[esp32_ble_client] Fix connection parameter timing by setting preferences before connection (#10059)

esphome/components/esp32_ble_client/ble_client_base.cpp

@@ -145,6 +145,36 @@ void BLEClientBase::connect() {
            this->remote_addr_type_);
   this->paired_ = false;
 
+  // Set preferred connection parameters before connecting
+  // Use FAST for all V3 connections (better latency and reliability)
+  // Use MEDIUM for V1/legacy connections (balanced performance)
+  uint16_t min_interval, max_interval, timeout;
+  const char *param_type;
+
+  if (this->connection_type_ == espbt::ConnectionType::V3_WITHOUT_CACHE ||
+      this->connection_type_ == espbt::ConnectionType::V3_WITH_CACHE) {
+    min_interval = FAST_MIN_CONN_INTERVAL;
+    max_interval = FAST_MAX_CONN_INTERVAL;
+    timeout = FAST_CONN_TIMEOUT;
+    param_type = "fast";
+  } else {
+    min_interval = MEDIUM_MIN_CONN_INTERVAL;
+    max_interval = MEDIUM_MAX_CONN_INTERVAL;
+    timeout = MEDIUM_CONN_TIMEOUT;
+    param_type = "medium";
+  }
+
+  auto param_ret = esp_ble_gap_set_prefer_conn_params(this->remote_bda_, min_interval, max_interval,
+                                                      0,  // latency: 0
+                                                      timeout);
+  if (param_ret != ESP_OK) {
+    ESP_LOGW(TAG, "[%d] [%s] esp_ble_gap_set_prefer_conn_params failed: %d", this->connection_index_,
+             this->address_str_.c_str(), param_ret);
+  } else {
+    ESP_LOGD(TAG, "[%d] [%s] Set %s conn params", this->connection_index_, this->address_str_.c_str(), param_type);
+  }
+
+  // Now open the connection
   auto ret = esp_ble_gattc_open(this->gattc_if_, this->remote_bda_, this->remote_addr_type_, true);
   if (ret) {
     ESP_LOGW(TAG, "[%d] [%s] esp_ble_gattc_open error, status=%d", this->connection_index_, this->address_str_.c_str(),
@@ -152,35 +182,6 @@ void BLEClientBase::connect() {
     this->set_state(espbt::ClientState::IDLE);
   } else {
     this->set_state(espbt::ClientState::CONNECTING);
-
-    // Always set connection parameters to ensure stable operation
-    // Use FAST for all V3 connections (better latency and reliability)
-    // Use MEDIUM for V1/legacy connections (balanced performance)
-    uint16_t min_interval, max_interval, timeout;
-    const char *param_type;
-
-    if (this->connection_type_ == espbt::ConnectionType::V3_WITHOUT_CACHE ||
-        this->connection_type_ == espbt::ConnectionType::V3_WITH_CACHE) {
-      min_interval = FAST_MIN_CONN_INTERVAL;
-      max_interval = FAST_MAX_CONN_INTERVAL;
-      timeout = FAST_CONN_TIMEOUT;
-      param_type = "fast";
-    } else {
-      min_interval = MEDIUM_MIN_CONN_INTERVAL;
-      max_interval = MEDIUM_MAX_CONN_INTERVAL;
-      timeout = MEDIUM_CONN_TIMEOUT;
-      param_type = "medium";
-    }
-
-    auto param_ret = esp_ble_gap_set_prefer_conn_params(this->remote_bda_, min_interval, max_interval,
-                                                        0,  // latency: 0
-                                                        timeout);
-    if (param_ret != ESP_OK) {
-      ESP_LOGW(TAG, "[%d] [%s] esp_ble_gap_set_prefer_conn_params failed: %d", this->connection_index_,
-               this->address_str_.c_str(), param_ret);
-    } else {
-      ESP_LOGD(TAG, "[%d] [%s] Set %s conn params", this->connection_index_, this->address_str_.c_str(), param_type);
-    }
   }
 }
 
@@ -255,6 +256,19 @@ void BLEClientBase::log_event_(const char *name) {
   ESP_LOGD(TAG, "[%d] [%s] %s", this->connection_index_, this->address_str_.c_str(), name);
 }
 
+void BLEClientBase::restore_medium_conn_params_() {
+  // Restore to medium connection parameters after initial connection phase
+  // This balances performance with bandwidth usage for normal operation
+  esp_ble_conn_update_params_t conn_params = {{0}};
+  memcpy(conn_params.bda, this->remote_bda_, sizeof(esp_bd_addr_t));
+  conn_params.min_int = MEDIUM_MIN_CONN_INTERVAL;
+  conn_params.max_int = MEDIUM_MAX_CONN_INTERVAL;
+  conn_params.latency = 0;
+  conn_params.timeout = MEDIUM_CONN_TIMEOUT;
+  ESP_LOGD(TAG, "[%d] [%s] Restoring medium conn params", this->connection_index_, this->address_str_.c_str());
+  esp_ble_gap_update_conn_params(&conn_params);
+}
+
 bool BLEClientBase::gattc_event_handler(esp_gattc_cb_event_t event, esp_gatt_if_t esp_gattc_if,
                                         esp_ble_gattc_cb_param_t *param) {
   if (event == ESP_GATTC_REG_EVT && this->app_id != param->reg.app_id)
@@ -322,6 +336,10 @@ bool BLEClientBase::gattc_event_handler(esp_gattc_cb_event_t event, esp_gatt_if_
       ESP_LOGI(TAG, "[%d] [%s] Connection open", this->connection_index_, this->address_str_.c_str());
       if (this->connection_type_ == espbt::ConnectionType::V3_WITH_CACHE) {
         ESP_LOGI(TAG, "[%d] [%s] Using cached services", this->connection_index_, this->address_str_.c_str());
+
+        // Restore to medium connection parameters for cached connections too
+        this->restore_medium_conn_params_();
+
         // only set our state, subclients might have more stuff to do yet.
         this->state_ = espbt::ClientState::ESTABLISHED;
         break;
@@ -419,15 +437,7 @@ bool BLEClientBase::gattc_event_handler(esp_gattc_cb_event_t event, esp_gatt_if_
       // This balances performance with bandwidth usage after the critical discovery phase
       if (this->connection_type_ == espbt::ConnectionType::V3_WITHOUT_CACHE ||
           this->connection_type_ == espbt::ConnectionType::V3_WITH_CACHE) {
-        esp_ble_conn_update_params_t conn_params = {{0}};
+        this->restore_medium_conn_params_();
-        memcpy(conn_params.bda, this->remote_bda_, sizeof(esp_bd_addr_t));
-        conn_params.min_int = MEDIUM_MIN_CONN_INTERVAL;
-        conn_params.max_int = MEDIUM_MAX_CONN_INTERVAL;
-        conn_params.latency = 0;
-        conn_params.timeout = MEDIUM_CONN_TIMEOUT;
-        ESP_LOGD(TAG, "[%d] [%s] Restored medium conn params after service discovery", this->connection_index_,
-                 this->address_str_.c_str());
-        esp_ble_gap_update_conn_params(&conn_params);
       }
 
       this->state_ = espbt::ClientState::ESTABLISHED;

esphome/components/esp32_ble_client/ble_client_base.h

@@ -127,6 +127,7 @@ class BLEClientBase : public espbt::ESPBTClient, public Component {
   // 6 bytes used, 2 bytes padding
 
   void log_event_(const char *name);
+  void restore_medium_conn_params_();
 };
 
 }  // namespace esp32_ble_client