Merge pull request #3 from top-gun/1.3-wifi-optimized

1.3 wifi optimized

Wemos/Sensor04-Truebner-SMT50.ino

@@ -4,15 +4,24 @@
 #include <Adafruit_ADS1015.h>
 
 // Update these with values suitable for your network.
-const char* ssid = "xxxxwifiname";
-const char* password = "secretpassword";
+const char* ssid = "xxxxxx";
+const char* password = "yyyyyyyy";
 const char* mqtt_server = "192.168.178.37";
 
 // DS-Intervall is one minute in Mikroseconds, needed for the calculation of the Deep Sleep between measurements
 const uint32_t DS_Intervall = 60*1000000;
 // Minuten is the Deep Sleep-time between measurements
 uint32_t Minuten = 30;
 
+// The ESP8266 RTC memory is arranged into blocks of 4 bytes. The access methods read and write 4 bytes at a time,
+// so the RTC data structure should be padded to a 4-byte multiple.
+struct {
+  uint32_t crc32;   // 4 bytes
+  uint8_t channel;  // 1 byte,   5 in total
+  uint8_t bssid[6]; // 6 bytes, 11 in total
+  uint8_t padding;  // 1 byte,  12 in total
+} rtcData;
+
 // or use this for debugging purposes: 3 minutes
 //const uint32_t DS_Intervall = 3*60*1000000;
 
@@ -29,29 +38,82 @@ PubSubClient client(espClient);
 ADC_MODE(ADC_VCC);
 
 void setup_wifi() {
+
+// Use Wifi.config to manually configure the network. 
 // static address configuration. You can leave these out and use DHCP by using WiFi.begin() instead of WiFi.config
-//  IPAddress ip(192, 168, 178, 57);
-//  IPAddress gateway(192, 168, 178, 1);
-//  IPAddress subnet(255, 255, 255, 0);
-//  IPAddress dns(192, 168, 178, 1);
-
-// Use Wifi.config to manually configure the network. Use Wifi.begin() for DHCP-controlled network.
-//    WiFi.config(ip, dns, gateway, subnet);
-  WiFi.begin();
-
+  IPAddress ip(192, 168, 178, 57);
+  IPAddress gateway(192, 168, 178, 1);
+  IPAddress subnet(255, 255, 255, 0);
+  //IPAddress dns(192, 168, 178, 1);
+  WiFi.config(ip, gateway, subnet);  // we work locally and don't need DNS
+  //WiFi.config(ip, dns, gateway, subnet); // use this in case you use an external MQTT-service
+
+// Bring up the WiFi connection
+  WiFi.forceSleepWake();
+  delay( 1 );
+  WiFi.mode( WIFI_STA );
+
+// Try to read WiFi settings from RTC memory
+  bool rtcValid = false;
+  if( ESP.rtcUserMemoryRead( 0, (uint32_t*)&rtcData, sizeof( rtcData ) ) ) {
+  // Calculate the CRC of what we just read from RTC memory, but skip the first 4 bytes as that's the checksum itself.
+    uint32_t crc = calculateCRC32( ((uint8_t*)&rtcData) + 4, sizeof( rtcData ) - 4 );
+    if( crc == rtcData.crc32 ) {
+      rtcValid = true;
+    }
+  }
+
 // We start by connecting to a WiFi network
   Serial.print("Connecting to ");
   Serial.println(ssid);
-  WiFi.begin(ssid, password);
-  while (WiFi.status() != WL_CONNECTED) 
-  {
-    delay(500);
-    Serial.print(".");
+  if( rtcValid ) {
+    // The RTC data was good, make a quick connection
+    Serial.println("connecting with data from rtc memory");
+    WiFi.begin(ssid,password, rtcData.channel, rtcData.bssid, true );
+  }
+  else {
+    // The RTC data was not valid, so make a regular connection
+    Serial.println("connecting fresh, just SSID and password");
+    WiFi.begin(ssid,password);
+  }
+
+
+  int retries = 0;
+  int wifiStatus = WiFi.status();
+  while( wifiStatus != WL_CONNECTED ) {
+    retries++;
+    if( retries == 100 ) {
+      // Quick connect is not working, reset WiFi and try regular connection
+      Serial.println("Changing strategy, attemting fresh connection");
+      WiFi.disconnect();
+      delay( 10 );
+      WiFi.forceSleepBegin();
+      delay( 10 );
+      WiFi.forceSleepWake();
+      delay( 10 );
+      WiFi.begin(ssid,password);
+    }
+    if( retries == 600 ) {
+      // Giving up after 30 seconds and going back to sleep
+      Serial.println("Giving up after 30 seconds without success");
+      WiFi.disconnect( true );
+      delay( 1 );
+      WiFi.mode( WIFI_OFF );
+      ESP.deepSleep( Minuten * DS_Intervall, WAKE_RF_DISABLED );
+      return; // Not expecting this to be called, the previous call will never return.
+    }
+    delay( 50 );
+    wifiStatus = WiFi.status();
   }
   Serial.println("");
   Serial.println("WiFi connected");
   Serial.println("IP address: ");
   Serial.println(WiFi.localIP());
+  rtcData.channel = WiFi.channel();
+  memcpy( rtcData.bssid, WiFi.BSSID(), 6 ); // Copy 6 bytes of BSSID (AP's MAC address)
+  rtcData.crc32 = calculateCRC32( ((uint8_t*)&rtcData) + 4, sizeof( rtcData ) - 4 );
+  ESP.rtcUserMemoryWrite( 0, (uint32_t*)&rtcData, sizeof( rtcData ) );
+
 } // end of setup_wifi
 
