diff --git a/lib/radio_esp8266.c b/lib/radio_esp8266.c
index fec5f0a..bd66c23 100644
--- a/lib/radio_esp8266.c
+++ b/lib/radio_esp8266.c
@@ -23,6 +23,7 @@
 #include <stdint.h> // standard integer types
 #include <stdlib.h> // general utilities
 #include <string.h> // string and memory utilities
+#include <stdio.h> // string utilities
 
 /* STM32 (including CM3) libraries */
 #include <libopencm3/stm32/rcc.h> // real-time control clock library
@@ -49,6 +50,25 @@ static volatile uint16_t tx_used = 0; /**< number of bytes used in transmit buff
 volatile bool radio_esp8266_activity = false;
 volatile bool radio_esp8266_success = false;
 
+/** transmit data to radio
+ *  @param[in] data data to transmit
+ *  @param[in] length length of data to transmit
+ */
+static void radio_esp8266_transmit(uint8_t* data, uint8_t length) {
+	while (tx_used || !usart_get_flag(USART(RADIO_ESP8266_USART), USART_SR_TXE)) { // wait until ongoing transmission completed
+		usart_enable_tx_interrupt(USART(RADIO_ESP8266_USART)); // enable transmit interrupt
+		__WFI(); // sleep until something happened
+	}
+	usart_disable_tx_interrupt(USART(RADIO_ESP8266_USART)); // ensure transmit interrupt is disable to prevent index corruption (the ISR should already have done it)
+	radio_esp8266_activity = false; // reset status because of new activity
+	for (tx_used=0; tx_used<length && tx_used<LENGTH(tx_buffer); tx_used++) { // copy data
+		tx_buffer[tx_used] = data[length-1-tx_used]; // put character in buffer (in reverse order)
+	}
+	if (tx_used) {
+		usart_enable_tx_interrupt(USART(RADIO_ESP8266_USART)); // enable interrupt to send bytes
+	}
+}
+
 void radio_esp8266_setup(void)
 {
 	/* enable USART I/O peripheral */
@@ -77,38 +97,53 @@ void radio_esp8266_setup(void)
 	radio_esp8266_activity = false;
 	radio_esp8266_success = false;
 
-	radio_esp8266_send((uint8_t*)"AT\r\n",4); // verify if module is present
+	radio_esp8266_transmit((uint8_t*)"AT\r\n",4); // verify if module is present
 	while (!radio_esp8266_activity || !radio_esp8266_success) { // wait for response
 		__WFI(); // sleep until something happened
 	}
-	radio_esp8266_send((uint8_t*)"AT+RST\r\n",8); // reset module
+	radio_esp8266_transmit((uint8_t*)"AT+RST\r\n",8); // reset module
 	while (!radio_esp8266_activity || !radio_esp8266_success) { // wait for response
 		__WFI(); // sleep until something happened
 	}
-	radio_esp8266_send((uint8_t*)"ATE0\r\n",6); // disable echoing
-	while (!radio_esp8266_activity || !radio_esp8266_success) { // wait for response
-		__WFI(); // sleep until something happened
-	}
-	while(rx_used<13 || !memmem((char*)rx_buffer, rx_used, "WIFI GOT IP\r\n", 13)) { // wait to have IP
+	while(rx_used<13 || memcmp((char*)&rx_buffer[rx_used-13], "WIFI GOT IP\r\n", 13)!=0) { // wait to have IP
 		 __WFI(); // sleep until something happened
 	}
+	radio_esp8266_transmit((uint8_t*)"ATE0\r\n",6); // disable echoing
+	while (!radio_esp8266_activity || !radio_esp8266_success) { // wait for response
+		__WFI(); // sleep until something happened
+	}
 }
 
