USB to TTL converter is not required.Compatible with r3 configuration, call syntax.10 support pwm / interrupt / serial port / i2c scalable gpio.You can the expansion board or custom firmware with r3.Colour: blue size: 70*40mmMaterial: metal Onboard four LED displays the status of ESP8266,namely PWR, DFU, STA, Use stackable design,it can continue to accumulate the other modules on it, easy to use. Onboard ESP8266-12 stable industrial gradeWiFi module with a metal , immunity to interference. using an enhanced PCB antenna, signal better. Built-in 5V to 3.3V TTL level converter to prevents high voltage TTL levels from causing damage to the WiFi module All interfaces of the onboard are standard-spaced for easy development by the . Standard pin interface to achieve full compatibility with the pitch for , and so on.(Unless the standard size for , such as for Nano, Mini) Using DIP switch can be used to quickly switch ESP8266-12 modle industrial- stable WiFi module operating mode (such as operating mode and upgrade mode) module, integrated serial chip, quickly brush the firmware. Using advanced 3.3V power supply chip (with the expansion board power chip CC3000 same),so the provided 3.3V voltage by board is more ,So the ESP8266 work as normal like cc3000 chip, there is no space. of application: Remote control electrical/model/four axis, etc For the smart devices networking services Household temperature/humidity/PM2.5 monitor, etc Intelligent switch etc. Package Included: 1 x Development BoardNote: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.