manual.md

Edrumulus User Manual

Edrumulus is a high quality open source e-drum trigger module software. To use Edrumulus, you need to have:

• a supported micro controller developer board (see the README file for supported micro controllers),
• an analog front end circuit to connect the trigger pads to the micro controller (either a bread board is used or soldering skills are needed),
• the Arduino or PlatformIO IDE for flashing the micro controller firmware,
• Python to control Edrumulus trigger parameters in real-time.
  • Install the Python PIP packages python-rtmidi and windows-curses.

Analog front end circuit

If Edrumulus is installed on the micro controller and there is no analog front end circuit attached, you will get a lot of false triggering (i.e. a lot of MIDI notes). For the Edrumulus system to work correctly, all configured ADC inputs must have the analog front end circuit attached.

If an analog front end for a configured input is missing or faulty, Edrumulus will report a DC offset error.

Setup for ESP32

Install the Arduino IDE and add the ESP32 Board Manager according to this linked description. Now open the edrumulus.ino file in the Arduino IDE and compile and upload.

Use Edrumulus in your DAW

Go into edrumulus/tools directory and start edrumulus_gui.py. This tool will connect to Edrumulus and creates (virtual) MIDI ports which can be selected in your DAW as a MIDI device. This tool works on Windows, Linux and MacOS.

E.g., on Linux simply type python3 edrumulus_gui.py. If you have an ESP32-S3, this usually is on a different serial port than the normal ESP32. E.g., for an ESP32-S3 on Windows, the following command should work: python edrumulus_gui.py serial COM4.

Hardware-specific comments

How to support new pieces of hardware

1. Start with prototype 2 and optimize the analog circuit. Random testing or a simulation with software like LTSpice could be used.
2. Analyze the samples in the Octave model to identify the edrumulus parameters:
   • Attach the pad to a normal sound card and record the strikes with 8 kHz sampling rate and according to https://github.com/corrados/edrumulus/blob/main/doc/algorithm.md#test-signals.
   • Add the recording to https://github.com/corrados/edrumulus/tree/main/algorithm/signals.
   • Create a new type in https://github.com/corrados/edrumulus/blob/main/algorithm/signalsandsettings.m and use an initial parameter set from a similar pad as a starting point.
   • Call the script signalsandsettings.m in Octave which automatically uses the script drumtrigger.m.
   • Adjust the parameters so that the decay curve looks ok and try to get as little false triggers as possible.
   • The updated parameters are then used in https://github.com/corrados/edrumulus/blob/main/edrumulus_parameters.cpp.
   • To get it fully working, the new type has to be added at multiple places, e.g. in the GUI python script, too.
3. Test the parameters in practice. Modify the available real-time parameters for hopefully better results. Possibly go back to previous steps.

Millenium MPS-750X

• Recommended circuit: Rs=10k, Rp=10k, Cp=0.
• TRS pins:
  • Toms: hit piezo = T, rim piezo = R, GND = S.
  • Cymbals including Hi-Hat: Bow piezo = S, Rim switch = R (none for Hi-Hat), GND = T.
• Ride and crash cymbals draw some current.
• The ride rim switch differs from the ride bell switch by a 5k resistor.
• Set all MPS750X potis to maximum output with a screw driver (sometimes the direction appears to be indicated incorrectly).