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HGH
04-18-2007, 12:38 AM
Hello,

I'm relatively new to BS2s, and newer to forums, but have been working on a couple of projects using the stamp recently & have been a bit stumped. This forum seemed a good place to put it out there, so I thought I'd try. Please forgive me for any obvious questions, etc...

I'm building a drumpad with 10 fsr sensors to send midi notes with velocity. With simultaneous hits, timing's important. Originally, I originally tried to lessen hardware by using PULSIN, but there doesn't seem to be a quick way to scan 10 pins for pulses (it also seems to not be sensitive enough for this kind of sensor, though I'm not sure). I've checked out NV 94 & 95, and after some study (and learning), realize that velocity-sensing from each pad needs a different approach. I saw one of Jon William's posts and purchased several 8-channel ADC 0838 chips, and am now wondering if there's any code to reference or use as a starting point that converts multiple analog inputs to midi notes using ADC.

I've also seen recently that the SX is a quicker chip, but have already committed to several BS2's. I hope the bs2 is doable, anyway...

Thank you...
Howard

hitsware
04-18-2007, 08:57 AM
Do the drumpads send midi ?
Midi is a serial medium so there is a possibility of timing issues with too many events at once.
This is inherent in midi itself, though it can sound fine.

HGH
04-18-2007, 11:45 AM
Hi,

These drumpads are simple fsr sensors without midi. I've connected a 5V battery so when hit they'll pass a voltage spike to the bs2's pins proportional to the hit. I'm trying to code the BS2 to convert this voltage to a midi note on (and off) with velocity. I see what you mean about the serial nature of midi, so true simultanaeity(?) isn't possible. I don't think more than 2 or 3 hits will occur close together though and as they're simple messages hopefully midi won't be the bottleneck... In trying the conversion using pulsin, my concern was that the bs2 scanned fast enough catch all input immediately. But my software approach never quite worked. My next step is to try the adc chips.

Howard

hitsware
04-18-2007, 12:06 PM
Don't they make midi drumsets ! ?

Analog to midi is a·pain .......<|:^))




Post Edited By Moderator (Chris Savage (Parallax)) : 4/18/2007 7:51:42 PM GMT

HGH
04-19-2007, 12:41 PM
Cost is an issue. I have all the pads & pedals. I've plugged them into an Alesis d4 as simple triggers, but am moving toward midi because it's more universal... (map fsr pressure to pitch bend, use any drum machine, even a battery-operated one (only midi in)), and also because this project is one of a couple that will be needing analog-to-midi.

I've done some basic midi triggering based on the NV columns, so it seemed that analog-to-midi would be doable. Does the timing or velocity complicate it?

hitsware
04-19-2007, 07:49 PM
HGH said...
Cost is an issue. I have all the pads & pedals. I've plugged them into an Alesis d4 as simple triggers, but am moving toward midi because it's more universal... (map fsr pressure to pitch bend, use any drum machine, even a battery-operated one (only midi in)), and also because this project is one of a couple that will be needing analog-to-midi.

I've done some basic midi triggering based on the NV columns, so it seemed that analog-to-midi would be doable. Does the timing or velocity complicate it?
Obviously you've done more than I have in this area.
Seems like if you ran the "spikes" from the sensors through comparitors and then to the scanned pins,·that the width of the spike (proportional to velocity)would determine·how many 'highs' read. So the·pin# would be mapped to voice and note and # of high reads·to velocity? This should be faster than ADC .....
You might get some ideas here:

http://www.borg.com/~jglatt/
http://www.audiomulch.com/midipic/

Post Edited (hitsware) : 4/19/2007 12:27:00 PM GMT

HGH
04-19-2007, 10:20 PM
Wow... What "area"? Tinkering with stuff I bang, or knowing circuits & coding?

The DIY website you suggest is on point, and your suggestion sounds excellent, in a vague sort of way!

I thank you sincerely for a new learning curve...

Howard