Welcome! About this forum, microcontrollers, & DSP

[aron]

We take a bold new step with this forum which will talk about using digital circuits.

[Peter Snowberg]

I would like to point out that with this bold step, we're stepping into TWO new worlds at once.

World 1: Microcontrollers

Microcontrollers are computers on a chip, usually with everything needed to make a fully functioning project except the switched, pots, and LEDs to interact with the user, and the oscillator that drives the whole process. Add these parts and you have the "brain" of almost every electronic device that isn't a personal computer. Microcontrollers (uC for short) are wonderful for doing basic functions like switching signals, and controlling parameters. They run anywhere from hundreds of thousands to millions of instructions per second and they're not really able to work with audio directly, but they can do wonders for controlling other devices or acting as building blocks.

Typical examples of microcontroller applications are the running remote controls, watches, microwave ovens, fuel injection systems in your car, the tuner in your digital stereo, the keyboard and mouse on your PC, every device attached to USB, hard drives, sprinkler timers, heating and cooling systems, MP3 players, alarm clocks, cellphones, home network routers, and traffic lights. I've heard it said that in 2004, greater than 95% of the computers in use were microcontrollers.

World 2: DSP or Digital Signal Processing

DSP is the art of processing a signal using nothing but math. The chips that do this are called DSPs, or Digital Signal Processors. These are high speed processors that usually process tens of millions to hundreds of millions, or even billions of instructions per second. They're not as good as uCs for watching the switches and pots on a control panel, but they chew on audio all day long. The thing that makes DSPs unique from most other processors is the MAC instruction which stands for Multiply-ACcumulate. This instruction is a multiplication followed by an addition to the result of the multiplication. believe it or not, the most complex digital audio effects come down multiplication and addition. The numbers that get used in these programs are the same numbers used to calculated component values in the analog world. One big advantage of DSP is that you can emulate circuits that would be difficult to build in the analog world, and then you can change them in radical ways just by loading new software.



Volumes have been written and published on these two fields already. We're going to repeat some of that info here, but with the twist that it's all going into DIY stompboxes. Please remember that digital is just another tool we can use in different ways. Lots of early digital that was low quality gave digital a very bad wrap that it didn't deserve. You can create poor quality designs with analog or with digital, we just tend to refer to the weaknesses of analog as "mojo'.


I would like to give special thanks to R.G. Keen, "Troubled Tom" Pollock, and Dan Green for providing the push to bring digital into our DIY forum world.

Of course, the ultra-special thanks goes to Aron Nelson for gathering us all together to share, learn, be inspired by, and enjoy the sonic landscapes that we can create with the tools that electronics provides us.


Let's get to it!

[Peter Snowberg]

A word to anyone planning to sell pedals with microcontrollers or DSPs in them (or BBDs):

Please read this thread:
http://www.diystompboxes.com/smfforum/index.php?topic=42399.0

Big Thanks to Jack Orman for this info!

[8ravo4lpha7ango]

Maybe slightly off topic but may I draw your attention to a post I made on this thread http://www.diystompboxes.com/smfforum/index.php?topic=56980.0, it's an idea about integrating a nord micromodular into a more stomp friendly package. You can pick them up for between £75-150 secondhand which in my mind is a total bargain. I know that many people dislike digital effects but there is no reason why you cant combine it with standard analogue boxes and use it mainly for time based effects. I would be really interested to see what some of the knowledgable people on the forum could do with something like this. I am sure others are doing this as well so I would be interseted to hear your thoughts. Also if processing guitar sounds in this way takes off I think it would be nice to have an area to trade patches. It's still a DIY stompbox in a way.