5 replies to this topic

[Budisha]

Hello.
I'm having some problems figuring out how to connect 3 buttons. I know how to connect one button, but the problem in this case is that one pole of the three buttons are connected (see picture). The buttons are soldered on a circuit board i got from an old STB. How should i connect this to the Netduino? How should i code it using interrupt ports?
Please help me.

[Stefan]

Hi Budisha and welcome to the Netduino forums!

The common pin (those 3 connected to each other) should go to ground.
The other pins can go directly to netduino, for example on pins D0, D1 and D2.

You could use these 3 lines of code:

InterruptPort button1 = new InterruptPort(Pins.GPIO_PIN_D0, true, Port.ResistorMode.PullUp, Port.InterruptMode.InterruptEdgeBoth);
InterruptPort button2 = new InterruptPort(Pins.GPIO_PIN_D1, true, Port.ResistorMode.PullUp, Port.InterruptMode.InterruptEdgeBoth);
InterruptPort button3 = new InterruptPort(Pins.GPIO_PIN_D2, true, Port.ResistorMode.PullUp, Port.InterruptMode.InterruptEdgeBoth);

[Budisha]

Hello, Stefan. Thanks for your help. It worked. I already tried connecting it this way and it didnt work. But i guess that was because i set the resistor mode to disabled.

[Chris Walker]

Hi Budisha, By setting your resistor mode to PullUp as recommended by Stefan, you're effectively putting a little bit of current onto the pin. This way, when the button is pushed and a 0V (GND) signal is asserted...your Netduino can tell the difference. Chris

[Budisha]

Thanks for the explanation, Chris. I've been having a hard time understanding what the resistor mode does.

[Stefan]

Hi Budisha , It's best explained at http://en.wikipedia....ull-up_resistor When using Port.ResistorMode.PullUp, the Netduino will emulate that circuit, so it always has a value.