• This was discussed somewhere else. I’m learning SMT soldering, and maybe you can join me so we will no longer look like monkeys putting sticks in holes.

    I looked for SMT kits and the only thing I found was a sparkfun Simon game which appeared to have outdated documentation and some bad reviews. So I thought that I would design a “toy” circuit – something on which I can practice so no overtly complicated, but still useful. Also, this thing could help me learn about the process of having stuff manufactured – I’d rather blow money on a batch of 50 botched “toys” than 10x more expensive botched “upcoming mutable instruments product”.

    Any idea of small musical thingies you’d want to have? The thing should not take more than 1 day to design, and no more than 1 day to write the firmware for. I’d prefer something with an AVR inside because I need practice on TQFP packages.

    One example I did to practice SMT board layout: Midi events generator with 16 0-5V inputs

    But then so many people are doing these “MIDI CPUs” (highly liquid, Livid, Midibox) boooooring.

    Any other idea?

  • an gekko like arp with some leds and the arp software from the shruthi?
  • @fcd72, cool idea! but it’ll be battery powered, not MIDI bus powered – I’ve heard the gecko has problems with recent hardware whose MIDI output is too weak.

  • Digital filter (standalone version) ?
    Mini sequencer arp thingy with no frills, simply 16steps & a note selector ..
    Maybe a waveform analyzer ?(Not hose expensive thingys, just something that displays a simple waveform on a cheap graphic display of sorts)

  • yeah olivier, lets resurrect the gekko line, powered with 9v battery - the mutable instruments lizard ;)
  • MIDI merger to MIDI USB :D, with an 8u2 Atmel chip….

  • Easy.. Blikinlightz midi data display!

    Something like this, but in diddy SMT form, with a french twist.

    Who doesn’t like Blinkinlightz!??

  • I second EATYone’s idea. An Usb midi interface using an atmega 8u2 would be great.

  • Sorry, from the requirements: and no more than 1 day to write the firmware for

  • 8u2 firmware for a usb midi hid device is already available.

    There are several firmware version made for the arduino, but I don’t see why they can’t be used standalone: hiduino or this one.

  • +1 for a programmable arp. There is nothing anywhere similar the gekko or cyclone

  • I’d have thought a USB midi interface would offer no real challenge?
    Ever looked inside one? There is not much in there.. And if there is already working firmware, then where is the fun in that for Olivier?

    > Sorry, from the requirements: and no more than 1 day to write the firmware for

    I saw that. But I imagine few of us have much of an idea what goes into coding and how long it would take?? (Although you did zip your way through the digi effects board firmware pretty quickly it seemed?)

  • Regarding the USB interface:

    • yes, there’s already code out there, but I have never coded USB drivers before and I will never, ever, sell a product that include something I don’t understand inside-out. So there won’t be any product with USB before I take the time to learn it properly — even if in the end I acknowledge that library X or library Y is well written and does a perfect job. I’ll never get someone else’s code and stick it on a device unless I am confident that a/ I could have done it myself ; 2/ the code is of quality/efficiency good enough to justify not writing it myself (and for that I need to have a good grasp of what it does).
    • There’s a requirement that was implicit but I forgot to mention: even if the purpose number 1 is learning, it should have some potential to be turned into a product – especially if I use this as a subject for experimenting with manufacturers. There are so many existing MIDI/USB interface, including some with superior specs (the midibox 5X thing) that I don’t see why anyone would bother with the Mutable Instrument “Metoo MIDI USB”.

    I like the arp idea :)

  • an arpeggiator would be nice indeed. but what can be done in one day? variable gate length?

  • Yeah it can be done in one day. I can add as many options as you want, but what do you want in terms of UI? In terms of board size I want the thing to be about 1/4 the size of a Shruthi digital board.

  • hehe i want it all! is there an easy way to make expansion possible?
    you know, off board, so that one could add direct controls for things.
    but generally, programmable gatelength per step would be great, pattern programming, maybe velocity, i don’t know… right now.
    ...time to think!

  • If this continues like this, the SMT toy will become a Midibox SEQ v5. With 64 knobs, USB and a VCO :)

  • :D
    i just thought: sending portamento on/off for individual steps?

    menu only is fine too ;)

  • Ready for ridiculous?

    How about a toy/game/learningtool that was kinda like Simon but instead of the random call and mimic/speed-up you play a programed melody. It was an idea I had while working on my case(it's comparable in size to a candy machine, little smaller). The idea was that at the owner of the machine would program a melody into the device and hang it on a wall somewhere kinda inconspicuously and a passerby would notice it, insert a coin and be presented with a melody. There could be a keyboard or buttons or x/y type interface but simple and small(one my case its ribbon controls). So the player would have to play back the melody in order to get the candy/prize/location of next box to unlock/Shruthi-1 part(its the increment payment plan-you and your buddies collect and trade parts to complete a fully functioning device).There could be devices all over town all playing a different parts to one song or something. I kinda forgot about that idea until this thread. Funny.

