Muff's Modules & More

ZoeB · Posted: Sat May 12, 2012 10:34 am Post subject: Homebrew step sequencer

Hi everyone!

So my partner and I are making a homebrew step sequencer. She's making most of the hardware, and I'm making most of the software. It should hopefully be vaguely similar to the TB-303 and MC-202's sequencers, in as much as it has that very specific kind of portamento.

The source code is split up into a library class which can be used by a bunch of different applications, so eventually we can build various different hardware devices without having to rewrite all the code from scratch.

We're currently up to the stage where the prototype is ready for trying out. There's a Git repository at git://github.com/ZoeB/surf.git if anyone would like to give it a go. The whole project's open source, so anyone can dissect it, modify it, and use it in their own open source projects.

To try it out in Linux, OS X etc. try: "git clone git://github.com/ZoeB/surf.git; python3 surf/python/stepper_1_prototype.py" It's a bit awkward as I'm emulating a bunch of electronic components in a terminal window, but it does work, albeit not actually doing all that much.

I'll let you know when there's been some more progress, such as actually porting it all across to C++, copying it onto an Arduino board and hooking it up to a real synthesiser. So far, we only have some test code doing that, playing a preset acidline, but again, it does work as a proof of method.

Enjoy!

JRock · Posted: Sat May 12, 2012 11:20 am Post subject:

Awesome

Good to hear. Keep us posted.

bleeps · Posted: Sat May 12, 2012 12:00 pm Post subject:

Looking forward to seeing this progress w00t

iopop · Posted: Sat May 12, 2012 1:03 pm Post subject:

Whats the reasoning behind making a POC for python first? Fasster/easier prototyping?

Cloned, had a test run, gotta love ASCII interfaces. I suppose in the final device each mapped key will be mapped to a gpio on the Arduino? Or whatever a input might be called on that platform.

darenager · Posted: Sat May 12, 2012 1:11 pm Post subject:

Sounds cool! Will there be kits or finished versions available in the future?

frequencycentral · Posted: Sat May 12, 2012 2:08 pm Post subject:

This sounds exciting to me!

ringroad1 · Posted: Sat May 12, 2012 2:17 pm Post subject: hats off

nice

I've got the Python prototype working here, I like that it's editable on the fly. Interested to see how you will handle saving the pattern to storage, I had a go at writing a sort-of super CSQ-600 using an Arduino, and had to time the write to (super-slow) EEPROM carefully for fear of missing triggering the next step.

I had a look at the 202 and the 303 slide, the 202 looked a lot simpler, and a sounded pretty good, although I've not been able to compare the two in sound.

I like that you've got an extra CV output in there, being able to control filter cutoff is such fun.

One thing from the Sokkos x0xb0x firmware that is nice is pattern rotate if you can squeeze it in there somewhere...

Looking forward to seeing this working on the Arduino.

ZoeB · Posted: Sat May 12, 2012 6:09 pm Post subject:

Thanks everyone!

ZoeB · Posted: Sat May 12, 2012 6:11 pm Post subject:

[Accidental duplicate post deleted. Ahem.]

falafelbiels · Posted: Sat May 12, 2012 6:46 pm Post subject:

Color me interested.

w00t

ZoeB · Posted: Mon May 21, 2012 2:16 pm Post subject:

For future reference, I've moved this project to https://github.com/ZoeB/stepper , so if anyone can't find it, that's where it's gone. It's still the same project, I've just stripped out everything except for the sequencer so I can concentrate on that.

Well, that and I've made a bit more progress, adding eight trigger channels and starting to port it over to C...

Incidentally, it probably wouldn't be that difficult, from a firmware programming point of view, to make straight-up clones of the MC-8, MC-4, and the sequencer parts of the MC-202, TB-303, TR-606, TR-808 and TR-909... would anyone be interested in such things, and does anyone know if a replica that tries to match the original interface exactly is even legal?

Although for right now, I'm content making this multichannel sequencer with slide. :) I'm guessing I'm not the only person who wants to make some multitimbral acid? I might even throw one or two tempo synced LFOs in there while I'm at it... (A nice feature of plain clones is that they curb this kind of feature creep, hehe...)

