Pause print on GPIO filament runout sensor

The following need to be added to the config.yaml:

plugins:
  filament:
    pin: XX
    bounce: 400

where XX represent the GPIO pin where your sensor is connected.

An API is available to check the filament sensor status via a GET method to /plugin/filament/status which returns a JSON

• {status: "-1"} if the sensor is not setup
• {status: "0"} if the sensor is OFF (filament not present)
• {status: "1"} if the sensor is ON (filament present)

The status 0/1 depends on the type of sensor, and it might be reverse if using a normaly closed switch.

A build using an optical switch can be found at http://www.thingiverse.com/thing:1646220

Note: Needs RPi.GPIO version greater than 0.6.0 to allow access to GPIO for non root and chmod a+rw /dev/gpiomem. This requires a fairly up to date system.

WARNING: I am not responsible for any failed prints. Use at your own risk.

• Filament sensor no longer uses multiple processes. Only one process active the entire time.
• Communication improved between parent and child process
• Child process will die when parent process is no longer alive
• Filament sensor will respond to error events now