01-ESP8266-TCP Communication

• TCP communication
• MQTT communication
• Connecting to a microcontroller
• Mobile APP development - communicating with STM32 - MQTT

Basic Info

The ESP8266 itself:

Wiring is as follows:

Connecting to WiFi

Command	Response	Purpose
AT+UART=115200,8,1,0,0	OK	Set the baud rate
AT	OK	Test whether AT commands are available
AT+RST	OK, then init info	Restart the ESP8266
AT+GMR	Version info	Check the firmware version
AT+CWMODE=1	OK	Set the WiFi mode (STA mode) The ESP8266 can act as a client (STA), a hotspot (AP), or both at once (AP+STA). 0 turns WiFi off, 1 is STA mode, 2 is AP mode, 3 is AP+STA mode
AT+CWJAP="name","password"	WIFI CONNECTED WIFI GOT IP OK	Connect to WiFi
AT+CWJAP?	+CWJAP:"your WiFi name","xx:xx:xx:xx:xx:xx",channel,signal_strength	Check the connection status (verify the connection succeeded)
AT+CIFSR	+CIFSR:STAIP,"192.168.1.100" +CIFSR:STAMAC,"a4:e5:7c:26:1a:3f" OK	Get the assigned IP
AT+CWQAP	OK	Disconnect from WiFi

1. Set the WiFi mode (AT+CWMODE=1)
2. Connect to WiFi with the name and password (AT+CWJAP="name","password")

TCP Communication

As a Client

Get the local IP:
Open CMD and type ipconfig
Find the IP under Wireless LAN adapter WLAN: — that is your local IP

Command	Return value	Purpose
AT+CIPSTART="TCP","192.168.1.200",8080	CONNECT OK	Connect to the server as a TCP client
AT+CIPSEND=5	The ESP8266 returns >, at which point you enter 5 bytes of data in the serial assistant and send it; the ESP8266 will then receive the data	Send data to the server
AT+CIPCLOSE	OK	Close the TCP connection

1. Connect to the server
2. Send a message
3. Close the connection

As a Server

Command	Return value	Purpose
AT+CIPMUX=1	OK	Enable multi-connection; 0 is single connection, 1 is multi-connection
AT+CIPSERVER=1,8080	OK	Start the TCP server
AT+CIPSEND=0,5	The ESP8266 returns >, sends 5 bytes of data for another port to receive	Send data to the client
AT+CIPSERVER=0	OK	Shut down the server; it won't disconnect other already-connected devices, but it will block new devices from connecting