diff --git a/.vscode/settings.json b/.vscode/settings.json
index a06ac45..45b4a6e 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -17,6 +17,7 @@
         "debug.h": "c",
         "systick.h": "c",
         "timer.h": "c",
-        "stdint.h": "c"
+        "stdint.h": "c",
+        "mqtt_interface.h": "c"
     }
 }
\ No newline at end of file
diff --git a/include/config.h b/include/config.h
index 2d4625f..318cd51 100644
--- a/include/config.h
+++ b/include/config.h
@@ -12,7 +12,7 @@
 // MQTT configuration
 #define CLIENT_ID "ch32_node"
 
-#define MQTT_TARGET_IP {192, 168, 102, 147}
+#define MQTT_TARGET_IP {192, 168, 102, 100}
 #define MQTT_TARGET_PORT 1883
 
 #define MQTT_KEEP_ALIVE_INTERVAL 60
diff --git a/include/dhcp.h b/include/dhcp.h
new file mode 100644
index 0000000..68d0f99
--- /dev/null
+++ b/include/dhcp.h
@@ -0,0 +1,19 @@
+#ifndef DHCP_H
+#define DHCP_H
+
+#include <stdint.h>
+
+typedef enum {
+  DHCP_STATE_INIT,
+  DHCP_STATE_DISCOVER,
+  DHCP_STATE_REQUEST,
+  DHCP_STATE_LEASED,
+  DHCP_STATE_RENEW,
+  DHCP_STATE_RELEASE
+} dhcp_state_t;
+
+void dhcp_init(void);
+void dhcp_process(void);
+uint8_t dhcp_get_state(void);
+
+#endif
diff --git a/include/systick.h b/include/systick.h
index 0f4e55c..bfcfe82 100644
--- a/include/systick.h
+++ b/include/systick.h
@@ -8,9 +8,8 @@
   (uint32_t)(FUNCONF_SYSTEM_CORE_CLOCK / TIMER_DELAY)
 #define millis() (systick_millis)
 
+// ms counter incremented by SysTick
+extern volatile uint32_t systick_millis;
 void init_systick(void);
 
-// ms counter incremented by SysTick
-// extern volatile uint32_t systick_millis;
-
 #endif  // SYSTICK_H
diff --git a/include/w5500.h b/include/w5500.h
index 02a01c3..9f6d344 100644
--- a/include/w5500.h
+++ b/include/w5500.h
@@ -24,13 +24,16 @@ void handle_ip_assigned(void);
 // Initializes the W5500 chip
 void configure_network(void);
 
-void configure_dhcp(void);
+// void configure_dhcp(void);
+void dhcp_init(void);
+void dhcp_process(void);
 
 // resolves a domain name
 void resolve_domain_name(const char* domain_name);
 
 // init and connect the MQTT client
-MQTTClient setup_mqtt_client(Network* network, ch32_mqtt_options_t* opts);
+int setup_mqtt_client(Network* network, ch32_mqtt_options_t* opts,
+                      MQTTClient* client);
 