Barcode · Posted: Mon May 21, 2012 2:59 pm Post subject:

Sounds very cool! I will be looking forward to updates!

roglok · Posted: Mon May 21, 2012 5:58 pm Post subject:

falafelbiels · Posted: Mon May 21, 2012 6:20 pm Post subject:

Cool, but I could do without a MC202 sequencer.
help

ZoeB · Posted: Mon May 21, 2012 6:32 pm Post subject:

ringstone · Posted: Mon May 21, 2012 7:26 pm Post subject:

This sequencer sounds very interesting ZoeB, I'm keen to see how it turns out. One feature that I would be looking for; is if it could synchronise externally to an analogue format, specifically Din Sync/Sync24. This still seems the best option for eliminating the timing issues that often occur using a MIDI based sync format - although I'm not saying that shouldn't be included as well!

Providing Sync24 allows the easy use of the sequencer live alongside the very popular Roland machines, as well as providing another rock-solid option to synchronise with DAWs and so forth (through the use of products such as Silent Way and Innerclock). Yet it's still rare to find modern sequencers/grooveboxes that have this facility.

Anyway, good luck with the project!

Cheers
Blair

ZoeB · Posted: Tue May 22, 2012 10:26 am Post subject:

roglok · Posted: Tue May 22, 2012 10:51 am Post subject:

ZoeB · Posted: Tue May 22, 2012 11:39 am Post subject:

roglok · Posted: Tue May 22, 2012 12:06 pm Post subject:

Paradigm X · Posted: Tue May 22, 2012 2:30 pm Post subject:

roglok · Posted: Tue May 22, 2012 2:52 pm Post subject:

I just downloaded your python script from github, but I'm having a hard time getting it to run properly on a mac.

I'm hopeless as a programmer and never tried python, so there's not much I can do about it. The script runs and the interface seems to work, but I'm getting the following bugs after 16 steps have played:

ringroad1 · Posted: Tue May 22, 2012 3:04 pm Post subject:

hey roglok, looks like you're using Python 2.6 - think it needs Python 3.

Got it working happily here on Snow Leopard with Python 3 installed via Homebrew.

roglok · Posted: Tue May 22, 2012 3:37 pm Post subject:

hey, thanks for the hint. unfortunately it doesn't help. i installed python 3 and even cloned the git repository via command line, but i'm getting this mess after the pattern has run once:

ZoeB · Posted: Tue May 22, 2012 4:21 pm Post subject:

Thanks for trying this out, everyone!

I believe the filename bug is something I broke earlier on, and fixed earlier today. I wasn't very consistent with where it was defined, basically. Try "git pull origin master" (or probably simply "git pull") to get the latest version, and see if that works.

And the other news: I've implemented Sync24 output (changeable to Sync48 by changing a constant in the code). You have to slow it down to about 1BPM to actually see it in action. I wasn't sure if the run/stop signal could go up at any time, or if it had to politely wait for the next time the clock pulse starts to go high. I decided to play it safe and opt for the latter, to ensure (hopefully!) rock solid timing.

I'm not very up on hardware, but I'm hoping it should be as easy to implement as finding two more digital outs to assign the sync output to, and soldering them up to the appropriate pins of a DIN socket. That may be wishful thinking on my part, though. :)

Let me think about the other features later on. Nina (my partner) has pointed out to me how simple Sync24 input should be, so I'll try that next, probably later this week.

roglok · Posted: Tue May 22, 2012 4:55 pm Post subject:

brilliant! thanks for the fixes. works like a charm now thumbs up

ZoeB · Posted: Tue May 22, 2012 5:01 pm Post subject:

OK, a Sync24 input question... if you get the run/stop gate at any time other than when one of the clock pulse triggers is starting, are you supposed to start playing immediately or wait for the next clock pulse? For the input, I really need to follow the existing conventions if I want this sequencer to sync up properly with other devices...

roglok · Posted: Tue May 22, 2012 5:08 pm Post subject:

ZoeB · Posted: Wed May 23, 2012 2:23 am Post subject:

ZoeB · Posted: Thu May 24, 2012 6:29 am Post subject:

roglok · Posted: Thu May 24, 2012 8:11 am Post subject:

sounds great, zoe! i'm on vacation so i can't check it out atm, but will do so when i get back...

ZoeB · Posted: Thu May 24, 2012 12:06 pm Post subject:

OK then... does anyone have any more information on Tape Sync (frequency shift keying), or any examples?

