Random switch triggering

[ignotus]

Hi,

I have an old handmade MD board I don't use and decided to re-purpose it to make a guitar pedal board to use with Amplitube. A bit overkill I know, but it's better than leaving it to collect dust... So I'm just using the rim inputs as switches with the function set to program change. I'm still at the testing phase before I put it in an enclosure, and what's driving me up the wall is that no matter what threshold and gain settings I try, once in a while I'll get a random trigger, as if a switch were closed (it's not), causing Amplitube to switch presets.

So my question is - why might this be happening, and what can I do to remedy it? I thought the wires might be picking up noise, but it continues to happen without them. Are there combinations of settings that can make it less probable? I've spent the last couple of evenings trying different settings and some make it worse, some better... but the problem persists. Here's a screenshot of my settings to see if someone can shed some light - I'm using the same for all the switches.

Screenshot_MD.jpg

[dmitri]

How often does it do the random switching?

[ignotus]

Once every few seconds on each input. Today I attached cables for all the switches I intend to use (8) and the problem is worse - the switching is almost constant. I switched the inputs from "program change" to "normal" to see what happens in the midi log, and the strange thing is that all inputs are sending a c-1 (note 24) aftertouch message when they are set from 0 to 8. I'll attach a screenshot and my full config to see if you can spot anything.

Screenshot_MD2.jpg

[ignotus]

It's somehow related to the bow/head inputs. If I disable all inputs and just enable one bow/head input, it starts sending c-1 aftertouch messages.

[dmitri]

You set Gain to 0 on the Edge. It will make the Threshold range for switch make/break detection very narrow.
Set Gain to 8 and re-adjust the Threshold on the Edge.

[ignotus]

I tried that and the bizarre thing is that the threshold range where the switch works stays pretty much the same (6-31), and if I raise gain and threshold the problem gets worse. I also tried using other inputs in case a muxer was misbehaving or something, but the problem is the same, only the aftertouch messages change to other notes that I haven't set anywhere either...

[dmitri]

With Gain 8 what are the minimal and maximum Threshold levels when the edge switch still works?
Seet Gain to 8 and post a screenshot of settings with what you set the Threshold to.

[ignotus]

With gain at 8 the switch works with threshold from 7 to 32. Here's the screenshot.

Screenshot_MD3.jpg

And the midi log with a different midi channel assigned to each input - it's the only way to tell which inputs are triggering, and it's nearly all of them.

midi log.png

[ignotus]

It gets better... I assigned midi channels 1 - 10 to rim inputs and 11 - 16 to bow inputs. Why on earth are bow inputs sending aftertouch messages?

midi log_2.png

[dmitri]

The Aftertouch message is sent for a last triggered zone between Bow and Edge, not for the Edge zone only. If neither Bow nor Edge triggered after power up, then the last triggered Note (and channel) may be any random Note number (more likely Note 0).
Is anybody else with Atmega644/1284 having the same problem with the switch zone randomly triggering aftertouch?