Gravity: IO Expansion Shield for Arduino v 7.1

Fast robotics prototyping made simple thanks to this expansion shield. No need of soldering and wiring, things that often becomes an issue when a bridged connection happens and components break. Often, without this solution, robot prototyping or electronics DIY becomes a very long term project. The DFRobot Expansion shield introduced to the market the famous color code for sensors and actuators input and output. The 3 pin format for Signal, Voltage and Ground is extremely useful, specially if used altogether with our increasingly large range of modules, sensors and devices that just fit. Alternatively, the board includes power input for salvaged power supplies or laboratory power supplies. Very common Xbee socket for multipurpose wireless connectivity such as RF, wireless, bluetooth.  The new version includes a voltage hardware setting through a jumper to allow compatibility with a bigger range of components at 3.3v. It also includes a Servo external power, with a protective diode. T