9 replies to this topic

[monewwq1]

With Netduino, how can I connect a single wire such that I can switch whether or not the wire is going to ground? Would I use a transistor? The wire does not need any voltage connection- it is just a grounded/un-grounded wire depending on whether I "switch" it between grounded or un-grounded. The other end of the wire is not connected to anything. Thanks!

[monewwq1]

Just so you know what I need to do:

• Connect anti-static foam directly to the display of an iPad (the anti-static foam is the stuff that IC's are normally mounted on when shipped)
• Connect a wire from Ground to the anti-static foam
• Trigger the Ground connection on and off

This makes the Netduino "touch" the iPad touchscreen. I've already tested this simple scenario and it works, but I have to physically touch the wire to Ground and remove it. I need some way of doing this with Netduino programming.

I have an iPad drums application, and my current idea is to make an automatic drum sample controller with the Netduino;

• Connect anti-static foam to each drum kit point on the iPad display
• Connect separate Grounds for each wire
• Trigger these wires individually so I can press each drum-kit item separately (high-hats, cymbals, bass drum, etc.)
• Record and play back the drum sample on the Netduino, sort of like one of those pianos that plays automatically.

This would also allow me to trigger the drum kit with other materials by using pressure sensors. Ultimately, I could use regular drum sticks on other materials to play the electronic drum kit on the iPad.

The problem I'm solving with this: the iPad display is small, and obviously I cannot smack real wooden drum sticks directly onto the iPad display, so I have to use my fingers to play the drum kit, which is not true to a real drum set, and it is cumbersome.

This would open up the ability to create a small electronic drum kit that could be played with real drum sticks. All the sounds are already there on the iPad; I just need to implement the electronic connections to "touch" the iPad display.

What do you think? Dumb idea? Cool idea? Useless idea?

Has anyone done anything like this before? Any tips?

Thanks!

[Darrin]

Just so you know what I need to do:

• Connect anti-static foam directly to the display of an iPad (the anti-static foam is the stuff that IC's are normally mounted on when shipped)
• Connect a wire from Ground to the anti-static foam
• Trigger the Ground connection on and off

This makes the Netduino "touch" the iPad touchscreen. I've already tested this simple scenario and it works, but I have to physically touch the wire to Ground and remove it. I need some way of doing this with Netduino programming.

I have an iPad drums application, and my current idea is to make an automatic drum sample controller with the Netduino;

• Connect anti-static foam to each drum kit point on the iPad display
• Connect separate Grounds for each wire
• Trigger these wires individually so I can press each drum-kit item separately (high-hats, cymbals, bass drum, etc.)
• Record and play back the drum sample on the Netduino, sort of like one of those pianos that plays automatically.

This would also allow me to trigger the drum kit with other materials by using pressure sensors. Ultimately, I could use regular drum sticks on other materials to play the electronic drum kit on the iPad.

The problem I'm solving with this: the iPad display is small, and obviously I cannot smack real wooden drum sticks directly onto the iPad display, so I have to use my fingers to play the drum kit, which is not true to a real drum set, and it is cumbersome.

This would open up the ability to create a small electronic drum kit that could be played with real drum sticks. All the sounds are already there on the iPad; I just need to implement the electronic connections to "touch" the iPad display.

What do you think? Dumb idea? Cool idea? Useless idea?

Has anyone done anything like this before? Any tips?

Thanks!

Very cool idea, and a unique way of triggering the touch screen!

You should be able to just connect the wire to a GPIO, and configure it as a Tristate port, leaving it open. Then to trigger it set the port to low which will be your ground.

Try it on a breadboard. If that doesn't work you would probably need to use a relay. I doubt a transistor would work because there's not a complete circuit for the base to emitter. So it may also be true for the GPIO port that you won't get a connection to ground this way. But it can't hurt to try.

[monewwq1]

Darrin, I tried OutputPort, and nothing. I tried TriStatePort, and it triggered a couple of times, but not reliably. I'm going to try a relay now. Thanks, Nick

[monewwq1]

A relay works. The problem is that the relay contacts are not going to last very long if I use this method. Can anyone think of any other way to do this?

Netduino touches my iPad.

See video action here: Netduino triggers iPad Drums. The ticking sound is not a metronome- it is the 9vdc relay I'm using to open and close the Ground.

I also notice that if I increase the speed, sometimes it misses hits on the touchscreen. Does anyone know why? Other than the anti-static foam, should I use other materials to get a more reliable contact?

[Darrin]

A relay works. The problem is that the relay contacts are not going to last very long if I use this method. Can anyone think of any other way to do this??

Netduino touches my iPad.

See video action here: Netduino triggers iPad Drums. The ticking sound is not a metronome- it is the 9vdc relay I'm using to open and close the Ground.

I also notice that if I increase the speed, sometimes it misses hits on the touchscreen. Does anyone know why?

Nice job, that's awesome!

Next thing I'd try would be a SSR (Solid state relay), something like this: https://www.jameco.c...ductId=1583068

As far as the misses, make sure your pulse duration is long enough to fully charge the coil of the relay. You may need to add some code that ensures a minimum duration on the output pulse.

But with the SSR, you may not be quite as constrained by the timing.

[monewwq1]

Nice job, that's awesome!

Next thing I'd try would be a SSR (Solid state relay), something like this: https://www.jameco.c...ductId=1583068

Thanks again Darrin! My local shop doesn't carry SSR's, but they do have 5V Reed Relays, so while I'm waiting for the SSR's, I'll give them a try.

[CW2]

Can anyone think of any other way to do this?

How about JFET or MOSFET transistor?

[limelindfors]

Hi! I just had an idea and as I searched around to see if anyone was implementing it already, I stumbled across this. My question for you all is this: Have you thought of putting pressure sensors to the drumstick heads? I imagine a pressure sensitive drumstick wirelessly sending hit/pressure information to the iPad or whatever device. I guess you could have different surfaces for triggering different sounds. Actually what I was inspired by was SixthSense technology (http://www.ted.com/t...technology.html). In my mind I'm seeing a drumstick/SixthSense system that turns any surface to a trigger pad!

[Chris Seto]

Have you tried an NPN transistor? Remember, you will need to bring the base LOW for the ground to be "connected". Also remember to use a 1K or so current limiting resistor on the base leg.