It sounds like you take the Sync24 / DIN Sync clock pulse, and whenever it's high you output a high frequency tone, and whenever it's low you output a low frequency tone. (Hey, I think I finally understand what modems and early home computers' tape recorders do! Modulating and demodulating, that makes sense...) It's still just square waves, so still a boolean value being sent to a simple digital output. Fine, I think I've got that working. Some sources (An Introduction to Tape/MIDI Sync and the MQX-32 and Sync or Swim?) claim the frequencies are 2400Hz and 1200Hz respectively, while others (MC-4 service notes, page 4) say "approximately" 2100 and 1300. I'm guessing Roland are more authoritative on the matter, if a little vague. I'm not sure how accurate this needs to be...

The main thing I'm not sure about, though, is how Tape Sync knows when to start and stop. This is a separate signal entirely in DIN Sync, whereas Tape Sync only uses one tape channel. The MC-8 owner's manual, pages 107 and 108, make mention of starting and stopping the track, with a bit of breathing room around it. Maybe it just says this to ensure you actually leave the clock pulse running long enough, but I'm hoping the equivalent of the run/stop signal gets passed along somehow. That would certainly seem to be the point of synchronisation, to not just match the speed but also the start time. Plus the manual says this modifies the carrier, insinuating either that it's further modified once you start playback, or that it wasn't modulated for an audible medium beforehand maybe (as in, maybe it sends out the raw Sync24 until the sequence is started)? Perhaps the sync signal is only output to the Sync24 or Tape Sync output in a mutually exclusive manner, so the manual's saying it's neither modulated nor output to tape at all until the song's started? Wouldn't that mean the slave device would only know the correct tempo after the song's already started? I have no idea...

So does anyone know how Tape Sync works, or better yet, have a .wav or .aif file example of it in action that I could dissect?

Thanks!

ringroad1 · Posted: Thu May 24, 2012 2:09 pm Post subject:

Couldn't work out where to put them so hopefully this'll do:

http://stevewoodward.posterous.com/roland-mc-4-sync-tones

It should be fairly obvious when I'm starting the sequencer.

darenager · Posted: Thu May 24, 2012 2:19 pm Post subject:

IIRC tape sync uses an initialising tone before anything starts to sync, then once the tone starts to modulate the slave will start. Just curious as to why you are thinking of implementing tape sync?

ZoeB · Posted: Thu May 24, 2012 3:08 pm Post subject:

bananeurysm · Posted: Thu May 24, 2012 3:21 pm Post subject:

Sweet! Looking forward to seeing this in action!

I sincerely hope you're not emulating the mc202 sequencer. I have a LOT of experience using it - and it only gets more and more frustrating the more you use it. I nominate it for worst internal sequencer ever. x0x on the otherhand is pretty nice!

ZoeB · Posted: Fri May 25, 2012 3:18 am Post subject:

ZoeB · Posted: Fri May 25, 2012 5:20 am Post subject:

Oh, I think I just properly worked out how the syncing works. I think it might be much simpler than I realised. What I've got Stepper currently doing is timing the distance between the last two pulses, and extrapolating the tempo from that, but that's no good if the song has to start before it's heard some pulses (so fine for DIN sync, but no good for tape sync). But now I'm thinking that's really overly complicating things, that the pulses aren't used to synchronise clocks among different machines after all; maybe the pulses are the clock, and the slave's internal clock gets disabled... maybe the slave machine just has to count pulses from the master, ignoring entirely how long they take to arrive, and if it's 24 pulses per quarter note, and the device only plays sixteenth notes, then it merely has to only increment a step once every six pulses. Hence, it doesn't need to be led in to get adjusted to the tempo, and the timing's bang on no matter how much you change the tempo half way through a song. It's a simple and elegant solution, great.

The only point at which it breaks down is if you need to update something more than 24 times per quarter note, such as portamento. Which further explains why the TB-303 implements sliding in hardware, not software (TB-303 service notes, page 5). So does that mean the TB-303's slide length, the time it takes to glide from one note to the next, isn't just independent of the pitch distance, but also independent of the tempo? And if that's the case, does anyone know how long it takes? I've currently got Stepper sliding only for the last half of a sixteenth note, so it takes a 32nd of a bar exactly. This seemed like an elegant solution until it had to be hardware and interface with other machines...

