Warning

This is the dev documentation for an unreleased version of MPF!

This is the documentation for MPF 0.56, which is the “dev” (next) release of MPF that is a work-in-progress. Unless you’re specifically looking for this version, you probably want to use the version of documentation called “latest” which is for the latest released version of MPF. That documentation is at docs.missionpinball.org/en/latest.

How to use Step Stick Steppers in MPF

Related Config File Sections
hardware:
step_stick_stepper_settings:
digital_outputs:
switches:
steppers:

MPF can drive steppers on a StepStick (or DRV8825) connected via a digital output. Depending on the jitter of the output the speed might be limited to a few steps per second (like 50-200).

TODO: Add a picture of a step stick or DRV8825

Overview video about steppers:

Configuring your stepper

A step stick stepper needs two or three outputs which define the hardware number: direction_output:step_output or direction_output:step_output:enable_output. In addition, you need a homing_switch so MPF can find the 0 position of your stepper at startup.

This is an example:

#config_version=5
hardware:
  stepper_controllers: step_stick
digital_outputs:
  c_direction:
    number: 1
    type: driver
  c_step:
    number: 2
    type: driver
  c_enable:
    number: 3
    type: driver
switches:
  s_home:
    number: 1
steppers:
  stepper1:
    number: c_direction:c_step:c_enable   # enable is optional
    homing_mode: switch
    homing_switch: s_home
    named_positions:
      10: test_00
      20: test_01
      50: test_10
    platform_settings:  # optional speed settings
      low_time: 20ms
      high_time: 20ms

This example is tested to be valid MPF config. However, it is not integration tested.

#config_version=5
hardware:
  stepper_controllers: step_stick
digital_outputs:
  c_direction:
    number: 1
    type: driver
  c_step:
    number: 2
    type: driver
  c_enable:
    number: 3
    type: driver
switches:
  s_home:
    number: 1
steppers:
  stepper1:
    number: c_direction:c_step:c_enable   # enable is optional
    homing_mode: switch
    homing_switch: s_home
    named_positions:
      10: test_00
      20: test_01
      50: test_10
    platform_settings:  # optional speed settings
      low_time: 20ms
      high_time: 20ms

You might want to change the speed in the platform_settings section. 1000 / (low_time + high_time) will be your number of steps per second.

Connecting your stepper driver

Connect the DIR pin to your direction_output, STP to your step_output and GND to your ground. If use an enable_output connect it to EN. Otherwise, pull it to GND or the driver will not work. Connect SLP and RST to VDD (not all driver have all of them). In addition, you need to pull M0, M1 and M2 to VDD or GND to configure the step resolution. Your stepper will connect to 1A, 1B, 2A and 2B. Connect power to VMOT (do not forget to also connect ground of your stepper power supply; see Voltages and Power). See the datasheet for details about your driver.

What if it did not work?

Have a look at our hardware troubleshooting guide.