The following diagram shows sequence from startup to shutdown of dio_ros_driver.
User can startup dio_ros_driver with roslaunch command, and dio_ros_driver is terminated with SIGTERM signal.
dio_ros_driver is activated by user's launch request.
During startup, dio_ros_driver initializes DIO chip, though it is GPIO chip,and lines to access.
dio_ros_driver will shutdown the process after receiving SIGTERM signal. dio_ros_driver resets all DO ports with initial value. dio_ros_driver releases all ports from accessing resource, and close DIO chip. Finally, dio_ros_driver exits its' own process.
It means that dio_ros_driver has mainly 3 states: initting state, running state, and terminating state. dio_ros_driver class has methods which runs on each state.
dio_ros_driver reads values from selected ports periodically. The reading period is defined by access_frequency.
The sequence of DI port read is very simple. The main sequence is invoked by timer. When timer reaches predefined time, dio_ros_driver reads values from DI ports, and returns this value to Autoware (ROS node) by publishing topic.
dio_ros_driver checks status of ports and send the result to Autoware as /diagnostic
dio_ros_driver receives DO access request from Autoware (ROS node). dio_ros_driver sets value to a selected port according to the request. As well as sequence for DI access, dio_ros_driver sets value periodically while it can receives the request always.
dio_ros_driver checks status of ports and send the result to Autoware as /diagnostic