    Anyhow, it could be used by students and teachers.
  • @rosch. The thing is, what I am looking for is the opposite – not something I would micropolish with 32 options and this and that controllable by CC and extra CV inputs and a debug serial interface, because I know I’d want to push it and implement every possible option to fill the code space. Something that serves one function – a useful one – without needing more than, say, 4 parameters to be set, and that won’t give me the feeling it is incomplete because only 50% of the code space of the AVR is used.

    Some more ideas:

    • a sine or square wave poly synth (say 4 voices). Just the raw oscs, only 2 or 3 settings (waveform, vibrato), send that to pedals / effects / your Shruthi…
    • very simple drum pattern generator, 4 instruments, each octave of a keyboard controls an instrument, each key in the octave triggers a different pattern. Only one control: tempo
    • a MIDI FX (delay, randomizer, transpose) with 16 or so preset. No edit!
    • I also like the Midi Monitor thing, though there won’t be much variety soldering 24 LEDs and resistors and shift registers…
    • Something that would be called “Captain Capybara”

  • I talk about USB hid midi device, ‘cause i’m working on it right now…For the seq if it has to be very small, why not an euclidian one Like this soft one:


    No many knob or Button are needed, for a great result :)

  • @ K&D. Hey, maybe there’s something worth doing in the “ear training” help department… Something that plays 2, 3, 5 notes with different difficulties (octave spread, rareness of interval). with 3 or 4 RGB LEDs showing your results over different time spans (last challenge, today, last week, last month)...

  • Euclid stuff is a good idea! Something that sends MIDI notes on channel 10 or with a few built in sounds?

    After all, Korg sells Monotribes with 3 preset drum sounds and they seem to do fine :)

  • I’ve been messing about with that Euclidean sequencer for a few days now. It’s brilliant! Im glad he turned it into a standalone app, so I can route it to Logic and my hardware toys (Actually I was using it with a Shruthi-1 the other day).

    I can’t see how it would be implemented in hardware though!? Least of all in something that takes 2 days to design/code.

    While we’re on the subject of odd ball sequencers. I seriously like this:

    At first it looks like yet another ‘Tenori-on in flash’ rip-off. But it isn’t… It does a pretty cool generative sequencing thing too. Well worth checking out.
    Shame it’s flash only though.. But perhaps he’ll build on it yet.

    I’d do some serious leg humpage for a hardware version of it! However, I know im venturing well off Oliviers plans for this project now, so i’ll stop harking on about it! ;)

  • :)
    i’d buy each of the aforementioned devices from you, should you make them. they sound all very interesting.
    i don’t know about Captain Capybara, but it’s a funny name!
    now off, got to hurry a bit, will re read this whole thing later!

  • @Luap: One way to do the Euclidian sequencer with only a tempo knob and a MIDI in:

    Octave 1 is kick
    Octave 2 is snare
    Octave 3 is hi-hat

    You start a pattern by playing a 2 notes chord. The lower note is the number of elements, the upper note is the size of the pattern (C = 1, C# = 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16). You kill a pattern by playing a single note. I’m pretty sure it would be easier to remember patterns that sound well using the 2 notes that encode them, rather than the 2 numbers.

  • That does sound doable :) (Even if I do like trippy GUI’s) With the software, you can also offset each pattern against another. I guess you would achieve that by simply offsetting when you hit the required keys?! It seems like one of those things that would make a lot more sense when you try to actually use it, than it does to describe it.

    (Ok whats up with the capybara thing? It’s like, staring at me.. As if it thinks I was the one that shaved it’s left leg or something)

  • Also, anybody here using a Minicommand?

  • Thinking of extenting the MIDI arpeggiator idea, how about a random chord generator ? There lots of stuff that could be used from the Shruthi, like the ragas for example, or am I wrong ?
    Button 1: Play chord
    Button 2: Randomize Chord
    Encoder / Pot: chord complexity (the higher, the more complex, i.e. more notes

    Overall idea: something that you don’t really know what’s coming out, but can be used for inspiration ?

  • My favourite arpeggiator is probably qmidiarp (Yep, I’m running Linux).
    You make a pattern with a string, for example: ‘>>1-0+<00p-2-d1+h1’

    >/<=double/half speed
    0-9=note in queue
    +/- =octave up/down
    d/h=double/half note length

    Maybe one could program that little device by pressing a button, programming the pattern with notes which are mapped somehow, pressing the button again and it’s active.
    It would have to sync to midi clock of course.

  • My suggestion – one annoyance I’ve had in my studio for ages is that Roland JD-800 keyboard sends MIDI active sensing messages all the time. These active sensing messages are useless to me, and I want to filter them out. I looked for standalone little boxes for ages that would do this and nothing else. I don’t think it exists. I looked into building a MIDIbox thing to do it, but it seems like overkill.

