The OneTrickPony MIDI Controller

As the question Pops up frequently how to trigger the Shruthi while tweaking without having to connect a bulky MasterKeyboard or something else i quick and dirty made this:

A simple Microcontroller (here a PicAxe 08M2) that scans a Button, if pressed it sends a NoteOn Message with a Note Number determined by the Pots Setting (hey, you want to check your Patch at different Notes, don’t you?), if releases sends a corresponding NoteOff Message. Its as simple as that, a OneTrickPony.

You can find Sourcode (that compiles to 80 Byte ;-)), Schematics and further Information here

Before you ask: Im not gonna do Kits or PCBs or Cases as this thingie is so simple everybody can do it on a piece of PerfBoard (its just 1Cap, 5 Resistors, a LED, a Pot and the MIDI-Connector…) but if anyone is interested ill send you a programmed PicAxe Chip and you can do your own OneTrickPony…

that’s very cool :slight_smile:

As used in the one-trick poney, i’d rather suggest that it sends a NoteOff message when pressed again. It’s more practical using the ARP or SEQ setting than the ARP+lt or SEQ+lt.
Or, we can leave the option up to the user…

Or you can choose at startup between these Programs

  • Note On/Off like a 1Key Masterkeyboard + Pot for NoteNumber
  • Latched + Pot for Notenumber (turn the Knob while latched and it sends a NoteOff for the old and NoteOn for the new Note)
  • Chords (plays arpegiated Chords, latched, Pot scans thru different chords: C, Cm, Csus2, Cmaj7, C7/9 etc…)

Then you’ll have to rename this to the 3TricksPony™

Hmmm, this poney is starting to learn too many tricks :slight_smile:

nice :slight_smile: i am sure this would fit inside the shruthi case, if build very tiny.
i am just not sure, if the controls would fit.
…button, pot + it would need an extra switch to be able to detatch it from the midi in.

Maybe something based on a tiny accelerometer? Is my shruthi broken? (shake it… test tone) No it’s not!

in my opinion, if you want to fit it into a shruthi case, you better use directly the IN1 to IN4 ports?


You can go without the Pot if you like, then you only have one Key…

Just checked, i can disconnect the HardwareSerial In Port so i have another free I/O Pin. Lets give the accelerometer a try…

Just fit a piezo transducer in the case. Tap the box to play a sound :slight_smile:

naah, you cant sell this to the bay area or japan…

“photoshopped one trick pony logo with an infinity sign instead of a one”
“photoshopped one trick pony logo with 1111 instead of a one” + “it’s the 15 tricks pony (in binary)”

i could use the spare pin for a serial lcd…

or perhaps some 7-segment displays for note number readout?

Frank, you’re the man!

Thanks schrab; 1 Key seemed to be within my reach :wink:

@ fcd72

I need something almost exactly like this, but instead has a center detented pitch wheel and a midi thru or combiner or something. Basically to add a pitch wheel to a non-pitch wheel having midi keyboard. Chain the two together and boom, easy fix. How hard would it be to modify the code to do this? And how hard would it be to add a midi in + merge?


“I need something almost exactly like this” - but indeed totally different. The only thing in common would be that both need 5V Vcc :wink:

For the PicAxe Series of Chips you would have to

  • use an external A/D for 14Bit accuracy or at least significant more than the 8 Bits the PicAxe provides, probably connected via i2c that collides a bit with the Hardware Serial Out used for MIDI - there is only 1 UART. I have never tried the 10 bit input command (readadc10) for using enhanced internal resolution so i can’t really tell about if that works or not.
  • adding a useful internal MIDI Merge is not that easy as it would not only to pass thru bytes, it has to keep track of the running status so you don’t scramble up Data when merging your PitchBend Whee Data and it has to do useful SysEx forwarding…but its doable (i know because i did it :wink: )
  • add a 6n137 for the MIDI in + some Rs Diodes, Caps, a Proper PSU - so it grows to a real Project…

Using a 20X2 or bigger chip will probably do, but - I’m hopefully not to rude saying this now -please don’t ask me for doing this. Instead get y PicAxe Development Kit yourselves, ill gladly share my MIDI related Code. Or just buy a DOEPFER Wheel Electronic + Wheels.

And " something almost exactly like this " but whith 7 micro switch ( A B C, Do Ré Mi ) Instead of potentiometer ? it is also totally different ?