Jogging a 3d printer with a gamepad.

Options

Usage: ./machine-jog <options>
  -C <config-dir>  : Create a configuration file for Joystick, then exit.
  -j <config-dir>  : Jog machine using config from directory.
  -n <config-name> : Optional config name; otherwise derived from joystick name
  -i <init-ms>     : Wait time for machine to initialize (default 20000)
  -h               : Home on startup
  -p <persist-file>: persist saved points in given file
  -L <x,y,z>       : Machine limits in mm
  -x <speed>       : feedrate for xy in mm/s
  -z <speed>       : feedrate for z in mm/s
  -s               : machine not connected; simulate.
  -q               : Quiet. No chatter on stderr.

Joystick Configuration

First, create a configuration for your specific joystick. Since each joystick has its own mapping of axis and buttons, we need to first tell machine-jog where these are. This will ask you to move the joystick to get the right axis and button mapping:

mkdir js-conf
./machine-jog -C js-conf/

The directory will contain a configuration with the name of the joystick. That way, it is possible to have different configurations depending on the joystick name.

The configuration asks you to move the X,Y,Z to their extreme values to learn which is your preferred joystick axis. Also it asks you for the button you want to use as the 'home' button (typically there is some center button). (All other buttons will be used to store and retrieve positions).

Typically all USB gamepads either for PS3 or Xbox should work. On my beaglebone I found that the xpad kernel module was missing (this was in 2014, so might work by now), so only a PS3 gamepad worked right out of the box. On my regular Linux notebook, both types worked right away.

Wire Up

For best flexibility, machine-jog communicates via stdin/stdout with the machine, which means you need to 'wire up' this communication with the machine. For instance, if your machine is connected via a terminal line (very common), you can use socat to wire it up:

socat EXEC:"./machine-jog -j js-conf/ -x 120 -z 50 -h -p savedpoints.data" /dev/ttyACM0,raw,echo=0,b115200

This tells socat to execute the machine-jog binary with the joystick configuration and connect its stdin/stdout to the /dev/ttyACM0 terminal with a bitrate of 230400. If you use BeagleG, then you'd connect it to the TCP socket:

socat EXEC:"./machine-jog -j config/ -x 100 -z 20 -p savedpoints.data" TCP4:beagleg-machine.local:4000

This could be automatically started in a udev-rule for instance.

The typical use-case, however, is to use machine-jog from within another program that already has the serial line open and 'owns' it. In this case, that program would start machine-jog in a sub-process and send everything from its stdout stream to the printer and back from the printer into stdin of the process. Make sure to not do any buffering. (This would be awesome in OctoPrint; if it sees /dev/input/js0 to exist, it could subprocess.call(...) machine-jog and connect the streams when the user is in the control panel, so that both, the manual jogging buttons and the joystick works. Should be fairly easy to add for someone who knows Python...)

Use

To move around, use the joysticks to manipulate x/y/z. The speed of movement is proportional to the deflection of the joystick. Hitting the limits of the machine (if given with -L) is fed back with a short rumble (if supported by gamepad).

To 'store' a current point in one of the six memory buttons, just do a long-press on the button (acknowledged by a short rumble). A short-press on that button will go back to that position.