I guess I can refactor most of Stepper to work the simple way, but keep the portamento working the complex way. That way, the timing of everything except the portamento will be absolutely spot on always, and it will still be able to have tempo dictated portamento lengths, that may be slightly out if it's slaving to tape sync and there's portamento on the very first note. That's probably an acceptable trade off...

ringroad1 · Posted: Fri May 25, 2012 12:59 pm Post subject:

There's some discussion of the portamento/slide of the 303 and 202 over at ye olde hyperreal - seems like the 303 is constant time, as you suspect. Dunno how long it takes tho.

Robin Whittle wrote some good stuff on the triggering of the 303 slide which might come in handy:
http://www.firstpr.com.au/rwi/dfish/303-slide.html

Like I say, personally I'd take a look at the 202 slide circuit, but if you are trying to make several voices I can see why you'd be tempted to do it in software.

ZoeB · Posted: Fri May 25, 2012 1:27 pm Post subject:

bananeurysm · Posted: Fri May 25, 2012 2:38 pm Post subject:

Stoked!!!

ZoeB · Posted: Fri May 25, 2012 5:04 pm Post subject:

I've abandoned tape sync output. While I did get it working, I had to get into the world of microseconds instead of milliseconds, and I don't want to push this poor little device too far. Still, it works in software, so if you'd like to see it in action, just pull the latest version of the master branch and checkout the old, reverted commit, which I've kept for posterity.

(Of course, with a hardware square wave oscillator it would again be quite simple in the software realm, but then it'd be unnecessarily complex on the hardware side.)

I'll instead continue my curious trend of making Stepper really complicated to begin with, then incrementally simplifying it. :)

ZoeB · Posted: Sat May 26, 2012 1:48 pm Post subject:

Whew... I've completely rewritten a substantial part of everything, made it much more simple, made it DIN sync in compatible, and added a drum machine. It's now much more in line with how late seventies to early eighties digital sequencers work, with the clock and the actual sequencer being discrete things. Comments and suggestions are, of course, always welcome. :)

ZoeB · Posted: Sun May 27, 2012 5:06 am Post subject:

If you pull the latest version of Stepper ("git pull origin master" should do it), I've started to implement the Arduino C version of Stepper (/c/stepper_acid/stepper_acid.ino). There's not much there yet, but it's a start.

So far the Arduino just acts as a metronome, but behind the scenes, it's a 96 PPQN clock driving a 48 PPQN step sequencer, which makes the LED light up on rows 0, 4, 8 and 12. The reason for the different pulse rates is that this way, you could use this clock to drive another machine's step sequencer, or another machine's clock to drive this step sequencer, ignoring 1 in 2 pulses, or ignoring 3 in 4 pulses, or paying attention to both the start and end of each pulse, in order to make both the clock and the sequencer compatible with 24, 48 and 96 PPQN hardware. So I'm trying to ensure this will play well with others. :)

ZoeB · Posted: Sun May 27, 2012 1:05 pm Post subject:

It's a bit glitchy, but Stepper is now sending out signals! \o/

How it looks
How it sounds
How it works

The metronome-like clicking is probably an issue with sliding, which isn't surprising as I've completely revamped it, guessing at what might be good values, so hopefully I can fix that pretty soon.

Enjoy!

Paradigm X · Posted: Sun May 27, 2012 2:51 pm Post subject:

sounds amazing.

no idea wshatsover about the guthub thing but look forward to it being availble for lesser mortals.

thumbs up

ZoeB · Posted: Sun May 27, 2012 4:39 pm Post subject:

Bugs fixed! Raw and BBDed.

roglok · Posted: Tue May 29, 2012 3:52 pm Post subject:

sounds great, zoe!

matia · Posted: Wed May 30, 2012 6:18 am Post subject:

this is absolutely excellent! will there be provisions for song mode and autofill on a user defined count (like the 808/cr8000)?

very very interested in how this develops.

good luck!

ZoeB · Posted: Wed May 30, 2012 7:38 am Post subject:

ZoeB · Posted: Wed May 30, 2012 8:00 am Post subject:

OK, I've had a look at the intro / fill in section of the TR-808 manual... while there's no technical constraint stopping me from implementing that, I'd like to keep things simple for now, which means manually triggering intros and fill ins by selecting a different pattern to play next while the current one's still playing.