 int subscribe_to_topic(MQTTClient* client, const char* topic, enum QoS qos,
                        messageHandler message_callback);
diff --git a/lib/ioLibrary_Driver/DHCP/dhcp.c b/lib/ioLibrary_Driver/DHCP/dhcp.c
index 741cc06..1a2d9cd 100644
--- a/lib/ioLibrary_Driver/DHCP/dhcp.c
+++ b/lib/ioLibrary_Driver/DHCP/dhcp.c
@@ -974,10 +974,7 @@ void DHCP_init(uint8_t s, uint8_t * buf)
 /* Reset the DHCP timeout count and retry count. */
 void reset_DHCP_timeout(void)
 {
-#ifdef _DHCP_DEBUG_
-	printf("> reset_DHCP_timeout !!!\r\n");
-#endif
-	// dhcp_tick_1s = 0;
+	dhcp_tick_1s = 0;
 	dhcp_tick_next = DHCP_WAIT_TIME;
 	dhcp_retry_count = 0;
 }
diff --git a/src/dhcp.c b/src/dhcp.c
new file mode 100644
index 0000000..2a93fb5
--- /dev/null
+++ b/src/dhcp.c
@@ -0,0 +1,105 @@
+#include "dhcp.h"
+
+#include <DHCP/dhcp.h>
+#include <socket.h>
+
+#include "debug.h"
+#include "systick.h"
+#include "w5500.h"
+
+static volatile dhcp_state_t dhcp_state = DHCP_STATE_INIT;
+static volatile uint32_t dhcp_lease_time = 0;
+static volatile uint32_t dhcp_last_time = 0;
+static volatile uint32_t dhcp_retry_count = 0;
+static uint32_t last_check_time = 0;
+
+// Buffers
+static uint8_t dhcp_buffer[512];
+static wiz_NetInfo current_net_info = {
+    .mac = {0xEA, 0x11, 0x22, 0x33, 0x44, 0xEA}, .dhcp = NETINFO_DHCP};
+
+static void update_network_config(void) {
+  wizchip_setnetinfo(&current_net_info);
+  DEBUG_PRINT("IP config: %d.%d.%d.%d\n", current_net_info.ip[0],
+              current_net_info.ip[1], current_net_info.ip[2],
+              current_net_info.ip[3]);
+}
+
+void callback_ip_assigned(void) {
+  dhcp_lease_time = getDHCPLeasetime();
+  DEBUG_PRINT("IP newly assigned! Lease time: %lu sec\n", dhcp_lease_time);
+
+  getIPfromDHCP(current_net_info.ip);
+  getGWfromDHCP(current_net_info.gw);
+  getSNfromDHCP(current_net_info.sn);
+  getDNSfromDHCP(current_net_info.dns);
+
+  dhcp_state = DHCP_STATE_LEASED;
+}
+
+void callback_ip_updated(void) {
+  dhcp_lease_time = getDHCPLeasetime();
+  DEBUG_PRINT("IP lease updated! New lease time: %lu sec\n", dhcp_lease_time);
+
+  getIPfromDHCP(current_net_info.ip);
+  getGWfromDHCP(current_net_info.gw);
+  getSNfromDHCP(current_net_info.sn);
+  getDNSfromDHCP(current_net_info.dns);
+
+  dhcp_state = DHCP_STATE_LEASED;
+}
+
+void callback_ip_conflict(void) {
+  DEBUG_PRINT("IP conflict!\n");
+  dhcp_state = DHCP_STATE_INIT;
+  dhcp_retry_count = 0;
+}
+
+void dhcp_init(void) {
+  setSHAR(current_net_info.mac);
+  DHCP_init(DHCP_SOCKET, dhcp_buffer);
+  reg_dhcp_cbfunc(callback_ip_assigned, callback_ip_updated,
+                  callback_ip_conflict);
+  dhcp_state = DHCP_STATE_INIT;
+  dhcp_retry_count = 0;
+}
+
+void dhcp_process(void) {
+  uint32_t current_time = millis();
+
+  // 500ms processing
+  if ((current_time - last_check_time) >= 500) {
+    last_check_time = current_time;
+
+    switch (dhcp_state) {
+      case DHCP_STATE_INIT:
+        DHCP_run();
+        if (dhcp_state == DHCP_STATE_LEASED) {
+          update_network_config();
+        }
+        break;
+
+      case DHCP_STATE_LEASED:
+        // renew @ 50% of lease time
+        if (current_time - dhcp_last_time >= (dhcp_lease_time * 500)) {
+          dhcp_state = DHCP_STATE_RENEW;
+          DHCP_run();
+        }
+        break;
+
+      case DHCP_STATE_RENEW:
+        DHCP_run();
+        if (dhcp_state == DHCP_STATE_LEASED) {
+          update_network_config();
+          dhcp_last_time = current_time;
+        }
+        break;
+
+      default:
+        DHCP_run();
+        break;
+    }
+  }
+}
+
+uint8_t dhcp_get_state(void) { return dhcp_state; }
\ No newline at end of file
diff --git a/src/main.c b/src/main.c
index 1a15447..aed7c6c 100644
--- a/src/main.c
+++ b/src/main.c
@@ -2,6 +2,7 @@
 
 #include "ch32v003fun.h"
 #include "debug.h"
+#include "dhcp.h"
 #include "gpio.h"
 #include "socket.h"
 #include "spi_dma.h"
@@ -10,20 +11,35 @@
 #include "uart.h"
 #include "w5500.h"
 
