|Build Log| - DIY midi gamepad controller

[DjNecro]

...you get Repeated Joystick Button Presses based on the direction you turn the switch. Opens up all kinds of possibilities doesn't it."

found here

looks like these guys have the same problems has we have...

From my understanding of the datasheet, the switches are only 'on during changeover' (quoted from the ds)... I read that as CW switch will be on only when turned from CCW to CW and vice versa... So it would work as follows (pulses from switch are in parenthesis):

I am turning the knob CCW (no pulse)
I then turn the knob CW (CW switch pulses once)
I keep turning CW (no pulse)
I turn the knob CCW (CCW switch pulses once)
I keep turning CCW (no pulse)

I may be mis-understanding the datasheet though, I would research more about them before buying a ton of them... I didn't even know such a device existed and if it works like you say, that would be amazing. Dealing with grey code encoders can be a bit of a PITA....

[fbonito]

look here

"An Alternative to a Rotary Encoder

There is a special switch that makes a sequence of closures on one set of contacts when turned clockwise, but not counter-clockwise. It makes a sequence of closures on another set of contacts when turned counter-clockwise.

These switches can be wired to a keyboard encoder or a hacked keyboard.

Versions of this switch are made by Knitter-Switch, by Alps Electric Co, Ltd., and by Alpha/Xicon. Knitter-Switch calls the item a "rotary pulse switch" (model MRP1-20). Alps calls theirs a "pulse/rotation sensor" (model number SRBM1L). Elfa carries Alps products. Alpha/Xicon calls their switch a "pulse switch". Mouser carries it. Look for part number 105-SR10030-PS."

http://www.alps.com/products/WebObjects/catalog.woa/E/PDF/Switch/Rotary/SRBM/SRBM.PDF

what do you think?

[fullenglishpint]

only 20 pulses per rotation, lower resolution than an encoder.

[fbonito]

is 20 pulses not enought?

have a look here http://www.viperpits.org/smf/index.php?topic=5239.0

i only need one of these for my project, the problem is that i can find it for 5€ but the shipping is 25€... not very good...

[MiL0]

20 pulses per rotation would be sufficient for track scrolling in the playlist view?


by my (poor) maths, I calculate that a CC midi controller would be increased or decreased by just over 6 for every 'pulse' of the encoder... would make a filter or eq feel pretty 'steppy' I'd imagine? Or, if one pulse equalled just one increment/decrease of CC data then it'd take just over 6 turns to get a full 127 of midi CC data...

[fbonito]

whell the ideia is to have only one rotary to go up and down, up and down scrolling, change presents, etc.

i imagine like being something similar to having to buttons, one up and one down, pressing as much times as i want...

does this make sense?

[DjNecro]

Ahhhh very very nice... I like that very much...

Regarding the pulse count... Remember that you're not sending position data, only direction data. You will send a single pulse for each step of the rotation. You can adjust the sensitivity of the control directly within traktor...

Now that I am thinking of it, you're planning on using this as an HID controller, so my statement above may not be exactly accurate in your case. I have a pair of 24 pulse encoders (using grey code) that i use for the pitch controls, using the sensitivity/acceleration inside traktor lets me control the pitch by .01% per pulse (pressing the encoder and turn gives you a .75-1% change)

[fbonito]

yes,

i just want to turn to one direction and have consecutive single pulses in one terminal, and turn in the other direction and have single pulses in another terminal...

[DjNecro]

That sounds very possible... My (normal grey code) encoder sends 0x7F for CW and 0x01 for CCW using MIDI (that's in hex, so 127/1 in decimal), if you are using HID you would send say 'L' for CCW and 'R' for CW.. The only downside is you lose the ability to control the sensitivity of the encoder due to it essentially being a keyboard.

[fbonito]

that's ok,

it's just one rotary, i then will have more analog pots.

good news, i've made the order for the rotary for less than 2$ from a company in the neederlands...

:-D