _hvc_received = false;
-        if ( _hvc_sem ) xSemaphoreGive(_hvc_sem);
+        xSemaphoreGive(_hvc_sem);
       }
     }
     break;

libraries/Bluefruit52Lib/src/BLEConnection.h

@@ -66,8 +66,6 @@ class BLEConnection
 
     SemaphoreHandle_t _hvn_sem;
     SemaphoreHandle_t _wrcmd_sem;
-
-    // On-demand semaphore/data that are created on the fly
     SemaphoreHandle_t _hvc_sem;
 
     TickType_t _indicate_confirm_timeout;
@@ -112,6 +110,7 @@ class BLEConnection
     bool getHvnPacket(void);
     bool releaseHvnPacket(void);
     bool getWriteCmdPacket(void);
+    bool prepareForIndicateConfirm(void);
     bool waitForIndicateConfirm(void);
 
     bool saveBondKey(bond_keys_t const* ltkey);