diff --git a/platformio.ini b/platformio.ini
index 0074e59..1995297 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -12,6 +12,7 @@
 platform = espressif32
 board = wt32-eth01
 framework = arduino
+board_build.f_cpu = 240000000L
 lib_deps = siwats/ESPMegaPROR3@^1.3.0
            knolleary/PubSubClient@^2.8
            ivanseidel/ArduinoThread@^2.1.1
diff --git a/src/espmega_iot_core.cpp b/src/espmega_iot_core.cpp
index 84e0817..0ff5efc 100644
--- a/src/espmega_iot_core.cpp
+++ b/src/espmega_iot_core.cpp
@@ -19,7 +19,6 @@ uint16_t MQTT_PORT = 0;
 WebServer otaserver(80);
 #endif
 bool standalone = true;
-// #define MQTT_BASE_TOPIC "/espmega/ProR3"
 char MQTT_BASE_TOPIC[20];
 uint8_t base_topic_length = 0;
 char STATE_REQUEST_TOPIC[40];
@@ -104,8 +103,7 @@ char PWM_VALUE_TOPIC[75];
 char INPUTS_TOPIC[75];
 
 WiFiClient eth;
-PubSubClient mqtt_client(MQTT_SERVER, 1883, eth);
-PubSubClientTools mqtt(mqtt_client);
+PubSubClient mqtt(MQTT_SERVER, 1883, eth);
 
 #ifdef ENABLE_CLIMATE_MODULE
 DHTNEW env_sensor(DHT22_PIN);
@@ -159,8 +157,9 @@ void setup()
   lcd_send_command("boot_state.txt=\"Network Initializing . . .\"");
   network_begin();
   lcd_send_command("boot_state.txt=\"IoT Core Initializing . . .\"");
-  mqtt_client.setSocketTimeout(1000);
+  mqtt.setSocketTimeout(1000);
   eth.setTimeout(1);
+  mqtt.setCallback(&mqtt_callback);
   mqtt_connect();
   lcd_send_command("boot_state.txt=\"Threads Initializing . . .\"");
   thread_initialization();
@@ -176,7 +175,7 @@ void setup()
 void loop()
 {
   virtual_interrupt_loop();
-  mqtt_client.loop();
+  mqtt.loop();
   ESPMega_loop();
 #ifdef ENABLE_IR_MODULE
   ir_loop();
@@ -243,7 +242,7 @@ void eeprom_retrieve_init()
   eeprom_mqtt_useauth_retrieve();
   eeprom_mqtt_username_retrieve();
   eeprom_mqtt_password_retrieve();
-  mqtt_client.setServer(MQTT_SERVER, MQTT_PORT);
+  mqtt.setServer(MQTT_SERVER, MQTT_PORT);
   eeprom_basetopic_retrieve();
   base_topic_length = strlen(MQTT_BASE_TOPIC) + 1;
   memcpy(STATE_REQUEST_TOPIC, MQTT_BASE_TOPIC, 20);
@@ -465,15 +464,15 @@ void network_begin()
 
