Category Archive: arduino

Subcategories: No categories

The effects processor I’m not building this month.

In my last post, I mentioned that I had a good idea shortly after declaring “no new projects for a little while.”

Doesn’t mean I can’t talk about it. And hey, maybe one of you readers will take up the torch and design the schematic, PCB and/or firmware for me, so that when I clear my project backlog, it’s ready to go!

I’ve gotten really interested in the Spin Semiconductor FV-1 effects processor IC. It’s got built-in ADCs and DACs (so it’s a one-chip solution unlike some others), and if I’m reading the information on the web correctly, they almost seem to be encouraging the equivalent of a ‘clock bend’. I’m sort of curious as to how slowly it can be clocked – their examples don’t go below 20 kHz, but I wonder how lo-fi one could get it. I should ask on the messageboard…

Here’s kind of the feature set I was imagining:

  • Switchable clock rate, between a fixed clock (at the suggested 32768 kHz or maybe better if you’re some kind of audiophile type), and the variable schmitt trigger clock outlined on the website, possibly tweaked to go lower if that’s technically feasible. Hot-switching between modes need not be required- I’d be cool with having to power-cycle it when changing clock mode from fixed to variable.
  • The FV-1 on its own supports the use of a Serial EEPROM for additional effects programs. Change this to some kind of bank-switching multiplexing arrangement to allow multiple Serial EEPROMs to be used.
  • Front panel/microcontroller. Use something like an ATMega168 (preferably with Arduino-type bootloader so upgrades to the firmware are easy, and include the headers for an FTDI programming cable!)  to control a 2×20 character LCD panel, and set the bank/program numbers. If you need more inputs, outputs or memory, feel free to use something bigger (ATMega644p in a Sanguino arrangement, etc.) Don’t worry about program names for the external banks. “BANK 3, PROGRAM 4″ is fine. Feel free to use whatever menu navigating mechanism you want (buttons, pots, etc.)
  • Additional features would be up to you. If you can add a simple mechanism for uploading new effects programs to the Serial EEPROMs (especially from Mac OS X), that would win, but I’ll live with the possibility of using a separate EEPROM writer and removing/inserting the ICs.

A starting point for looking into might be this one, but I think I want mine in a 1U rack form factor – I’ve got too many desktop doodads already, and it’s time to get vertical. This post also has some tantalizing ideas (Arduino as EEPROM writer! Write your DSP code  in Java!) but they’re not released yet.

So, there’s my idea.

More hack potential than previously thought…

A couple of weeks ago, I picked up one of these on a whim – it’s got an LCD display, a little keyboard, a card reader, and other crazy things – why not? I wasn’t terribly interested in having to deal with 8051/8031 series programming, however.

A couple of Google searches later, I’m happy to discover that none other than the Atmel ATMega32 (as well as a bunch of other Atmel microcontrollers) is more-or-less pin-compatible with the 8051.

And hey, various and sundry Atmel microcontrollers like the ATMega32 have some compatibility with the Arduino environment I’m familiar with.

Now, obviously, this is all still a bit of a thought experiment at this point – I would need to get an ATMega32 (I’ve had AVRSyn on my to-do list for a while now, so I was going to get one eventually) and some sort of programmer to go further, but it seems like this crazy plan will work with some hacking involved (i.e. the clock crystal would likely have to be replaced too – I’ll have to look at the schematics).

Time for a mixdown

ready for mixdown

I’ve got things more or less ready for mixdown on this thing I’ve been poking at for the last few months. Here’s a little excerpt of a track: teaser1.mp3

What’s all that you say? Well, going from left-to-right on the 4-track: track 1 is  shortwave radio, track 2 is my cigarbox Lunetta, track 3 is Sound Lab, and track 4 is percussion (ADV-Bass for bass drum, Realistic MG-1 for snare, and the  Sound Lab is doing the hi-hats. BD & snare triggered by Arduino Sequencer, and Sound Lab triggered by its own S&H and not really synced)

Not bad for a pile of gear I either built or repaired myself, eh?

Tagged ,

The Lowest-Fi Digital Delay

A little while ago, I built my own Lo-fi Arduino Guitar Pedal. I’m even using a similar enclosure – work tossed out a couple of thinwire->twisted pair converters that I snapped up. I think the only major deviation is that mine only has one output at present- I could add a second later, though.

I got to thinking last week that a digital delay would be an interesting idea – I had no notion that this would compete with anything in the quality department- a very short, crunchy delay – I just wanted to try it out.

So I wrote a little program and originally used an array of 512 values, and cycled through them, while recording point i, and playing point (i+1) (with edge checks and things like that, of course)

It turned out that 512 shorts of storage must have overflowed available program memory and caused general non-functionality. Changed the delay to 256 shorts. That at least got me up and running.

And it gave me about a second of delay time – kind of unexpected (that makes the sample rate, what, a few hundred Hertz?). It also doesn’t give a very accurate representation of the input. A test went something like this: snare (pause) krrrzzk.

audio: ArduinoDDL1.mp3

Once I commented out the #define DEBUG 1 line, it seems a lot happier ;-) There isn’t very much delay time, and it still gets really weird on occasion, but it does kind of do something to the input.

Here’s an example of it, with adjustments to the amount of delay and effect mix: ArduinoDDL2.mp3 – note that it gets loud and obnoxious in places.

Maybe better than the crappy plate reverb of a few weeks ago? Really, hotrodding my Realistic would be the best way to go for the all-DIY album. Probably not enough time for that, though – I’d really like to get it done soon.

If you’ve built a Lo-fi Arduino Guitar Pedal, get the code here: ArduinoDDL.zip. Knob A controls the delay time, and Knob B, when set to zero, should flush the audio buffer and blink the blue light while it’s doing it. Or it’ll just do weird stuff. YMMV – mine certainly does.

Tagged , ,

a cold wave demo on a cold day

Here’s a little something from the whatever it is that I’m working on: thingdemo.mp3

Bass Drum: ADV-Bass

Bassline: Sound Lab Minisynth

(both controlled by the Arduino Sequencer in Drum Mode)

FM-y noises: Arduino Pocket Piano

The mix really isn’t properly done. I just wanted to get something out there. Have fun!

Tagged , ,