6mmm/s - A compact, kinetic energy meter (sometimes referred to as "chrono") for pea, foam dart or airsoft toys.


  • compact size
  • modular system
  • forgot the rest...

Source code is now on Github (3/2013):

click me

(and there probably never will be any...)

In the meantime, grab what you'll need or get along!


6mmm/s and (optional) display unit
the DUTs
An early prototype...
...under fire

Aquisition Board

V1.1 schematic...
...and (an older) layout

to be written...

Display Section

V1.0 schematic...
...and layout

to be written...



Standalone/Display Mode

Interface Mode

6mmm/s does not need the fancy LCD and can be operated without it.
No matter if the display is attached or not, the unit always transmits the following data via its serial TX line, at 9600 bits/s, 8N1:

    v = <speed> m/s
    m = <mass> g
    E = <energy> J

Same with invisible codes included:

    v = <speed> m/s<CR><LF>
    m = <mass> g<CR><LF>
    E = <energy> J<CR><LF>

with the known substitutions:

   <CR> = 0x0D (13 decimal)
   <LF> = 0x0A (10 decimal)

Data reception ("RX") is not (yet) built in (and probably never will be in there).
It's not required. The receiving equipment needs nothing else but the velocity and should calculate the energy by its own...

Some Useless Pics

the IR LEDs

1.4g; Nerf whistler dart
need more space...

Do not forget to remove the RoHS stickers
BEFORE soldering the backlight...



- schematic (PDF)
- layout (BRD)
- mechanic (STL)
- firmware (HEX)
- source code
- ...

DOWNLOAD: 6mmms_hard_V11.zip Hardware, Acquisition Board, V1.1
DOWNLOAD: 6mmms-LCD_hard_V10.zip Hardware, LCD-Board, V1.0
DOWNLOAD: 6mmms_mech_V10.zip Mechanic (for 3D printers), V1.0
DOWNLOAD: 6mmms_firm_V05.zip Firmware, V0.5
DOWNLOAD: source code on Github stay updated
DOWNLOAD: old page

ASkr 07/2012: initial public release
ASkr 09/2012: uploaded HW V1.1, FW V0.5, mechanics, more images
ASkr 02/2013: removed some typos, added Github source code link