ESP8266-Based Serial WiFi Shield for Arduino Use Guide


ESP8266-Based Serial WiFi Shield for Arduino Use Guide


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UART WIFI Shield is a low power consuming wifi extension working for Arduino Uno and Mega2560

ESP8266-Based Serial WiFi Shield for Arduino is designed based on esp8266 by Espress if Systems, pin-compatible with Arduino UNO/Mega2560 DevBorad.

The serial wifi shield has the following features:

1.WiFi module is industrial-grade chips ESP8266, which is ESP-12E with metal shield, strong anti-interference ability;

2. Shield is pin-compatible with Arduino Uno, Mega2560 and other control board. A voltage converter chip is used to deal with 3.3V (Esp8266) and 5V (Arduino);

3. Dual DIP switches is used for serial ports so that this module shield can be used alone as an Arduino Uno expansion board, and also be used as ESP8266 expansion board;

4. Serial data is transported to WiFi device transparently, and vice versa. Arduino program does not need any configuration;

5. WebServer is developed to configure WiFi parameters and serial port parameters;

6. The module shield can be used as an independent ESP8266 development board. for instance, downloading the official AT commands firmware, NodeMCU open source firmware can be used;

7. The module shield also can be used as stand-alone expansion board for Arduino Uno.


  • Wifi protocol 802.11 b/g/n ;
  • STA/AP work mode;
  • integrated TCP/IP stack, support one socket;
  • work as TCP/UDP Serve or Client mode;
  • serial portbaud rate: 1200/2400/4800/9600/19200/38400/57600/74800/ 115200 bps;
  • serial port width:5/6/7/8 bits;;
  • Extended Arduino Pin D2/3/4/5/6/7/8/9/10/11/12/13;
  • Extended ESP8266 GPIO Pin 0/2/4/5/9/10/12/13/14/15/16/ADC/EN/UART TX/UART RX;
  • RESET;
  • KEY reset;
  • WiFi current:working:≈70mA(200mA MAX),sleep:<200uA;
  • wifi speed:110-460800bps;
  • working temp:-40℃~+125℃
  • weight:20g

Interface Definition

This serial WiFi module board provides interface as shown in PCB view. And each pin functions are silk-printed in circuit board, as follows:


LED instructions:

ESP8266 wifi module has two LEDs. Red LED is for power. Blue LED indicates different function meaning as following:


Quick start:

Example A: Enter configuration mode

The wifi module factory default is in configuration mode. You should complete configuration and then start transmission mode. If you are working in transmission mode, you can push and hold KEY button for more than 1 second and back to configuration mode. Please take following steps to config the module

1) Turn on the power of the module and use another laptop or smart phone to connect wifi ssid “DoitWiFi_Config”。wifi password is:“12345678”(you can even use empty password to connect this ssid)


2) Open your laptop brower and access, you will see following page:



3) Do configuration as per above picture and click submit.

4) After submitting, the module will reboot and then enter into AP mode. Please set serial port parameters as 9600,n,8,1。

WiFi working mode hotspot(AP),ssid is “DoitWiFi_Config”,password: “12345678”. TCP Server listening port 9000. these configuration is Factory Default setting.

Arduino data send to WiFi through serial port :

Step 1) connect Arduino UNO to wifi module as per following picture


Step 2) set the two switch positions to OFF, this will disconnect wifi module from Arduino serial port.

Step 3) Load following code into Arduino IDE

void setup()

void loop()
Serial.println(“hello ESP8266 WiFi”);


Step 4) Set Wifi modue two switches to ON position which will connect wifi module to Arduino serial port.

Step 5) Use your laptop to search wifi hotspot ssid:“DoitWiFi_Config”,password “12345678”。

Step 6) run tcp udp testing/debug software in laptop.

We suggest you use tcp udp debugger which can be downloaded from:KOOKYE tcp udp debugger

Run tcp udp debugger ,create a tcp client mode connection,DestIP :,Port:9000。LocalPort:Auto。

click Connect,you will see Arduino send data “hello ESP8266 WiFi” very second

Example B: Connect remote server:

we will use WAN TCP tool to test communication between wifi module and remote server.。

Step 1) In your laptop, type ,get a temperate IP and port from DOIT TCP server. In this example, suppose we get IP port number 6551


Step 2)Push and hold KEY button in wifi mode and enter into configuration mode.

Step 3) Use your laptop to search wifi hotspot ssid:“DoitWiFi_Config”,password “12345678”

Step 4)in laptop browser, enter

check Yes box beside Enable option.

Click refresh button, it will automatically add all local wifi in to AP list.
set AP Name and AP List to the SSID of your router (Our router ssid is vership, so we set ‘vership’ here), set AP password same as your wifi password


Step 5) config wifi network parameters

Socket Type:Client

Transport Type:TCP

Remote IP: (this IP is from step 1)

Remote Port:6551 (this port number is from step 1)


5, click “Submit”


6)Run tcp udp debugger ,create a tcp client mode connection,DestIP : (from step 1),Port:6551 (from step 1)。LocalPort:Auto。


7, click Create, you will see Arduino serial data is sent to remote server every one second.


Switch between different work mode:

ESP8266 work mode relation graph:


ESP8266 wifi module serial port parameter setting options:

WiFi working mode setting

ESP8266 module wifi module can config into AP or STA working mode

If you configure the module through web page, the default mode is AP


in station section, if you check the Yes box beside Enable, the mode will change to STA. Refresh button and “AP List” drop down menu will be enabled. Click refresh , all available wifi hotspot ssid will be added into AP list


Network configuration

Wifi module can be configured in Server mode or client mode. WiFi module only support one Socket

When working in “Server” mode,“Remote IP” is disabled。“Local Port” fieldshould have a listening port number.

When working in client mode,“Remote IP” input field will become enabled

Transport type can be set to TCP or UDP。

Factory default reset

You can click “FactoryDefault” to restore factory default setting as following:

default SSID: DoitWifi_Ser2Net
default wifi password: 12345678
default web config url:
default client mode: TCP server.
default listening port : 9000
default serial port parameter: 9600,n,8,1

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