-void init_system(void) {
-  SystemInit();
+#define MQTT_RECONNECT_INTERVAL 5000
+#define MQTT_YIELD_INTERVAL 100
+#define W5500_INIT_DELAY_MS 55
+#define DHCP_TIMEOUT_MS 15000
 
-  init_gpio();
-  init_systick();
-  tim2_init();
+typedef struct {
+  Network network;
+  MQTTClient client;
+  ch32_mqtt_options_t opts;
+  uint32_t last_reconnect;
+  uint32_t last_yield;
+  uint8_t is_connected;
+} mqtt_state_t;
 
-  init_uart(UART_BRR_APB1);
-  init_spidma();
+// init MQTT state
+void mqtt_init(mqtt_state_t* state, char* client_id) {
+  // TODO
+  state->opts.clientid = client_id;
+  state->opts.username = "";
+  state->opts.password = "";
+  state->opts.qos = QOS0;
+  state->last_reconnect = 0;
+  state->last_yield = 0;
+  state->is_connected = 0;
 }
 
 // cb fn for when a message is received
 void message_arrived(MessageData* md) {
-  if (md == NULL || md->message == NULL) {
+  if (!md || !md->message) {
     DEBUG_PRINT("Error: MessageData is NULL.\n");
     return;
   }
@@ -47,57 +63,90 @@ void message_arrived(MessageData* md) {
   }
 }
 
-// void print_bin(uint32_t value) {
-//   for (int i = 31; i >= 0; i--) {
-//     DEBUG_PRINT("%d", (value >> i) & 1);
-//     if (i % 4 == 0) printf(" ");
-//   }
-//   DEBUG_PRINT("\n");
-// }
+// mqtt reconnect
+// TODO: setup will, publish discovery messages, setup subs
+void mqtt_process(mqtt_state_t* state) {
+  uint32_t now = millis();
+  int rc;
+
+  if (!state->is_connected) {
+    if (now - state->last_reconnect >= MQTT_RECONNECT_INTERVAL) {
+      DEBUG_PRINT("Attempting MQTT connection...\n");
+
+      rc = setup_mqtt_client(&state->network, &state->opts, &state->client);
+      if (rc == 0) {
+        DEBUG_PRINT("MQTT connected\n");
+        state->is_connected = 1;
+
+        rc = subscribe_to_topic(&state->client, SUB_TOPIC, QOS0,
+                                message_arrived);
+        if (rc != 0) {
+          DEBUG_PRINT("Subscribe failed: %d\n", rc);
+          state->is_connected = 0;
+        } else {
+          publish_message(&state->client, "Device connected", PUB_TOPIC);
+        }
+      }
+      state->last_reconnect = now;
+    }
+  } else if (now - state->last_yield >= MQTT_YIELD_INTERVAL) {
+    rc = MQTTYield(&state->client, 100);
+    if (rc != 0) {
+      DEBUG_PRINT("Yield failed: %d\n", rc);
+      state->is_connected = 0;
+    }
+    state->last_yield = now;
+  }
+}
+
+void init_system(void) {
+  SystemInit();
+
+  init_gpio();
+  init_systick();
+  tim2_init();
+
+  init_uart(UART_BRR_APB1);
+  init_spidma();
+}
+
+// Wait for DHCP lease
+static int wait_for_dhcp(void) {
+  uint32_t start = millis();
+  while (dhcp_get_state() != DHCP_STATE_LEASED) {
+    if (millis() - start >= DHCP_TIMEOUT_MS) {
+      DEBUG_PRINT("DHCP timeout\n");
+      return 0;
+    }
+    dhcp_process();
+  }
+  return 1;
+}
 
 int main(void) {
   init_system();
-  Delay_Ms(55);
+  Delay_Ms(W5500_INIT_DELAY_MS);
 
-  // uint32_t intsyscr = __get_INTSYSCR();
-  // DEBUG_PRINT("INTSYSCR:\n");
-  // DEBUG_PRINT("hex: 0x%08X\n", intsyscr);
-  // DEBUG_PRINT("bin: ");
-  // print_binary(intsyscr);
-
-  // DEBUG_PRINT("init_system() done\n");
+  // Configure network and DHCP
   configure_network();
+  dhcp_init();
 
