How to configure mono/traditional DMD (P-ROC)

Related Config File Sections
dmds:
p_roc:

The P-ROC can drive a traditional single-color pinball DMD via the 14-pin DMD connector cable that’s been in most pinball machines for the past 25 years, like this:

../../_images/display_mono_dmd1.jpg

Note

If you want to drive an RGB LED DMD and you’re using a P-ROC, you can do that by adding a SmartMatrix or RGB.DMD board which you would then use in place of the P-ROC’s 14-pin DMD connector.

1. Connect your hardware

../../_images/physical_dmd_in_backbox1.jpg

2. Add a physical DMD device entry

Once you have your hardware and port set, you need to create the actual device entry for the DMD.

You do this in the dmds: section of the machine config. This section is like the other common sections (switches, coils, etc.) where you enter the name(s) of your device(s), and then under each one, you enter its settings.

(And yes, in case you’re wondering, it’s possible to have more than one physical DMD.)

To do this, create a section in your machine-wide config called dmds:, and then pick a name for the DMD, like this:

dmds:
  my_dmd:
     shades: 16

You need to have at least one setting for this to be a valid YAML file, so we usually just pick the shades and add that with a value of 16 (which means the DMD runs will convert the display content to 16 mono shades when it displays it).

The “shades” option is how many brightness shades you want. 1990s WPC machines supported 4 shades, and modern Stern DMD machines support 16. The P-ROC supports 16 shades (even on older 1990s plasma DMDs). Most modern games will probably be 16 shades, but you can do 4 (or even 2) if you want an old school look.

There are lots more options for the physical_dmd: section than just the “shades” option listed here. Check the dmds: for a list of all the options.

Note that one option you do NOT have for physical DMDs is the color. That’s because the color of the DMD is determined by the DMD itself. You don’t actually send it color values, rather, you just send it brightness levels, and the DMD shows those brightness levels with whatever color the DMD is.

3. Set a source display

Now that you have everything configured, the last step is to make sure the DMD knows what content to show. In MPF, you do this by mapping a physical DMD to an MPF display.

By default, the DMD will look for a display (in your displays: section called “dmd”. However you can override this and configure the DMD to use whatever logical display you want by setting a source_display: setting. (Just make sure that the width and height of your source display match the physical pixel dimensions of the DMD or else it will be weird.)

4. Setting the DMD update rate

By default, MPF will send new DMD frames to the P-ROC at about 30 frames per second. (Technically it sends a new frame every 33ms.)

5. Fine tuning the DMD timing cycles

The P-ROC is able to drive a traditional DMD with 16 shades of intensity, ranging from off (0) to full on (15). Note that the P-ROC doesn’t control (or even know) what color the DMD is as that’s dictated by the DMD itself.

The P-ROC creates the appearance of 16 levels of brightness by rapidly turning individual dots on and off.

For years, DMD’s have been high-voltage gas plasma displays, though more recently they’re LED-based (even the single color ones with the 14-pin connectors).

Some people have reported less-than-optimal quality when using a P-ROC with certain types of DMDs. To address this, the P-ROC allows you to fine-tune the timings of the individual bit planes that make up the image.

For details on this, you can search the P-ROC forums for “high_cycles” to find a few threads where people are talking about these settings. Then you can set them in the p_roc: dmd_timing_cycles: section of your machine-wide config, like this:

p_roc:
   dmd_timing_cycles: 90, 190, 50, 377

Note that we do not have specific recommendations for values here and based on our experience, we haven’t found a need to change this. However, if you do have issues and you get new values by talking to the P-ROC folks, this is how you adjust them in MPF.

Our recommendation is that you leave the dmd_timing_cycles: setting out of your p_roc: config unless you need it and really know what you’re doing. (There’s potential that bad values here could permanently damage your DMD hardware, so again, only change these if you know what you’re doing.)

A final config you can test

At this point you’re all set, and whatever slides and widgets are shown on the DMD’s source display in MPF-MC should be shown on the physical DMD.

That said, all these options can be kind of confusing, so we created a quick example config you can use to make sure you have yours set right. (You can actually just save this config to config.yaml in a blank machine folder and run it to see it in action which will verify that you’ve got everything working properly.)

To run this sample config, you can either run mpf both.

When you run it, do not use the -x or -X options, because either of those will tell MPF to not use physical hardware which means it won’t try to connect to the Teensy.

Note that the Using a traditional (single color) physical DMD guide has more details on the window and slide settings used in this machine config.

hardware:
  platform: p_roc
  driverboards: pdb

displays:
  window:  # on screen window
    width: 600
    height: 200
  dmd:  # source display for the DMD
    width: 128
    height: 32
    default: true

window:
  width: 600
  height: 200
  title: Mission Pinball Framework

dmds:
  my_dmd:
     brightness: 1.0

slides:
  window_slide_1:  # slide we'll show in the on-screen window
  - type: display
    effects:
     - type: dmd
       pixel_color: ff5500
    width: 512
    height: 12
  - type: text
    text: MISSION PINBALL FRAMEWORK
    anchor_y: top
    y: top-3
    font_size: 30
  - type: rectangle
    width: 514
    height: 130
    color: 444444
  dmd_slide_1:  # slide we'll show on the physical DMD
  - type: text
    text: IT WORKS!
    font_size: 30

slide_player:
  init_done:
    window_slide_1:
      target: window
    dmd_slide_1:
      target: dmd