# KS0339 Keyestudio 8266 WIFI Module 2PCS

Download  Resources  : [Resources](./Resources.7z)

![](media/image-20260114154301498.png)

## 1. Product Overview

**1.Overview**

The package includes 2pcs of ESP8266 WIFI module.

It is an ultra-low-power UART-WiFi pass-through module with industry-leading package size and ultra-low power technology.

It is specially designed for mobile devices and IoT applications. It can connect users' physical devices to Wi-Fi wireless network for Internet or LAN communication, achieving the networking function.

**2.Features**

- Support wireless 802.11 b/g/n standard
- Support three working modes: STA/AP/STA+AP
- Built-in TCP/IP protocol stack to support multiple TCP Client connections
- Support various Socket AT commands
- Support UART/GPIO data communication interface
- Support Smart Link intelligent networking function
- Support remote firmware upgrade (OTA)
- Built-in 32-bit MCU, able to double as an application processor
- Ultra low consumption, suitable for battery powered applications.
- 3.3V single power supply

**3.Basic Parameters**

![](media/1.png)

![](media/3.png)

**4.Hardware Introduction**

ESP8266 hardware has plentiful interfaces, and can support UART，IIC，PWM，GPIO，ADC and more, suited for mobile devices and IoT applications.

- **Module pins diagram:**

![](media/image-20260114154803678.png)

- **Pins definition:**

![](media/5.png)

**5.Power Consumption**

The following measured power consumption data is based on a 3.3V power supply at 25°ambient temperature.

- 1. All measurements are done at the antenna interface.
- 2. All transmit data is based on a 90% duty cycle and measured in continuous transmission mode.

![](media/6.png)

**6.Radio Frequency Indicator**

The following data are measured at indoor temperature when the voltage is 3.3v.

![](media/7.png)

**Note:** 

1. 72.2Mbps is measured in 802.11n mode，MCS=7，GI=200uS.
2. The output power of up to +19.5dBm can be reached in 802.11b mode.

## 2. Function Description

**1.Main Function**

ESP8266 can realize the main functions as follows:

- **Serial port passthrough:** data transmission, good reliability of transfer; the maximum transmission rate is up to 460800bps.
- **PWM regulation and control:** light adjustment, RGB LED adjustment, motor speed control and more.
- **GPIO control:** control the switches, relays and more.

**2.Working Mode**

ESP8266 module supports three working modes: STA/AP/STA+AP

- **STA mode:** The ESP8266 module can access to the Internet through a router, so the mobile phone or computer can remotely control the device through the Internet.

- **AP mode:** The ESP8266 module acts as a hotspot to enable communication directly with the mobile phone or computer to achieve wireless control of the local area network (LAN).

- **STA+AP mode:** The coexistence mode of the above two modes, that is, can achieve the seamless switching through the Internet control, more convenient for operation.

**2.Applications**

- Serial port CH340 to Wi-Fi;
- Industrial transparent transmission DTU;
- Wi-Fi remote monitoring/control;
- Toy field
- Color LED control;
- Integrated management of fire protection and security intelligence;
- Smart card terminals, wireless POS machines, Wi-Fi cameras, handheld devices, etc

## 3. Example Use

### 3.1 Use Uno R3 and ESP-01 as server

**Tools**

**(1)**Prepare the hardware components as follows:

- Computer *1;
- UNO R3 development board*1;
- Esp-01 module *1;
- Square USB cable *1
- 2-cell 18650 lithium battery case with batteries *1

**(2)**Software: using arduino IDE.

**Connection**

Connect Uno R3 to ESP-01 module:

![](media/image-20260114160152022.png)