-  // TODO: enabling any kind of SysTick IRQ literally causes the socket to hang
-  // forever with 1ms interval the hang is on DHCP_ACK, on check_DHCP_leasedIP
-  // -> sendto() ARP req with 100ms it happens somewhere on DNS req
-
-  // systick irq enable here would complete the DHCP configuration and hang on
-  // DNS.. init_systick();
-
-  configure_dhcp();
-  resolve_domain_name("example.com");
-
-  Network network;
-  ch32_mqtt_options_t opts = {CLIENT_ID, "", "", QOS0};
-
-  // Set up MQTT client
-  MQTTClient client = setup_mqtt_client(&network, &opts);
-  subscribe_to_topic(&client, SUB_TOPIC, QOS0, message_arrived);
-
-  // Publish a message
-  publish_message(&client, "hi", PUB_TOPIC);
-
-  while (1) {
-    // if ((millis() - dhcp_last_invocation) >= DHCP_INTERVAL) {
-    //   dhcp_last_invocation = millis();
-    //   DHCP_run();
-    // }
-    MQTTYield(&client, 1000);  // keepalive
+  if (!wait_for_dhcp()) {
+    while (1) {
+      // todo: handle err
+    }
   }
 
-  MQTTDisconnect(&client);
-  close(TCP_SOCKET);
+  resolve_domain_name("example.com");
+
+  // mqtt
+  mqtt_state_t mqtt;
+  mqtt_init(&mqtt, CLIENT_ID);
+
+  while (1) {
+    dhcp_process();
+    mqtt_process(&mqtt);
+  }
 
   return 0;
-}
+}
\ No newline at end of file
diff --git a/src/systick.c b/src/systick.c
index ef5ca07..cd21ade 100644
--- a/src/systick.c
+++ b/src/systick.c
@@ -1,11 +1,11 @@
 #include "systick.h"
 
+#include "MQTT/mqtt_interface.h"
 #include "ch32v003fun.h"
 #include "debug.h"
 
 // ms counter
 volatile uint32_t systick_millis = 0;
-// volatile int toggle_state = 0;
 
 void init_systick(void) {
   SysTick->CTLR = 0;
@@ -42,4 +42,5 @@ void SysTick_Handler(void) {
   // clear irq
   SysTick->SR = 0;
   systick_millis++;
-}
\ No newline at end of file
+  MilliTimer_Handler();
+}
diff --git a/src/w5500.c b/src/w5500.c
index 4b0b727..ea7b501 100644
--- a/src/w5500.c
+++ b/src/w5500.c
@@ -11,46 +11,10 @@
 #include "config.h"
 #include "debug.h"
 #include "spi_dma.h"
+#include "systick.h"
 
-volatile uint32_t count = 0;
-volatile int ip_assigned = 0;
-
-// Global buffers for DHCP and DNS
-static uint8_t dhcp_buffer[512];
 static uint8_t dns_buffer[512];
 
-// Function to handle IP assignment details
-void handle_ip_assigned(void) {
-  DEBUG_PRINT("IP Assigned!\n");
-
-  wiz_NetInfo net_info;
-  getIPfromDHCP(net_info.ip);
-  getGWfromDHCP(net_info.gw);
-  getSNfromDHCP(net_info.sn);
-
-  uint8_t dns[4];
-  getDNSfromDHCP(dns);
-
-  DEBUG_PRINT(
-      "IP:  %d.%d.%d.%d\nGW:  %d.%d.%d.%d\nNet: %d.%d.%d.%d\nDNS: "
-      "%d.%d.%d.%d\n",
-      net_info.ip[0], net_info.ip[1], net_info.ip[2], net_info.ip[3],
-      net_info.gw[0], net_info.gw[1], net_info.gw[2], net_info.gw[3],
-      net_info.sn[0], net_info.sn[1], net_info.sn[2], net_info.sn[3], dns[0],
-      dns[1], dns[2], dns[3]);
-
-  wizchip_setnetinfo(&net_info);
-}
-
-// Callback functions
-void callback_ip_assigned(void) {
-  DEBUG_PRINT("Callback: IP assigned! Leased time: %lu sec\n",
-              getDHCPLeasetime());
-  ip_assigned = 1;
-}
-
-void callback_ip_conflict(void) { DEBUG_PRINT("Callback: IP conflict!\n"); }
-
 void configure_network(void) {
   DEBUG_PRINT("===\n");
   DEBUG_PRINT("Starting network configuration...\n");
@@ -65,36 +29,7 @@ void configure_network(void) {
   wizchip_init(rx_tx_buff_sizes, rx_tx_buff_sizes);
 }
 