In stark contrast, in the behemoth I'd like to make later on, I would ideally make a screen where you can take each individual channel and program in the sequence of patterns you'd like. This would basically be like how it works in Amiga mod trackers, only instead of the pattern containing all the channels combined (which is how it worked in an earlier incarnation of Stepper's prototype tracker interface), I like the idea of being able to change the pattern of each channel independently, so you could introduce a new solo while the backing stays the same, or change the rhythm and bass parts while the arpeggio / broken chord parts stay the same. That kind of thing. (Especially so you can change chords while keeping the drums consistent.) But that's a while off yet!

ZoeB · Posted: Wed May 30, 2012 4:39 pm Post subject:

Nina insisted I play a famous acidline that we have reference material for, so we can tell how close we're getting with Stepper Acid. It needed to be something we knew the exact notation for, including slides, the pitches of all the rests, everything. Alas, the example I found isn't from a real TB-303, but at least it's an easily recognisable one!

As it doesn't use accent, I rewrote a few lines of code to repurpose that output for a kick drum. All I used was our Stepper Acid prototype, plus an A-111, A-132-3, A-140, A-103, A-183-3, BD88 and A-138. After I updated the firmware, no computer was involved, unless you count the Arduino's CPU.

The actual timbre sounds a bit odd to me, but that says a lot more about my patching (in)ability than my programming skills. :) That and I don't think you're really supposed to use an A-138 as a mixing desk...

The latest example of Stepper Acid in action

Enjoy!

dar303 · Posted: Thu May 31, 2012 6:39 am Post subject:

Try this!

ZoeB · Posted: Thu May 31, 2012 9:53 am Post subject:

Here you go! I'm not sure how accurate the transcription is, or how accurate my own translation of that into numbers is (as Stepper doesn't have an interface yet, I'm having to write the preset pattern by hand), and I'm not entirely sure what I should hook the accent up to (I hear it affects the filter resonance, which alas the A-103 has no CV input for)... so I'm not sure quite how authentic this sounds... but it definitely sounds good in its own right! :D

Acid Trax on Stepper Acid

matia · Posted: Thu May 31, 2012 1:32 pm Post subject:

ZoeB · Posted: Thu May 31, 2012 1:57 pm Post subject:

matia · Posted: Thu May 31, 2012 3:09 pm Post subject:

dar303 · Posted: Tue Jun 12, 2012 3:12 am Post subject:

Sounds great, good work! smile

( <--- thats an acid house smiley!)

ZoeB · Posted: Tue Jun 12, 2012 3:18 am Post subject:

Thanks! ^.^

ZoeB · Posted: Fri Aug 17, 2012 4:33 pm Post subject:

Hi again everyone!

So I've been working on a few other projects lately. This week I decided to resume work on Stepper, and so far I've finished implementing the serial interface over USB. This won't be in the final version as it slows the machine down whenever you do anything, but it's helping me test things before the hardware's fully built.

Basically, the finished versions should have buttons and an LCD. In lieu of those, the current version talks to a computer. It sends out a status report on its global settings and the current pattern, and gets back from the application on the computer any key presses. So there's virtual keys and a virtual screen instead of the real one, but when you use the application on your computer, it's controlling the real hardware device. The hardware sequencer is storing and playing the patterns, keeping track of which note you're on, updating it, copying and pasting patterns, and so far it all works except for switching patterns, because it doesn't have any storage space to read from or write to. But everything else works just fine.

So I'm making good progress!

Anyway, I just wanted to share my excitement at being able to program in acidlines on a hardware machine hooked up to my modular synth, even if it's currently by proxy. I'll keep you posted as things progress further.

ZoeB · Posted: Fri Aug 17, 2012 6:03 pm Post subject:

Oh, I forgot! The Arduino Uno has 1k of EEPROM built in. So I've just learnt how to read from and write to it. Pattern loading and saving now works, so Stepper Acid can currently store up to 15 acidlines, each up to 16 notes long.

