[sdiy] Polyphonic keyboard scanner

[cheater cheater]

The biggest reason to learn programming is because programming is fun :^)

On Sun, Aug 2, 2009 at 10:38 AM, Bruce Duncan<modcan at sympatico.ca> wrote:
> I bought that book and found it less than helpful.
> It assumes a far greater understanding of the topic than you will have as a
> beginner.
> Books never seem to be much good for this kind of thing as they always seem
> to be focused on quantity of information over clarity.
> Also they are out of date by the time they are published.
>
> There are simple examples available from Microchips web site and all you
> really need to get going
> is a template for your chosen processor and the family reference manual.
> Download the latest MPLAB software and purchase an ICD2 clone from Sparkfun
> or similar.
> Or better yet get the real thing from MCHP. You won't regret it later on.
> Then just start working through basic pin toggling and simple logic
> experiments till you get the hang
> of Assembly and instruction set. The Piclist
> http://www.piclist.com/techref/piclist/index.htm
> has tons of examples for earlier 16 and 18 series devices and is a treasure
> trove of clever
> methods to debounce switches and perform math without hardware multipliers.
> Take a look at some of Tom Wiltshires PIC projects. First rate synth related
> stuff for 8 bit PICs.
> You will get a good feel for setting configuration bits and assembly program
> flow from looking at these examples.
>
> Once you feel comfortable with the basics get some 16bit dsPIC30F samples
> and then you will be cooking
> as they have better facility for math, better ADCs, more RAM and faster
> clock speeds. Also the instruction set
> is far more efficient IMHO and easier to use. The 33F series are super cool
> but a major step up
> in complexity and non-C language examples are hard to find. Most of what
> applies on the 30F series does apply to the 33F though.
> The 32bit PICs are a totally different beast and so far seem unsuitable for
> synth use. Too early to say.
> It is a terrific learning experience once you get going although it can be a
> bit of a struggle at first.
> You will be amazed at what is possible though and it will consume you
> entirely for weeks at a time if you let it.
> I don't consider myself to be a programming expert by any stretch but I know
> a hell of a lot more than I did when I started
> and with the continued improvements in microcontrollers and availability it
> is difficult to ignore the benefits they offer
> in synth related design. Analogue or otherwise..
>
> Bruce
>
>
>> Thanks to all for the replies.  I am very interested in looking at the
>> Oberheim OB-Xa schematic.  Any hints where I might find it?
>>
>> Also, I bit the bullet and bought a book on microcontrollers today (at the
>> brilliant Powell's Technical Bookstore in downtown Portland, OR -- if
>> you've
>> never been, and you find yourself in the area, you really must check it
>> out!).  The book is "Programming and Customizing PICmicro
>> Microcontrollers"
>> by Myke Predko.  It's nearly 1200 pages, and it came with a PCB in an
>> envelope behind the front cover for building a PIC programmer (how cool is
>> that?!? -- I've never bought a book with a PCB in it before!).  Get this:
>> it
>> was only $22!  And, the project on page 922 is a switch matrix key
>> interface!
>>
>> > I cloned and upgraded the Tim Orr ETI Polysynth's polyphonic controller.
>> >
>> >  > http://rubidium.dyndns.org/cag/pdf/etipoly.pdf
>> >
>> > There are some mistakes in the poly assigner schematic. I have all the
>> > errors noted down somewhere - as well as a detailed section by section
>> > break down of what is actually going on. I may try and dig it out if I
>> > can find it.
>> >
>> > Other things to note: Cyclic assignment, like the OB-Xa, with optional
>> > note stealing and switchable total voice number, 1, 2, 4 or 8. Unusual
>> > +/-5V buss bar on the keyboard. Linear glide with OTA control.
>>
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