 void mqtt_connect()
 {
-  if (!mqtt_client.connected())
+  if (!mqtt.connected())
   {
     Serial.print("MQTT not connected, connecting . . .\n");
     lcd_send_stop_bit();
     if (MQTT_USE_AUTH)
-      mqtt_client.connect(HOSTNAME, MQTT_USERNAME, MQTT_PASSWORD);
+      mqtt.connect(HOSTNAME, MQTT_USERNAME, MQTT_PASSWORD);
     else
-      mqtt_client.connect(HOSTNAME);
-    if (mqtt_client.connected())
+      mqtt.connect(HOSTNAME);
+    if (mqtt.connected())
     {
       mqtt_subscribe();
       Serial.print("MQTT connected\n");
@@ -509,15 +508,40 @@ void mqtt_subscribe()
     PWM_SET_VALUE_TOPIC[base_topic_length + 5] = (i % 10) + '0';
     PWM_SET_STATE_TOPIC[base_topic_length + 4] = ((i - i % 10) / 10) + '0';
     PWM_SET_STATE_TOPIC[base_topic_length + 5] = (i % 10) + '0';
-    mqtt.subscribe(PWM_SET_STATE_TOPIC, pwm_state_callback);
-    mqtt.subscribe(PWM_SET_VALUE_TOPIC, pwm_value_callback);
+    mqtt.subscribe(PWM_SET_STATE_TOPIC);
+    mqtt.subscribe(PWM_SET_VALUE_TOPIC);
   }
 #ifdef ENABLE_CLIMATE_MODULE
-  mqtt.subscribe(AC_SET_FAN_TOPIC, ac_state_callback);
-  mqtt.subscribe(AC_SET_TEMPERATURE_TOPIC, ac_state_callback);
-  mqtt.subscribe(AC_SET_MODE_TOPIC, ac_state_callback);
+  mqtt.subscribe(AC_SET_FAN_TOPIC);
+  mqtt.subscribe(AC_SET_TEMPERATURE_TOPIC);
+  mqtt.subscribe(AC_SET_MODE_TOPIC);
 #endif
-  mqtt.subscribe(STATE_REQUEST_TOPIC, state_request_callback);
+  mqtt.subscribe(STATE_REQUEST_TOPIC);
+}
+
+void mqtt_callback(char *topic, byte *payload, unsigned int length)
+{
+  uint8_t topic_length = strlen(topic);
+  char topic_trim[50];
+  char payload_nt[length + 1];
+  memcpy(payload_nt, payload, length);
+  payload_nt[length] = NULL;
+  strncpy(topic_trim, topic + base_topic_length - 1, topic_length);
+  if ((!strncmp(topic_trim, "/pwm/", 5)) && !strncmp(topic_trim + 7, "/set/state", 10))
+  {
+    pwm_state_callback(topic_trim, topic_length, payload_nt, length);
+  }
+  else if ((!strncmp(topic_trim, "/pwm/", 5)) && !strncmp(topic_trim + 7, "/set/value", 10))
+  {
+    pwm_value_callback(topic_trim, topic_length, payload_nt, length);
+  } else if(!strcmp(topic,STATE_REQUEST_TOPIC)) {
+    state_request_callback();
+  }
+  else
+  {
+    ac_state_callback(topic, topic_length, payload_nt, length);
+  }
+  user_mqtt_callback(topic, topic_length, payload_nt, length);
 }
 
 void thread_initialization()
@@ -536,27 +560,27 @@ void thread_initialization()
   user_timer_tick.setInterval(15000);
 }
 
-void pwm_state_callback(String topic, String message)
+void pwm_state_callback(char *topic, uint8_t topic_length, char *payload, unsigned int payload_length)
 {
-  int a = topic.charAt(base_topic_length + 4) - '0';
-  int b = topic.charAt(base_topic_length + 5) - '0';
+  int a = topic[5] - '0';
+  int b = topic[6] - '0';
   int id = 10 * a + b;
-  if (message.compareTo("on") == 0)
+  if (!strcmp(payload, "on"))
   {
     pwm_set_state(id, true);
   }
-  else if (message.compareTo("off") == 0)
+  else if (!strcmp(payload, "off"))
   {
     pwm_set_state(id, false);
   }
 }
 
-void pwm_value_callback(String topic, String message)
+void pwm_value_callback(char *topic, uint8_t topic_length, char *payload, unsigned int payload_length)
 {
-  int a = topic.charAt(base_topic_length + 4) - '0';
-  int b = topic.charAt(base_topic_length + 5) - '0';
+  int a = topic[5] - '0';
+  int b = topic[6] - '0';
   int id = 10 * a + b;
-  int value = message.toInt();
+  int value = atoi(payload);
   pwm_set_value(id, value);
 }
 
@@ -610,13 +634,15 @@ void publish_pwm_state(int id)
   PWM_VALUE_TOPIC[base_topic_length + 5] = (id % 10) + '0';
   if (state == 1)
   {
-    mqtt_client.publish(PWM_STATE_TOPIC, "on");
+    mqtt.publish(PWM_STATE_TOPIC, "on");
   }
   else if (state == 0)
   {
-    mqtt_client.publish(PWM_STATE_TOPIC, "off");
+    mqtt.publish(PWM_STATE_TOPIC, "off");
   }
-  mqtt.publish(String(PWM_VALUE_TOPIC), String(value));
+  char temp[6];
+  itoa(value, temp, DEC);
+  mqtt.publish(PWM_VALUE_TOPIC, temp);
 }
 
 void pwm_set_state(int id, int state)
@@ -723,10 +749,10 @@ void publish_input_state(int id, int state)
 {
   INPUTS_TOPIC[base_topic_length + 6] = ((id - id % 10) / 10) + '0';
   INPUTS_TOPIC[base_topic_length + 7] = (id % 10) + '0';
-  mqtt.publish(String(INPUTS_TOPIC), state ? "1" : "0");
+  mqtt.publish(INPUTS_TOPIC, state ? "1" : "0");
 }
 
