call WiFi.softAP(ssid) to set up an open network.WiFi.mode(m): set mode to WIFI_AP, WIFI_STA, WIFI_AP_STA or WIFI_OFF.This is mostly similar to WiFi shield library. Other libraries (not included with the IDE).mDNS and DNS-SD responder (ESP8266mDNS library).I2C or I 2C is short for Inter-Integrated Circuit, a synchronous serial communication protocol developed by Phillips for communication between a fast Microcontroller and relatively slow peripherals (like Memory or Sensors) using just two wires. Hence, it is sometimes also known as TWI (Two Wire Interface). Using I2C, you can transmit data at rates 100 kbit/s (clock 100 kHz – Standard Mode), 400 kbit/s (clock 400 kHz – Fast Mode), 1 Mbit/s (clock 1 MHz – Fast Mode Plus) and 3.4 Mbit/s (clock 3.4 MHz – High Speed Mode). This may not seem much but it is sufficient for interfacing sensors, memories and displays at small distances. The I2C Bus consists of two wires called the Serial Data (SDA) and the Serial Clock (SCL). Data is transmitted through the SDA line while the SCL line is used to synchronize the devices with the clock signal.īoth these bus lines are open-drain drivers and hence you have to use pull-up resistors to keep them HIGH.

There are two types of devices that connect to the I2C Bus: Master and Slave.

Bus Masters are responsible for sending and receiving data to and from the slave devices. The clock signal is also supplied by the master. I2C network supports multiple masters and multiple slaves (but we usually see single master and multiple slaves). Each slave device connected to the I2C bus has a unique 7-bit address. Using this address, master selects a particular slave for data transmission (send or receive) and the selected slave responds according to request. I made an extensive tutorial on basics of I 2C Communication. For more information on that, visit “ Basics of I2C Communication”. I2C in ArduinoĪrduino supports I2C Communication. If you take a look at the pinout of Arduino UNO from the tutorial “ ARDUINO UNO PINOUT”, Analog Input pins A4 and A5 have an alternative function of I2C.

The A4 pin acts as SDA while the A5 pin acts as SCL. In R3 of original Arduino UNO, there are two more pins near Digital IO Pin 13 (near the USB socket), dedicated to SDA and SCL.

#Find wire h library for arduino serial#.

Wire h arduino library download