• I2C is protocol that allows two devices to talk to each other using only two buses: a clock one (SCL bus) and a data on (SDA bus). It can allow up to 127 slaves connected to one master to exchange information. It is a very common protocol for Arduino as it is used to communicate with various sensors. There is a dedicated library called Wire in Arduino that you can readily use.
  • SPI is a synchronous serial communication interface specification used for short distance communication, primarily in embedded systems. It uses four buses: clock (SCK), two data lines (MISO: Master Output Slave Input, MOSI: Master Input Slave Output) and a select line(SS) to choose among the multiple slave devices.
  • Noduino is a JavaScript and Node.js framework for accessing basic Arduino controls from web applications using HTML5, Socket.IO and Node.js.
  • UDP
  • MQTT