fixed aliot connection check interval issue

esp8285/lib/AliyunIoTSDK/src/AliyunIoTSDK.cpp

@@ -211,9 +211,10 @@ int AliyunIoTSDK::begin(PubSubClient &mqtt_client,
 int AliyunIoTSDK::loop() {
     int mqttStatus = 0;
     client->loop();
-    if (millis() - lastMs >= CHECK_INTERVAL) {
-        lastMs = millis();
+    unsigned long thisMs = millis();
+    if (thisMs - lastMs >= CHECK_INTERVAL) {
         mqttStatus = mqttCheckConnect();
+        lastMs = thisMs;
     }
 
     if (0 == mqttStatus) {

esp8285/src/aliot_client.cpp

@@ -58,7 +58,7 @@ int connectToAliot(PubSubClient& mqtt_client) {
     String aliot_client_id = g_product_key + "." + g_device_name;
 
     int res = iot.begin(mqtt_client, g_product_key.c_str(), g_device_name.c_str(), g_device_token.c_str(), g_aliot_region.c_str());
-    if (0 == res) {
+    if (0 == res && mqtt_client.connected()) {
         INFOF("Aliyun IoT connected\n");
     } else {
         ERRORF("Failed to connect to Aliyun IoT\n");

esp8285/src/iot_hub.cpp

@@ -142,6 +142,7 @@ void keepAliveIot() {
             g_mqtt_client.unsubscribe(g_downstream_topic.c_str());
             g_subscribed = false;
             connectIot();
+            last_check_time = current_time;
         }
     }
 }