# 14.2 Wifi - ESP8266
## Option 1: Use ESP8266 With Arduino UNO R3
As in [**14.1 Serial**](/arduino-full-stack/14_communication/01_serial.md), an **ESP8266** Wifi module has been connected to the virtual serial pin 10 and pin 11 on Arduino UNO. In this section, we'll talk about how to use this **ESP8266** Wifi module a bit more.
**Note**: A lot of pictures in this section are directly cited from .
An **ESP8266** wifi module is provided in our Arduino course on-site, which looks like:
And its pins are defined as:
## Hardware Wiring
We still use the same hardware wiring way as in [**14.1 Serial**](/arduino-full-stack/14_communication/01_serial.md) to wire the Arduino UNO and ESP8266.
## Sketch
The same sketch in [**14.1 Serial**](/arduino-full-stack/14_communication/01_serial.md) is also adopted here.
## Mobile APPs
## Option 2: Use ESP8266 without Arduino Board
It is also possible to run the sketch on the **ESP8266** program without using an **Arduino UNO board**, for **ESP8266** comes with a MCU inside the module itself.
* detailedly explained how to do that step by step. Three cannonical examples are given on :
* [Blink](http://www.arduinesp.com/blink)
* [Wifiwebserver](http://www.arduinesp.com/wifiwebserver)
* [Thingspeak Temperature Sensor](http://www.arduinesp.com/thingspeak)
Students are encouraged to finish all examples after class.
* You can also refer to .
Both websites adopt Arduino IDE to implement/verify/compile the sketch, and flash/download the binary code onto an ESP8266 via Arduino UNO R3 board. Let's just see how it goes.
**Note**: You do need a FD232RS as a proxy/bridge, which looks as follows:
### Preparation
In order to flash sketch onto **ESP8266** via an Arduino board, we need to follow the steps on .
### STEP 1 - Install Arduino Core for ESP8266
**Note**: Make sure you enabled **python2**, instead of **python3**.
```
$ cd /opt/arduino/hardware
$ mkdir esp8266com
$ cd esp8266com
$ git clone https://github.com/esp8266/Arduino.git esp8266
$ cd esp8266/tool6s
$ python get.py
Platform: x86_64-pc-linux-gnu
Tool esptool-0.4.9-linux64.tar.gz already downloaded
Extracting dist/esptool-0.4.9-linux64.tar.gz
Renaming esptool-0.4.9-linux64 to esptool
Tool linux64-xtensa-lx106-elf-gb404fb9.tar.gz already downloaded
Extracting dist/linux64-xtensa-lx106-elf-gb404fb9.tar.gz
Tool mkspiffs-0.1.2-linux64.tar.gz already downloaded
Extracting dist/mkspiffs-0.1.2-linux64.tar.gz
Renaming mkspiffs-0.1.2-linux64 to mkspiffs
```
### STEP 2 - Add Additional Boards Manager URLs
Start **Arduino IDE**, then click **File->Preferences->Settings**, fill into **Additional Boards Manager URLs**, as:
### STEP 3 - Board Manager
Then, restart **Arduino IDE**. Click **Tools->Board->Board Manager**, then we search **esp**, make sure **Arduino AVR Boards** and **esp8266** are installed. Please refer to the following image:
**Note**: Without the installed Arduino AVR Boards, you will possibly meet the following **ERROR** message:
**SPIFFS Not Supported on avr**
What is **SPIFFS**? For short, it is **SPI Flash Filing System**. For details, please refer to .
Afterwards, we select **Tools->Board->Generic ESP8266 Module**.
### STEP 4 - Sketch Upload ERROR
After we selected **Board: "Generic ESP8266 Module"**, we are now trying to upload (after verify/compile) any sketch (here, the default **EMPTY** sketch for testing) to **Arduino board** with **ESP8266** **connected**. You will see the following **ERROR** messages:
```
warning: espcomm_sync failed
error: espcomm_open failed
error: espcomm_upload_mem failed
SPIFFS Upload failed!
```
By clicking **Tools->ESP8266 Sketch Data Upload**, you will see the following dialog:
By clicking **Yes**, the same **ERROR** messages will be given as:
```
[SPIFFS] data : /tmp/untitled321754874.tmp/sketch_mar24a/data
[SPIFFS] size : 64
[SPIFFS] page : 256
[SPIFFS] block : 4096
[SPIFFS] upload : /tmp/arduino_build_782393/sketch_mar24a.spiffs.bin
[SPIFFS] address: 0x6B000
[SPIFFS] reset : ck
[SPIFFS] port : /dev/ttyACM0
[SPIFFS] speed : 115200
warning: espcomm_sync failed
error: espcomm_open failed
error: espcomm_upload_mem failed
SPIFFS Upload failed!
```
So, it seems we failed to flash our **ESP8266** Wifi module. But, we have to do something. This website is just to solve this problem.
### STEP 5 - Flash ESP8266
In fact, 4 different methods have been summarized in to fulfill the task how to flash **ESP8266**.
* Flash Mode: “DIO”
* Flash Frequency: “40MHz”
* CPU Frequency: “80 MHz”
* Flash Size: “1M (64K SPIFFS)”
* Debug Port: “Disabled”
* Debug Level: “None”
* Reset Method: “ck”
* Upload Speed: “115200”
## Option 3: Official Arduino Wifi Shield
You can also purchase an **Arduino Wifi Shield** recommended by official Arduino website(s), and accomplish Wifi communication. Please refer to the following official Arduino webpages:
*
*
*
*
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