**Test Code**

```c
#include <SoftwareSerial.h>
SoftwareSerial mySerial(2, 3); // RX, TX
char OK[2]="";

//////////////////////////////////////////////////////////////////////////
void OK_config()
{  
  while(1)
  {
    OK[0]=mySerial.read();
    if(OK[0]=='O')
    {
      OK[1]=mySerial.read();
      if(OK[1]=='K')
      {
         break;
      }
    }
    delay(20);
  }  
}
//////////////////////////////////////////////////////////////////////////
void esp8266_config()
{
  Serial.println("AT+RST");   
  delay(1000);
  mySerial.println("AT+CWMODE_DEF=3");   //set the current Wi-Fi mode and save to Flash
  OK_config();
  mySerial.println("AT+CWSAP=\"KEYES_server\",\"123456789\",11,2");
  OK_config();
  mySerial.println("AT+CIPMUX=1");       //multiple connection   default port=333
  OK_config();
  mySerial.println("AT+CIPSERVER=1");    //build TCP Server
  OK_config();
  Serial.println("Initialize the server!");
  digitalWrite(13,HIGH);
  OK_config();                          //wait Client to send OK; access to Client
}
///////////////////////////////////////////////////////////////////////
void setup() 
{ 
  Serial.begin(115200);
  mySerial.begin(115200);
  pinMode(13,OUTPUT);
  digitalWrite(13,LOW);
  esp8266_config();
}

void loop()
{
 mySerial.println("AT+CIPSEND=0,9"); 
 delay(1000);
 mySerial.println("arduino"); 
 digitalWrite(13,LOW);
 delay(1000);
 digitalWrite(13,HIGH);
 delay(1000);
}
```

**Note:** The code USES the AT instruction of esp-01 to realize the required functions. Please refer to the specific AT instructions mentioned below.

**Use and Result**

- A、connect the UNO R3 main board to the computer via USB port with a square USB cable; then open the arduino IDE to upload the test code to UNO R3.
- B、Unplug the USB cable; connect the esp-01 module to UNO R3 main board using jumper wires according to the connection diagram.
- C、supply the power to UNO R3 main board via black DC power jack with 2-cell 18650 batteries; wait for a few seconds, LED labeled L on the UNO R3 will normally turn on. Otherwise, pull out the power cable and repower again.

### 3.2 Set ESP-01 as Client and connect server

**Tools**

**(1)**Prepare the hardware components as follows:

- Computer *1
- TTL USB to serial port module *1
- Esp-01 module *1
- Mini USB cable *1

**(2)**Software: using esp8266 debugging tool or USR-TCP232-Test debug tool.

**Connection**

Connect ESP-01 module to TTL USB-to-serial port module:

![](media/image-20260114160803349.png)**Detailed debugging**

- A、Follow the connection diagram to connect ESP-01 module to TTL USB-to-serial port module;
- B、Connect the TTL USB-to-serial port module to the computer using a mini USB cable.

<font color="red">**SPECIAL NOTE:** need to program the corresponding drive to the TTL USB-to-serial port module before use. </font>

- Open the USR-TCP232-Test debug tool, click![](media/image-20260114160940527.png)to select the language, select the proper USB port and set the baud rate to **115200**; set the Recv Options ![](media/image-20260114161005360.png)A、 , open the serial port. As shown below.

![](media/image-20260114161025617.png)

![](media/image-20260114161032892.png)

- D、**AT+CWMODE=3** set the ESP-01 module as mode 3:

![](media/image-20260114161056121.png)

Special attention:

**1 :** To fill in the instruction, a newline character should be added after the instruction is typed, as shown in the figure above.  All subsequent instructions should be operated in this way.
**2 :** To send instructions to esp-01.
**3 :** The information returned after the instruction is received by esp-01.

- E、AT+CWJAP="KEYES_server","123456789" connect to server ESP-01 WIFI:

![](media/image-20260114161241279.png)

- F、AT+CIPAP_CUR="192.168.1.20","192.168.1.20" modify the IP of client ESP-01 AP; modifying the IP of AP is to avoid the conflict between client AP’s IP and server AP’s IP. As figure shown below.

![](media/image-20260114161258858.png)

- G、AT+CIPSTART="TCP","192.168.4.1",333 connect to server ESP-01, as shown below.

![](media/image-20260114161320440.png)

- H、Send the AT+CIPMODE=1 command to set the client ESP-01 as pass-through mode. As shown below.

![](media/image-20260114161342347.png)

- I、Send the AT+CIPSEND command means the client ESP-01 send the data instruction to the server ESP-01. As shown below.