-void state_request_callback(String topic, String message)
+void state_request_callback()
 {
   publish_input_states();
   publish_pwm_states();
@@ -749,80 +775,79 @@ void ir_loop()
 #ifdef ENABLE_CLIMATE_MODULE
 void publish_ac_state()
 {
-  String temp = "";
   switch (ac_mode)
   {
   case 0:
-    temp = "off";
+    mqtt.publish(AC_MODE_TOPIC, "off");
     break;
   case 1:
-    temp = "cool";
+    mqtt.publish(AC_MODE_TOPIC, "cool");
     break;
   case 2:
-    temp = "fan_only";
+    mqtt.publish(AC_MODE_TOPIC, "fan_only");
   default:
     break;
   }
-  mqtt.publish(String(AC_MODE_TOPIC), temp);
-  mqtt.publish(String(AC_TEMPERATURE_TOPIC), String(ac_temperature));
+  char temp[5];
+  itoa(ac_temperature, temp, DEC);
+  mqtt.publish(AC_TEMPERATURE_TOPIC, temp);
   switch (ac_fan_speed)
   {
   case 0:
-    temp = "auto";
+    mqtt.publish(AC_FAN_TOPIC, "auto");
     break;
   case 1:
-    temp = "high";
+    mqtt.publish(AC_FAN_TOPIC, "high");
     break;
   case 2:
-    temp = "med";
+    mqtt.publish(AC_FAN_TOPIC, "medium");
     break;
   case 3:
-    temp = "low";
+    mqtt.publish(AC_FAN_TOPIC, "low");
     break;
   }
-  mqtt.publish(String(AC_FAN_TOPIC), temp);
 }
 
-void ac_state_callback(String topic, String message)
+void ac_state_callback(char *topic, uint8_t topic_length, char *payload, unsigned int payload_length)
 {
-  if (topic.compareTo(String(AC_SET_TEMPERATURE_TOPIC)) == 0)
+  if (!strcmp(topic, AC_SET_TEMPERATURE_TOPIC))
   {
-    int new_temp = message.toInt();
+    int new_temp = atoi(payload);
     if (new_temp >= AC_MIN_TEMPERATURE && new_temp <= AC_MAX_TEMPERATURE)
     {
       ac_set_state(ac_mode, new_temp, ac_fan_speed);
     }
   }
-  else if (topic.compareTo(String(AC_SET_MODE_TOPIC)) == 0)
+  else if (!strcmp(topic, AC_SET_MODE_TOPIC))
   {
-    if (message.compareTo("off") == 0)
+    if (!strcmp(payload, "off"))
     {
       ac_set_state(0, ac_temperature, ac_fan_speed);
     }
-    else if (message.compareTo("cool") == 0)
+    else if (!strcmp(payload, "cool"))
     {
       ac_set_state(1, ac_temperature, ac_fan_speed);
     }
-    else if (message.compareTo("fan_only") == 0)
+    else if (!strcmp(payload, "fan_only"))
     {
       ac_set_state(2, ac_temperature, ac_fan_speed);
     }
   }
-  else if (topic.compareTo(String(AC_SET_FAN_TOPIC)) == 0)
+  else if (!strcmp(topic, AC_SET_FAN_TOPIC))
   {
-    if (message.compareTo("auto") == 0)
+    if (!strcmp(payload, "auto"))
     {
       ac_set_state(ac_mode, ac_temperature, 0);
     }
-    else if (message.compareTo("low") == 0)
+    else if (!strcmp(payload, "high"))
     {
       ac_set_state(ac_mode, ac_temperature, 1);
     }
-    else if (message.compareTo("med") == 0)
+    else if (!strcmp(payload, "medium"))
     {
       ac_set_state(ac_mode, ac_temperature, 2);
     }
-    else if (message.compareTo("high") == 0)
+    else if (!strcmp(payload, "low"))
     {
       ac_set_state(ac_mode, ac_temperature, 3);
     }
@@ -859,7 +884,7 @@ void ac_set_state(int mode, int temperature, int fan_speed)
     IrSender.sendRaw(ir_code_off, sizeof(ir_code_off) / sizeof(ir_code_off[0]), NEC_KHZ);
     break;
   case 1:
-    IrSender.sendRaw(ir_code_cool[fan_speed][temperature], sizeof(ir_code_cool[fan_speed][temperature]) / sizeof(ir_code_cool[fan_speed][0]), NEC_KHZ);
+    IrSender.sendRaw(ir_code_cool[fan_speed][temperature], sizeof(ir_code_cool[fan_speed][temperature]) / sizeof(ir_code_cool[fan_speed][temperature][0]), NEC_KHZ);
     break;
   case 2:
     IrSender.sendRaw(ir_code_fan[fan_speed], sizeof(ir_code_fan[fan_speed]) / sizeof(ir_code_fan[fan_speed][0]), NEC_KHZ);
@@ -877,10 +902,12 @@ void publish_env_state()
   case DHTLIB_OK:
     current_room_humid = env_sensor.getHumidity();
     current_room_temp = env_sensor.getTemperature();
-    mqtt.publish(String(AC_ROOM_TEMPERATURE_TOPIC), String(current_room_temp));
-    mqtt_client.loop();
-    mqtt.publish(String(AC_HUMIDITY_TOPIC), String(current_room_humid));
-    mqtt_client.loop();
+    char temp[5];
+    dtostrf(current_room_temp, 0, 2, temp);
+    mqtt.publish(AC_ROOM_TEMPERATURE_TOPIC, temp);
+    dtostrf(current_room_humid, 0, 2, temp);
+    mqtt.publish(AC_HUMIDITY_TOPIC, temp);
+    mqtt.loop();
 #ifdef ENABLE_INTERNAL_LCD
     if (lcd_current_page == 4)
     {
@@ -892,10 +919,10 @@ void publish_env_state()
 #endif
     break;
   default:
-    mqtt.publish(String(AC_ROOM_TEMPERATURE_TOPIC), "ERROR");
-    mqtt_client.loop();
-    mqtt.publish(String(AC_HUMIDITY_TOPIC), "ERROR");
-    mqtt_client.loop();
+    mqtt.publish(AC_ROOM_TEMPERATURE_TOPIC, "ERROR");
+    mqtt.loop();
+    mqtt.publish(AC_HUMIDITY_TOPIC, "ERROR");
+    mqtt.loop();
   }
 }
 #endif
diff --git a/src/espmega_iot_core.hpp b/src/espmega_iot_core.hpp
index bf03bf5..42582ed 100644
--- a/src/espmega_iot_core.hpp
+++ b/src/espmega_iot_core.hpp
@@ -9,7 +9,6 @@
 #endif
 #include <ETH.h>
 #include <PubSubClient.h>
-#include <PubSubClientTools.h>
 #include <Thread.h>
 #include <StaticThreadController.h>
 #ifdef ENABLE_IR_MODULE
@@ -35,15 +34,16 @@
 #endif
 #include "espmega_iot_timer.hpp"
 
