Let's Make Robots!

How do i use this... (underside of a button)



how do I solder a wire to this so that I can use a microcontorller to trigger it via outputs?

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I did something like that when I built my arcade controler

used an old gamepad as the "brain".

I traced the lines from the buttons to their positions on the microcontroler and soldered wires directly onto the pins of the microcontroler on the other side and then used one common ground point for the ground on my arcade buttons.


Yep. Solder direcly onto the two halves of the pad. Tiere is normally a conductor which is applied to the pad which shorts it.

Two approaches:

1) Simple, but big and more expensive: get a relay. Drive teh relay from your MCU attach the relay switch across the pads.

2) Slightly more thinking required, small, less expensive: If you can figure out which side of the switch is the common and which is the signal return, then figure out if the common is +V or Gnd, then use a transistor to apply that level to the signal return you can open and close the tranny with your MCU.

Interestingly, I'm about to blog my homebrew Frets On Fire controller which may be of some amusement...

All good fun, eh?

Here's a full-resolution closeup of my board:


I assume the button you're talking about is the one just below the RoHS logo in my picture. I remember that there was one button on the board and one button connected with wires, but I can't remember which was which. I did figure out with a multimeter that both switches worked the same way -- one side was connected to ground, and the other side presumably went to a pin on the microcontroller, so when the side that ISN'T ground gets connected to ground, that function activates. So for the button that is just on wires, it' sjust a matter of cutting the two wires, using a multimeter to find the one that's not ground, and connecting that to an I/O pin on the Arduino (configured as an output). For the other button, it works the same, except finding a place to solder to was trickier.

I determined that the left half of the split switch was ground, and the right half was the one that triggered the playback/record (whichever it is). But rather than trying to solder onto half of that intricate pattern, I just followed the trace on the board out to the right where it ends in a small test point (a contact point used by the manufacturer for testing the board). There was a small hole, but it was too small to fit a wire through, so I used a bit of clipped-off lead from one of my resistors or whatever and soldered that into the hole, and then I soldered my wire to that lead. I wasn't sure if it'd be secure enough, but it has held up fine so far. Of course, now that the board is hot-glued to the side of the robot, that wire almost never gets moved.

Here's my code for activating the sampler:

void start_sampling()
   digitalWrite(SAMPLER_RECORD_PIN, LOW);
   sample_start_time = millis();

void stop_sampling()
   digitalWrite(SAMPLER_RECORD_PIN, HIGH);
   sample_length = millis() - sample_start_time;

void play_sample()

Hope that helps.


That is exatly what I was looking for mate, well appreciated, thanks!


Ok, so I used the same method, using a resistor pin and soldered it onto the hole next to the button, I used a f/f jumper to connect this pin to an outpu on my picaxe, and used the code:


high 0
low 0
goto main 


so it would trigger the playback every second, but apparently it didnt work, please tell me what I did wrong?






the hot glue was to put the least amount of strain on the pin as possible... 


And i used my continuity tester on the pin, and underside of the button (for lack of a better term ill call it the membrane) and when i was searching for a coninutation, I found that the circuit was only complete with the half-membrane closest to the pin i made... Did I do something wrong?


I don't have time to look in detail right now, but have you connected the board's ground to the picaxe's ground? I believe I just powered mine from the gnd and 5v pins on my Arduino. The pin should only have continuity with the right half of the switch (the half closest to it), and the other half should have continuity with the GND pin on the Arduino. Does that help?


Ahh i wasnt aware that was necessary ill try it now (u mean from the 9v supply right?)


Yessir!!!! tanks!!




more important than you would believe
can't you also feed the "cathode" of the button directly via the MCU? (at the right voltage of course)

Ugh, how did Cow God do it with his drum machine?


 It appears that he didt wire to the actual button thing