 void callback(char* topic, byte* payload, unsigned int length) {
@@ -62,7 +124,6 @@ void callback(char* topic, byte* payload, unsigned int length) {
   for (int i = 0; i < length; i++) {
     Serial.print((char)payload[i]);
   }
-  Serial.println();
   String payloadname = String((char*)topic);
   if (payloadname == "Sensoren/Sensor03/Intervall") {
     payload[length] = '\0';
@@ -79,9 +140,37 @@ void callback(char* topic, byte* payload, unsigned int length) {
 
 } // end of callback
 
+uint32_t calculateCRC32( const uint8_t *data, size_t length ) {
+  uint32_t crc = 0xffffffff;
+  while( length-- ) {
+    uint8_t c = *data++;
+    for( uint32_t i = 0x80; i > 0; i >>= 1 ) {
+      bool bit = crc & 0x80000000;
+      if( c & i ) {
+        bit = !bit;
+      }
+
+      crc <<= 1;
+      if( bit ) {
+        crc ^= 0x04c11db7;
+      }
+    }
+  }
+
+  return crc;
+}
 
 void setup()
 {
+// Disable the WiFi persistence.  The ESP8266 will not load and save WiFi settings in the flash memory.
+  WiFi.persistent( false );
+  delay(1);  
+
+// turn off wifi to conserve power  
+  WiFi.mode( WIFI_OFF );
+  WiFi.forceSleepBegin();
+  delay( 1 );
+
   Serial.begin(74880);
   Serial.println("Truebner SMT50 Soil moisture sensor");
 
@@ -180,8 +269,7 @@ void setup()
   Serial.println("300ms pause to make sure the server has responded to MQTT subscription");
   delay(300);
 
-  //hope for MQTT-callback
-
+//hope for MQTT-callback
   client.loop();
 
 // MQTT disconnect
@@ -191,8 +279,9 @@ void setup()
   Serial.print(".");
   Serial.print("Jetzt Deep Sleep ");
   Serial.print(Minuten);
-  delay(10);
-  ESP.deepSleep(Minuten * DS_Intervall);  
+  WiFi.disconnect( true );
+  delay( 10 );
+  ESP.deepSleep(Minuten * DS_Intervall, WAKE_RF_DISABLED);  
   delay(100);
 }