![](media/image-20260114161401190.png)

- J、client ESP-01 sends the “OK” character to server ESP-01; trigger the server ESP-01 to send the “arduino” character to client ESP-01 all the time. As figure shown below.

![](media/image-20260114161417009.png)

- K、At this moment, the LED labeled L on the UNO R3 main board connected to server ESP-01 will turn on normally, which illustrates it always send the data to client ESP-01.

## 4. Basic AT Commands

### 4.1 Test the AT

- **Syntax Rules:**

![](media/8.png)

### 4.2 WiFi Function AT Command

**Select WiFi Application Mode: AT+CWMODE**

- **Syntax Rules:**

![](media/9.png)

- **Parameter Definition:**

![](media/10.png)

**List out Access Point: AT+CWLAP**

- **Syntax Rules:**

![](media/11.png)

- **Parameter Definition:**

![](media/12.png)

**Add Access Point: AT+CWJAP**

- **Syntax Rules:**

![](media/13.png)

- **Parameter Definition:**

![](media/14.png)

**Exit Access Point: AT+CWQAP**

- **Syntax Rules:**

![](media/15.png)

**Set the AP Mode: AT+CWSAP**

- **Syntax Rules:**

![](media/16.png)

- **Parameter Definition:**

![](media/17.png)

### 4.3 TCPIP AT Command

**Build TCP/UDP Connection: AT+CIPSTART**

- **Syntax Rules:**

![](media/18.png)

- **Parameter Definition:**

![](media/19.png)

**Get TCP/UDP Connection Status: AT+CIPSTATUS**

- **Syntax Rules:**

![](media/20.png)

- **Parameter Definition:**

![](media/21.png)

**Start Multilink: AT+CIPMUX**

- **Syntax Rules:**

![](media/22.png)

- **Parameter Definition:**

![](media/23.png)

**Send Data: AT+CIPSEND**

- **Syntax Rules:**

![](media/24.png)

- **Parameter Definition:**

![](media/25.png)

**Close TCP/UDP Connection: AT+CIPCLOSE**

- **Syntax Rules:**

![](media/26.png)

- **Parameter Definition:**

![](media/27.png)

**Get Local IP Address: AT+CIFSR**

- **Syntax Rules:**

![](media/28.png)

- **Parameter Definition:**

![](media/29.png)

**Select TCPIP Mode: AT+CIPMODE**

- **Syntax Rules:**

![](media/30.png)

- **Parameter Definition:**

![](media/31.png)

**Set the Sever Timeout: AT+CIPSTO**

- **Syntax Rules:**

![](media/32.png)

- **Parameter Definition:**

![](media/33.png)

**Set the Baud Rate: AT+CIOBAUD**

- **Syntax Rules:**

![](media/34.png)

The default baud rate is 9600. 

- **Parameter Definition:**

![](media/35.png)

## 5. AT Command Settings

When setting the AT command, you should use a USB to Serial module, that is FT232 module, and a WIFI to serial shield.

Connect well and then connect them to your computer using mini USB cable.

![](media/image-20260114170554312.png)

Connected successfully, open the ESP8266 debugging tool, set the baud rate to 115200, click to open the Serial Port, and click Test the AT.

![](media/image-20260114170706110.png)

## 6. Firmware Programming

When setting the AT command, you should use a USB to Serial module, that is FT232 module, and a WIFI to serial shield.

Connect well and then connect them to your computer using mini USB cable.

![](media/image-20260114170802663.png)

Then open flash_download_tools_v3.6.5software, click to open![](media/image-20260114170815119.png).

![](media/image-20260114170852725.png)

Wait for a minute, pop up the below interface, click the ESP8266 Download Tool.

![](media/image-20260114171050532.png)

Pop up the interface to set the firmware burning. This is the address of firmware burning.![image-20260114171107256](media/image-20260114171107256.png)

![](media/image-20260114171113162.png)

Hold the **FLASH** button on the shield, and Tap **START** button, then press **RST** button on the shield, release the **FLASH** button. The module will enter the download mode. Shown below.

![](media/image-20260114171133654.png)

![](media/image-20260114171139246.png)

Firmware download completed, can enter the corresponding software to set the AT command.