rosserial_arduino allows you to easily connect an Arduino or other serial device to the ROS runtime graph. All of node initialization and communication is handled through a NodeHandle.
Creation of a NodeHandle is quite easy, before your setup() function:
One of the first calls you will likely execute in a your Arduino setup() function is the call to initNode(), which initializes the ROS node for the process. You can only have one node in a rosserial device, so you can only call initNode() once.
The following example shows a complete example of how to initialize a node and process the serial data inside the loop() function:
Custom Hardware Objects
The rosserial_client library does not actually provide a NodeHandle object directly. Instead it provides:
ros::NodeHandle_<HardwareType, MAX_PUBLISHERS=25, MAX_SUBSCRIBERS=25, IN_BUFFER_SIZE=512, OUT_BUFFER_SIZE=512> nh;
All client libraries are expected to provide a Hardware object and implement the default node handle type, typically in a ros.h file. For more information on customizing the hardware object, see Adding Support for New Hardware