ZoeB · Posted: Sun Aug 19, 2012 4:16 pm Post subject:

Here's a rough demo of where the sequencer's at so far:

mckenic · Posted: Sun Aug 19, 2012 5:48 pm Post subject:

Oh LORD! This is getting really exciting now!!!!

applause

ZoeB · Posted: Wed Aug 29, 2012 5:43 am Post subject:

lucid · Posted: Wed Aug 29, 2012 7:22 am Post subject:

eye will keep an I on this
eek!

citric acid · Posted: Wed Aug 29, 2012 8:08 am Post subject:

looks verry nice. i think your sequencer will help a lot of people to do a special sound with new an old gear. so thanks for your work an keep my fingers across that any thing will work.

will you release a diykit etc ? that will be verry cool.

thanks for this work and your treat we're not worthy

ZoeB · Posted: Wed Aug 29, 2012 8:36 am Post subject:

I've just increased the storage capacity. It can now store up to 30 patterns, not 15.

citric acid · Posted: Wed Aug 29, 2012 8:43 am Post subject:

nice. if you are looking for a company who take this in licence i can give you a contact to a friend. he has a company and look for new projects.

br,
cit

ZoeB · Posted: Wed Aug 29, 2012 8:57 am Post subject:

simfonik · Posted: Wed Aug 29, 2012 10:16 am Post subject:

Following along with great interest. Nice work!

falafelbiels · Posted: Wed Aug 29, 2012 3:22 pm Post subject:

This may have been mentioned before, I'm at work and can't really read the entire thread, but is straight clock possible? I wouldn't know what to do with din sync within the modular...

ZoeB · Posted: Wed Aug 29, 2012 3:34 pm Post subject:

mckenic · Posted: Wed Aug 29, 2012 3:44 pm Post subject:

A silly question please Zoe...

Does it have clock in & out?
Can it take Midi clock too, so you could use it as a midi->modular clock box? That would be WICKED!

Really interested to see where you go with this - If it stayed the same as the last video - I'd certainly want one thats for sure!

thumbs up

falafelbiels · Posted: Wed Aug 29, 2012 4:34 pm Post subject:

Actually what I mean is 1 clock pulse equals one step advancing. Din sync is somewhat specific to me.

ZoeB · Posted: Wed Aug 29, 2012 4:59 pm Post subject:

mckenic · Posted: Wed Aug 29, 2012 5:01 pm Post subject:

Thank you Zoe - bloody interesting stuff!

Hurry up!

applause

ringroad1 · Posted: Thu Aug 30, 2012 1:36 pm Post subject:

ZoeB · Posted: Thu Aug 30, 2012 2:09 pm Post subject:

ringroad1 · Posted: Thu Aug 30, 2012 2:46 pm Post subject:

The 101/606 combination is loads of fun, being able to rewrite the triggers live and change rhythm of the notes separately from the pitches is ace. Also love doing something like 7 triggers every bar over 8 notes in the sequencer, so the start point shifts every loop.

On the really short gate front, I just used the envelope on the attached synth to set a minimum length with a bit of release, but I guess someone could also set a minimum gate length in software.

But anyway, having said all that, totally agreed on limiting feature creep, you've got to stop somewhere or else it'll end up being able to make the tea.

Paradigm X · Posted: Mon Jan 14, 2013 10:28 am Post subject:

What news for the stepper?
thumbs up

ZoeB · Posted: Mon Jan 14, 2013 10:53 am Post subject:

Paradigm X · Posted: Mon Jan 14, 2013 12:21 pm Post subject:

Cool, let us know wink

Someone really needs to build a 606 type sequencer as well...

Cheers

falafelbiels · Posted: Tue Jan 15, 2013 6:39 pm Post subject:

ZoeB · Posted: Tue Apr 02, 2013 4:05 am Post subject:

I'm not allowed to give away details yet, even though I'm itching to, but a good amount of progress is being made now...

falafelbiels · Posted: Tue Apr 02, 2013 6:01 am Post subject:

citric acid · Posted: Sat Apr 27, 2013 2:08 pm Post subject:

looks nice. It's motherfucking bacon yo

ZoeB · Posted: Sat Apr 27, 2013 2:59 pm Post subject:

It sounds pretty good too now. :D Nina got the timing down to about 300 microseconds lag from DIN sync input to gate output. I've also added a few nice features...

citric acid · Posted: Sun Apr 28, 2013 2:36 am Post subject:

ABC · Posted: Sun Apr 28, 2013 4:30 am Post subject:

waiting with bated breath