Notes

#include <SoftwareSerial.h>
#include <SerialESP8266wifi.h>

/* TCP server/client example, that manages client connections, checks for messages
* when client is connected and parses commands. Connect to the ESP8266 IP using
* a TCP client such as telnet, eg: telnet 192.168.0.X 2121
*
* ESP8266 should be AT firmware based on 1.5 SDK or later
*
* 2016 - J.Whittington - engineer.john-whittington.co.uk
*/

#define sw_serial_rx_pin 4 // Connect this pin to TX on the esp8266
#define sw_serial_tx_pin 6 // Connect this pin to RX on the esp8266
#define esp8266_reset_pin 5 // Connect this pin to CH_PD on the esp8266, not reset. (let reset be unconnected)

#define SERVER_PORT "2121"
#define SSID "YourSSID"
#define PASSWORD "YourPassword"

SoftwareSerial swSerial(sw_serial_rx_pin, sw_serial_tx_pin);

// the last parameter sets the local echo option for the ESP8266 module..
SerialESP8266wifi wifi(Serial, Serial, esp8266_reset_pin, swSerial);

void processCommand(WifiMessage msg);

uint8_t wifi_started = false;

// TCP Commands
const char RST[] PROGMEM = "RST";
const char IDN[] PROGMEM = "*IDN?";

void setup() {

// start debug serial
swSerial.begin(9600);
// start HW serial for ESP8266 (change baud depending on firmware)
Serial.begin(115200);
while (!Serial)
;
Serial.println("Starting wifi");

swSerial.println("Starting wifi");
wifi.setTransportToTCP();// this is also default
wifi.endSendWithNewline(false); // Will end all transmissions with a newline and carrage return ie println.. default is true

wifi_started = wifi.begin();
if (wifi_started) {
wifi.connectToAP(SSID, PASSWORD);
wifi.startLocalServer(SERVER_PORT);
} else {
// ESP8266 isn't working..
}
}

void loop() {

static WifiConnection *connections;

// check connections if the ESP8266 is there
if (wifi_started)
wifi.checkConnections(&connections);

// check for messages if there is a connection
for (int i = 0; i < MAX_CONNECTIONS; i++) {
if (connections[i].connected) {
// See if there is a message
WifiMessage msg = wifi.getIncomingMessage();
// Check message is there
if (msg.hasData) {
// process the command
processCommand(msg);
}
}
}
}

void processCommand(WifiMessage msg) {
// return buffer
char espBuf[MSG_BUFFER_MAX];
// scanf holders
int set;
char str[16];

// Get command and setting
sscanf(msg.message,"%15s %d",str,&set);
/* swSerial.print(str);*/
/* swSerial.println(set);*/

if ( !strcmp_P(str,IDN) ) {
wifi.send(msg.channel,"ESP8266wifi Example");
}
// Reset system by temp enable watchdog
else if ( !strcmp_P(str,RST) ) {
wifi.send(msg.channel,"SYSTEM RESET...");
// soft reset by reseting PC
asm volatile (" jmp 0");
}
// Unknown command
else {
wifi.send(msg.channel,"ERR");
}
}