    Does this fit the desired use case at all?

  • To summarize, a small box with a MIDI in, a MIDI out, some sort of minimal input device (pair of switches or clickable encoder), powered by batteries (2 x 1.5V or 9V??) some sort of minimal display (LED or 1x8 LCD) and that would run simple one-purpose firmware, upgradable through MIDI.

    List of firmwares:

    • arpeggiator
    • chord memory
    • MIDI euclidian pattern generator
    • 0xFE filter (this one is going to be tricky to code!)
    • ear training game
    • MIDI volume knob :D (sends volume CC)
    • MIDI clock generator
    • “Firmware of the week”

    Sort of stripped-down minicommand?

  • ^ Im not familiar with the minicommand. But still, that looks like a better idea than any 1 trick box. With a small LCD, it might even be some use as a midi monitor also?
    1 stone, many dead birds!

  • Yeah it can do MIDI monitoring too. I was thinking of a 8x1 LCD like this:

  • So go go go LOL, we all need this!

  • MIDI clock generator”

    Now thats something that would definately interest some people outside the DIY sphere (given that it’s rock solid and stable and has “that MPC groove” of course ;-) )

  • I know I am late to this but a couple projects that would be cool would be these:

    simple drum triggers to midi
    an uber tiny 1 channel either TB or TR sequencer

    something involving a artificial neural network!

    that arp sounds sweet though, and especially the euclidean pattern generator!

  • Your list is killer Olivier!

    You will sell a bucket load of these – and plus I too want to get better with more surface mount practice, and this seems like a super way to learn!

  • the firmware of the week feature sounds very good to me!

  • I'm suggesting Midi Clock Tester that measures frequency of the incoming midi clock messages and displays average BPM count and standard deviation.

    I have one on the breadboard and it's really useful tool for tuning up computers running software midi sequencers and sorting out all sorts of midi instability problems. Mine uses four 7 segment LEDs, however I can imagine it being implemented with just one 7 segment LED.

    If a Toy Box would have 8x1 LCD, a couple of push buttons and maybe a rotary, it would be a clear winner: people will be writing their own firmware for it using Avril. I'll immediately order 4 just to practice SMD soldering and implement Midi Clock Tester and maybe Midi Event Generator.
  • I’m still inexperienced when it comes to routing SMT boards, and I haven’t really tested how the 3.3V MIDI thing will work (the small, backlit LCD I found from a reliable source is 3.3V, so everything on this board will be at 3.3V to avoid level translation).

  • Looks great!

    Any chance you can add an optional LED and a pull up resistor?
  • I want one .... öhm... 5.
  • @kvitekp: Where do you want the pull-up resistor? There are already two LEDs (G and R) below the MIDI in and out.

  • @pichenettes: please disregard, I missed those two LEDs below MIDI ports.

    MIDI at 3.3V: I've been running an Atmega32 based board with MIDI IN and OUT (GorF sequencer) at 2.7V for quite some time with the 5V bench power supply that resulted in 2.7V after LM7805 with no problems (besides slightly dim LEDs) using a bunch of different MIDI devices, both old and a new, on input and output. So 3.3V should be fine.

    What is your provision for connecting serial debugging terminal like FTDI cable?
  • There is only one UART on the ATMega168/328, so you have to choose between debugging and MIDI out. The OUT pads at the left and right of the board are connected to the UART TX pin, so you can connect your FTDI cable here. BTW, those pads are here to daisy chain several units – in case you want to put several of them into the same case and build a controller.

  • Cool! Hopefully we could use software UART on a spare port.

    Do you think it makes sense to add four holes at the corners so this little gem could be stacked with daughter boards a'la Shruthi-1 ?
  • Yes, there might be 2 or 3 holes at some point, when I’ll have figured out the housing for this.

    There are 9 spare ports: PB4 (accessible through the MISO pin of the ISP programmer), and PC0..7 (which are exposed so that you can connect sensors / pots and use this as a basis for building a MIDI-enabled thingie).

  • cool, just seen this. some interesting sounding ideas :) Especially a very stable MIDI Clock source. This would however ideally have more than one midi out (maybe?)

    God only know how id get on with SMD stuff but worth a shot if not too much.

    Sounds like a good project.

  • Great ideas.

    One idea that has plagued me since hearing about it is the “pseudo-algorithmically generated” step-sequencer. Oliver, you mentioned this a long time ago, when first talking about the Shruthi. All it would need is a button/encoder combo, for input and selection.

    Maybe you have these preset patterns in memory and you can hybridize or randomize them, by using the encoder to control the amount of the effect.
    Euclidean pattern generator would be close enough, though!

  • Added to the TODO list.

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