-void radio_esp8266_send(uint8_t* data, uint8_t length) {
-	while (tx_used || !usart_get_flag(USART(RADIO_ESP8266_USART), USART_SR_TXE)) { // wait until ongoing transmission completed
-		usart_enable_tx_interrupt(USART(RADIO_ESP8266_USART)); // enable transmit interrupt
-		__WFI(); // sleep until something happened
+void radio_esp8266_tcp_open(char* host, uint16_t port)
+{
+	char command[256] = {0}; // string to create command
+	int length = snprintf(command, LENGTH(command), "AT+CIPSTART=\"TCP\",\"%s\",%u\r\n", host, port); // create AT command to establish a TCP connection
+	if (length>0) {
+		radio_esp8266_transmit((uint8_t*)command, length);
 	}
-	usart_disable_tx_interrupt(USART(RADIO_ESP8266_USART)); // ensure transmit interrupt is disable to prevent index corruption (the ISR should already have done it)
-	radio_esp8266_activity = false; // reset status because of new activity
-	for (tx_used=0; tx_used<length && tx_used<LENGTH(tx_buffer); tx_used++) { // copy data
-		tx_buffer[tx_used] = data[length-1-tx_used]; // put character in buffer (in reverse order)
-	}
-	if (tx_used) {
-		usart_enable_tx_interrupt(USART(RADIO_ESP8266_USART)); // enable interrupt to send bytes
+}
+
+void radio_esp8266_send(uint8_t* data, uint8_t length)
+{
+	char command[16+1] = {0}; // string to create command
+	int command_length = snprintf(command, LENGTH(command), "AT+CIPSEND=%u\r\n", length); // create AT command to send data
+	if (command_length>0) {
+		radio_esp8266_transmit((uint8_t*)command, command_length); // transmit AT command
+		while (!radio_esp8266_activity || !radio_esp8266_success) { // wait for response
+			__WFI(); // sleep until something happened
+		}
+		if (!radio_esp8266_success) { // send AT command did not succeed
+			return; // don't transmit data
+		}
+		radio_esp8266_transmit(data, length); // transmit data
 	}
 }
 
+void radio_esp8266_close(void)
+{
+	radio_esp8266_transmit((uint8_t*)"AT+CIPCLOSE\r\n", 13); // send AT command to close established connection
+}
+
 /** USART interrupt service routine called when data has been transmitted or received */
 void USART_ISR(RADIO_ESP8266_USART)(void)
 {
@@ -126,13 +161,12 @@ void USART_ISR(RADIO_ESP8266_USART)(void)
 			rx_used--; // update used buffer information
 		}
 		rx_buffer[rx_used++] = usart_recv(USART(RADIO_ESP8266_USART)); // put character in buffer
-		// if the used send a packet with these strings during the commands I'm fucked (AT commands are hard to handle perfectly)
-		// ideally memmem would not be done in ISR (takes quite long)
-		if (rx_used>=4 && memmem((char*)rx_buffer, rx_used, "OK\r\n", 4)) { // OK received
+		// if the used send a packet with these strings during the commands detection the AT command response will break (AT commands are hard to handle perfectly)
+		if (rx_used>=4 && memcmp((char*)&rx_buffer[rx_used-4], "OK\r\n", 4)==0) { // OK received
 			radio_esp8266_activity = true; // response received
 			radio_esp8266_success = true; // command succeeded
 			rx_used = 0; // reset buffer
-		} else if (rx_used>=7 && memmem((char*)rx_buffer, rx_used, "ERROR\r\n", 7)) { // ERROR received
+		} else if (rx_used>=7 && memcmp((char*)&rx_buffer[rx_used-7], "ERROR\r\n", 7)==0) { // ERROR received
 			radio_esp8266_activity = true; // response received
 			radio_esp8266_success = false; // command failed
 			rx_used = 0; // reset buffer
diff --git a/lib/radio_esp8266.h b/lib/radio_esp8266.h
index 7842632..193db70 100644
--- a/lib/radio_esp8266.h
+++ b/lib/radio_esp8266.h
@@ -34,7 +34,7 @@ void radio_esp8266_setup(void);
  *  @param[in] port TCP port to connect to
  *  @note wait for activity to get success status
  */
-void radio_esp8266_tcp_open(char* host, uint32_t port);
+void radio_esp8266_tcp_open(char* host, uint16_t port);
 /** send data (requires established connection)
  *  @param[in] data data to send
  *  @param[in] length size of data to send