-void configure_dhcp(void) {
-  wiz_NetInfo net_info = {.mac = {0xEA, 0x11, 0x22, 0x33, 0x44, 0xEA},
-                          .dhcp = NETINFO_DHCP};
-  setSHAR(net_info.mac);
-  DHCP_init(DHCP_SOCKET, dhcp_buffer);
-
-  // Register DHCP callbacks
-  reg_dhcp_cbfunc(callback_ip_assigned, callback_ip_assigned,
-                  callback_ip_conflict);
-
-  // Attempt to acquire an IP address using DHCP
-  // retry
-  uint8_t retries = 0;
-
-  while (!ip_assigned && retries < 30) {
-    DHCP_run();
-    // Delay_Ms(100);
-    DEBUG_PRINT("DHCP_run()...\n");
-    retries++;
-  }
-
-  if (!ip_assigned) {
-    DEBUG_PRINT("\r\nIP was not assigned\r\n");
-    return;
-  }
-
-  handle_ip_assigned();
-}
-
-// todo: rm
+// todo: rm !!!
 void resolve_domain_name(const char* domain_name) {
   DEBUG_PRINT("Resolving domain name \"%s\"...\n", domain_name);
 
@@ -119,21 +54,23 @@ void resolve_domain_name(const char* domain_name) {
   }
 }
 
-MQTTClient setup_mqtt_client(Network* network, ch32_mqtt_options_t* opts) {
+int setup_mqtt_client(Network* network, ch32_mqtt_options_t* opts,
+                      MQTTClient* client) {
   static unsigned char tx_buffer[MQTT_TX_BUFFER_SIZE];
   static unsigned char rx_buffer[MQTT_RX_BUFFER_SIZE];
-  MQTTClient client;
   int rc;
   uint8_t target_ip[] = MQTT_TARGET_IP;
 
+  // Initialize network
   NewNetwork(network, TCP_SOCKET);
-  if (ConnectNetwork(network, target_ip, MQTT_TARGET_PORT) != SOCK_OK) {
-    DEBUG_PRINT("Network connection failed.\n");
-    return (MQTTClient){0};  // Return an empty client on failure
+  rc = ConnectNetwork(network, target_ip, MQTT_TARGET_PORT);
+  if (rc != SOCK_OK) {
+    DEBUG_PRINT("Network connection failed: %d\n", rc);
+    return -1;
   }
 
   // Initialize the MQTT client
-  MQTTClientInit(&client, network, MQTT_COMMAND_TIMEOUT_MS, tx_buffer,
+  MQTTClientInit(client, network, MQTT_COMMAND_TIMEOUT_MS, tx_buffer,
                  sizeof(tx_buffer), rx_buffer, sizeof(rx_buffer));
 
   // Setup MQTT connection data
@@ -147,13 +84,13 @@ MQTTClient setup_mqtt_client(Network* network, ch32_mqtt_options_t* opts) {
   connect_data.cleansession = 1;
 
   // Connect to MQTT broker
-  rc = MQTTConnect(&client, &connect_data);
+  rc = MQTTConnect(client, &connect_data);
   if (rc != 0) {
     DEBUG_PRINT("Failed to connect: %d\n", rc);
-    return (MQTTClient){0};  // Return an empty client on failure
+    return -2;
   }
 
-  return client;
+  return 0;
 }
 
 int subscribe_to_topic(MQTTClient* client, const char* topic, enum QoS qos,
@@ -163,7 +100,7 @@ int subscribe_to_topic(MQTTClient* client, const char* topic, enum QoS qos,
     DEBUG_PRINT("Failed to subscribe to %s: %d\n", topic, rc);
     return rc;
   }
-  return 0;  // Success
+  return 0;
 }
 
 void publish_message(MQTTClient* client, const char* payload,