PControl Modular Part#3

Its been a long time since the last post but I’ve been working on it again in the last 3 months.

Everything is tested but the MIDI part and everything works fine so far.

Here is the current 20-loop prototype (backside):

From top to down and left to right:

  • OLED Display 128x64px
  • Power distribution PCB (9V in, 6x5V out, 1×3.3V out)
  • PCM Control board
  • 3x PCM extension board




Things to do:

  • Verify MIDI functions
  • Change processor to a version with more programming memory (The fonts for the graphic display are a little large compared to the rest of the code)
  • Remove some bugs from the code that have to do with storing information
  • Do documentation ! 🙂
  •  …

While working on the code the final specs come to light:

  • Full modular design
    • auto detection of display type
    • auto detection of extension modules connected
    • piggiback mounting of control boards (switches and indicators)
  • Minimum solution has 5 loops, expandable in steps of 5 up to 20 loops
  • There are three display variants at the moment
    • 3 digit 7-segment LED
    • 132×32 LCD Module with backlight (DOGM-132)
    • OLED 128×64
  • 120 presets that can be organized as
    • 24×5
    • 12×10
    • 8×15
    • 6×20
  • Each preset stores
    • 20 loops
    • 12 letter preset name
    • 16 bytes of midi data to be sent
  • Switching options
    • Tuner out
    • Mute while switching (configurable mute time)
    • standard loop-switch
    • opto loop-switch
    • amp selector
    • amp channel switching (TS/TRS)
    • loop order switcher
    • stereo option
    • switching of “before amp” effects and “amp send/return effects” in one setup
    • MIDI switching of external effects and amps
      • Program Change (selectable channel and program)
      • Control Change (selectable channel, control and value)


Adding a few more pictures:

Please be aware that the images show prototyping at its best, so I added a few more connectors and things than needed on the final version 🙂

Control board:



Extension Board:




7-segment and control board:



Pigyback mount of Control board and Display board:




external LCD module 132×32:




External 7-segment Module:


7seg_ext 7seg_ext_back


Extension-Control board:





The design is working well but I need more programming memory to do some really nice editing features on the graphic displays.

Because of this and a few other things I decided to do new layouts for the Controller, Extension and Display-Boards.

Upcomming post#4 will show what I came up with on Eastern.