+void mqtt_callback(char* topic, byte* payload, unsigned int length);
 void virtual_interrupt_loop();
 void virtual_interrupt_callback(int pin, int state);
 void network_begin();
 void mqtt_connect();
 void mqtt_subscribe();
 void thread_initialization();
-void pwm_state_callback(String topic, String message);
-void pwm_value_callback(String topic, String message);
-void state_request_callback(String topic, String message);
+void pwm_state_callback(char* topic, uint8_t topic_length, char* payload, unsigned int payload_length);
+void pwm_value_callback(char* topic, uint8_t topic_length, char* payload, unsigned int payload_length);
+void state_request_callback();
 void io_begin();
 void ir_loop();
 
@@ -66,7 +66,7 @@ void publish_env_state();
 uint8_t ac_get_temperature();
 uint8_t ac_get_mode();
 uint8_t ac_get_fan_speed();
-void ac_state_callback(String topic, String message);
+void ac_state_callback(char* topic, uint8_t topic_length, char* payload, unsigned int payload_length);
 void ac_set_state(int mode, int temperature, int fan_speed);
 
 void publish_input_states();
diff --git a/src/user_code.cpp b/src/user_code.cpp
index 929235b..0af23b5 100644
--- a/src/user_code.cpp
+++ b/src/user_code.cpp
@@ -109,4 +109,8 @@ float adc2watts(uint16_t adc_value)
     float secondary_current = burden_voltage / BURDEN_RESISTANCE;
     float primary_current = secondary_current / RATIO;
     return primary_current * VOLTAGE;
+}
+
+void user_mqtt_callback(char* topic, uint8_t topic_length, char* payload, unsigned int payload_length) {
+
 }
\ No newline at end of file
diff --git a/src/user_code.hpp b/src/user_code.hpp
index 7f65cf6..ece4efa 100644
--- a/src/user_code.hpp
+++ b/src/user_code.hpp
@@ -44,6 +44,7 @@ void bt0PopCallback(void *ptr);
 void user_state_request_callback();
 float adc2watts(uint16_t adc_value);
 
+void user_mqtt_callback(char* topic, uint8_t topic_length, char* payload, unsigned int payload_length);
 
 // ESPMega IoT Core Build-in Functions
 extern void pwm_set_state(int id, int state);
@@ -60,5 +61,4 @@ extern uint8_t ac_get_temperature();
 extern uint8_t ac_get_mode();
 extern uint8_t ac_get_fan_speed();
 extern bool standalone;
-extern PubSubClient mqtt_client;
-extern PubSubClientTools mqtt;
\ No newline at end of file
+extern PubSubClient mqtt;
\ No newline at end of file