rpi_gpio is a Dart library for accessing the Raspberry Pi GPIO pins.
Gpio provides a high level API for accessing the various General Purpose I/O pins on the Raspberry Pi.
RpiHardware provides a low level API for accessing the GPIO pins.
The rpi_gpio library accesses the GPIO pins using a native library written in C and built on top of the wiringPi library. For security reasons, authors cannot publish binary content to pub.dartlang.org, so there are some extra steps necessary to compile the native library on the RPi before this package can be used. These two steps must be performed when you install and each time you upgrade the rpi_gpio package.
1) Activate the rpi_gpio package using the pub global command.
pub global activate rpi_gpio
2) From your application directory (the application that references the rpi_gpio package) run the following command to build the native library
pub global run rpi_gpio:build_lib
pub global activate makes the Dart scripts in the rpi_gpio/bin directory runnable from the command line. pub global run rpi_gpio:build_lib runs the rpi_gpio/bin/build_lib.dart program which in turn calls the build_lib script to compile the native librpi_gpio_ext.so library for the rpi_gpio package.