One more MegaDrum firmware to test

[rockdude]

...and requires a precision rectifier (1 or 2 opamps per channel depending on power source) since the first half wave they produce is negative

The first half will be positive if we change polarization? I guess yes... The only tihing is to change wires from piezo sensor.
BR
Michal

So it could be used with a current MegaDrum build?

[zaklinacz]

This is the question to Dmitri, as I'm not sure if my thinking is good.
BR
Michal

[rockdude]

This is the question to Dmitri, as I'm not sure if my thinking is good.
BR
Michal

ok, and it probably has to be tested with Atmega too.

[Ken Forgettable]

Isn't sampling a full wave it's going to take a lot of time?

If you are doing this to calculate the head frequency why not (quarter_ wave << 2) - effective for high sample rates.

It might be that a tangent vector on the above can be used to isolate the impulse from the resonant frequencies. That's were I am right now

If anyone would can start a new thread for their signal conditioning hardware maybe that could get really informative...

[dmitri]

Ken, don't make it look harder than it is. As I said it already works fine on ST32M with Roland and Drumtec pads with a full wave precision rectifier. The rectifier is only needed because the first half wave on these pads is negative. The same algorithm may work on Atmega but I have not tested it yet. If it doesn't, the positional sensing can be limited to 1 or 2 pads to let Atmega cope. No need for a new thread.

[rockdude]

Ken, don't make it look harder than it is. As I said it already works fine on ST32M with Roland and Drumtec pads with a full wave precision rectifier. The rectifier is only needed because the first half wave on these pads is negative. The same algorithm may work on Atmega but I have not tested it yet. If it doesn't, the positional sensing can be limited to 1 or 2 pads to let Atmega cope. No need for a new thread.

Ok, keep up the good work Dmitri and please keep us updated whenever there's something new to speak of. I'll help testing this if you need any test results from different pads.

[mackanov]

Let me see if I understood. With pads that generate a positive first half-wave there would be no need to add any component for it to work using ATMEGA? Couldn't you invert the wave on a per-pad basis by using an adapter, such as inverting the wires on the jack? Or, if not, couldn't you use the precision rectifier as a separate device (perhaps drawing power from an external source) between the pad and MegaDrum? It might be easier and cheaper to add components to the pad instead of adding it to MegaDrum, if it can be done, right? Or am I going too far?

[dmitri]

You are right. But many drummers out there were scared of adding a simple external voltage divider, let alone something with opamps.

[rockdude]

You are right. But many drummers out there were scared of adding a simple external voltage divider, let alone something with opamps.

Well, since most people (and sample libraries so far) only use/allow positional sensing on the snare it would only be necessary to add it for one pad. I'm really stoked about this. It would be übercool if MegaDrum did support a positional sensing feature!

[Ken Forgettable]

Ken, don't make it look harder than it is.

Well backward compatibility has always been a watch word in software development, but I am still of the opinion that DEC, IBM and M$ ate themselves largely due to the bias towards this as a marketing idea; and I still wonder why anyone would pay £1000s to play a weedy two position sensing snare

(Get this: http://en.wikipedia.org/wiki/The_Soul_of_a_New_Machine).

I asked before if the STM32 Megadrum will still be open hardware...

I got the same precision except for very light hits <snip> so I'm working on version which would require only 2 opamps <snip> No need for a new thread.

... because there are loads of designs already out there (and thousands of op amps) that look fine on paper but when constructed, the reality is somewhat different...


'Yet if cattle or horses or lions had hands and could draw,
And could sculpt like men, then the horses would draw their gods
Like horses, and cattle like cattle; and each they would shape
Bodies of gods in the likeness, each kind, of their own.'
Xenophanes of Colophon.