Muff's Modules & More

Tombola

A couple of people asked for some details on the Midi beat clock mentioned here

I built it using a proto kit and faceplate from http://synovatron.blogspot.com/ - had to drill out a few of the holes, but it's much easier than starting from scratch.

The circuit is super simple, and I haven't drawn out a proper schematic. There are 4 parts to it

ARDUINO: The supporting circuitry for the Atmega 328 chip is surprisingly straightforward- +5v power, ground, one resistor, one 16mhz crystal, two caps, a press switch and some header. I used this Boarduino schematic from LadyAda.

I bought an ATmega with the bootloader already in place. You then need an FTDI cable to program it - it works exactly like a normal arduino. You can power the module over USB while programming it - presumably not a good idea to attach USB and the power ribbon at the same time! There is supposed to be a way to use a normal arduino board as an FTDI cable, I didn't try that.

Once it's in place, it's easy to attach a couple of pots (+5 and GND on each side, the centre lug going to an analog input), a switch (rigged as a voltage divider giving three levels on an analog input) and a pulse input (a 3.5mm jack going straight into an analog input with a pull down resistor to filter out noise when it's not connected)

OUTPUT: You can clock a sequencer, trigger a Maths or ping a Qmmg using a digital pulse straight from the digital out of an arduino. So the outputs are just a digital pin connected to a 3.5mm socket, with an LED going to ground through a resistor. I'm sure it would be better to buffer everything properly, but I didn't.

POWER: You can pull 5v from your case. Buy the little doepfer/makenoise adaptor, or make one from a 7805 regulator, a heat sink, perfboard, header and a capacitor.

MIDI: The Midi In schematic is in this thread. I think the original handrawn schematic has the midi pins the wrong way round. I certainly had to try a couple of times to get it working. I used a CNY14-4 optocoupler.

Midi goes into the serial RX pin on the Arduino. You can't have Midi playing while you upload code to the board. I had some weirdness with my board and my FTDI cable (I needed a 5v version, had a 3.3v version) that meant I had to halve the baud rate. YMMV.

Untitled by Tom.Whitwell, on Flickr

CODE:

I'm not going to post all my code here because it's too gruesome. If you want it, I'll happily send it to you.

It's all built on the sample code here at Little Scale. The arduino listens for a clock. When it hears a clock pulse, it triggers a subroutine.

The clock divider itself is simple: Set a counter running when the clock starts - midi clock comes 24 times per quarter note - then divide down using modulus

Luka · Posted: Thu Apr 14, 2011 9:50 pm Post subject:

nice work

widdly · Posted: Thu Apr 14, 2011 11:21 pm Post subject:

Cool. It would be handy if it captured FA on the midi and output a start trigger. That way you could reset your sequencer on midi start.

limpmeat · Posted: Thu Apr 14, 2011 11:39 pm Post subject:

good idea

falafelbiels · Posted: Fri Apr 15, 2011 5:26 am Post subject:

I am keeping an eye on this...

Tombola · Posted: Fri Apr 15, 2011 7:14 am Post subject:

wetterberg · Posted: Fri Apr 15, 2011 2:24 pm Post subject:

nice. Thanks for the update. Now, I'm not all that savvy on the tech here; what would happen if you accidentally sent *in* a 12v pulse to an output? You'd fry the ATmega, wouldn't you?

nickciontea · Posted: Fri Apr 15, 2011 2:27 pm Post subject:

i've given my analog ins severely wrong voltage and my original arduino is still pounding away..

seems to me they can take some abuse. Dead Banana

plus you can always use a diode

Tombola · Posted: Fri Apr 15, 2011 4:57 pm Post subject:

falafelbiels · Posted: Sun Apr 17, 2011 10:43 am Post subject:

falafelbiels · Posted: Sun May 01, 2011 11:35 am Post subject:

Tombola · Posted: Tue May 03, 2011 2:34 pm Post subject:

falafelbiels · Posted: Tue May 03, 2011 4:07 pm Post subject:

OK, I have plenty excuses not to do this right now, but I will PM you when I have the time, OK?

5 minute job, I really must learn to do this stuff...

knob_alchemist · Posted: Fri Feb 17, 2012 4:01 am Post subject:

Very interesting project, I have an unused Arduino and I will try to do this instead to buy an A-160.....Is possibile to use also the 6 PWM outputs as a 6 sub-divided clock signal outputs??

Tombola · Posted: Fri Feb 17, 2012 5:40 am Post subject:

Yes, all outputs are digital, would work for pulses

sicpaul · Posted: Fri Feb 17, 2012 6:23 am Post subject:

Cool project! love

I wish I was able to understand how to put all these fragments together to get a full schematic by now ... the time will come ... one day

FA (Start) will be a great feature, indeed.

And maybe the possibility to have a switch choosing CV-Clock instead of MIDI to increase the flexibility.

Again: great work, Tom

best regards
Paul

sanders · Posted: Sun Feb 19, 2012 6:24 am Post subject:

I just bought an Arduino from Radio Shack with the intention to build some kind of MiDI to pulse/trigger for triggering some korg and rhythm ace drum boards (most of the drum sounds seem to trigger on 4 or 5v, some seem to want -4v or so). I don't have code or a schematic, but I figured someone must have done something like this already.

But I haven't found anything after immediate searches. Can anyone point me to a drum trigger/ pules/ gate output project?

krz · Posted: Sun Feb 19, 2012 9:06 pm Post subject:

[quote="sanders"]But I haven't found anything after immediate searches. Can anyone point me to a drum trigger/ pules/ gate output project?[/quote]

just on the off chance u haven't searched here...

http://www.arduino.cc/playground/Main/MIDILibrary

knob_alchemist · Posted: Mon Feb 20, 2012 1:45 pm Post subject:

Hey what do you think, is possible a simple clock divider like this using your project/code? simple put in an LFO to one analog input and the 6 PWM ouputs give the divided clock...What do you think?

EMwhite · Posted: Mon Feb 20, 2012 10:34 pm Post subject:

I never messed with the *duino stuff but had a question.

I'm after a small / inexpensive or DIY device with a 3 digit LED display for BPM (tempo), a pot to change (from 40..240 possibly), that could output SYNC24 and have a clock divider. Is the platform above a good starting point?

Ideally, I'd like it to ALSO send Midi clock and have not only Run/Stop button, but also a positioning for Reset and Record that simply sends a predefined MMC command.

Any help in understanding how easy or difficult would be welcome. I was interested in the TeenageEngineering kit that they just released but zero details on the API and aside from not yet being available, it's $299 USD which is a bit much.

Thank you.