Here's how buttons on earphones work (hint: voltage dividers)

Рет қаралды 777

Ай бұрын

I just learned how the buttons on wired headphones work. I've always wondered because the 3.5mm plug has just four terminals, and they're already occupied by the left and right channels, the microphone and the common ground connection.
To my surprise, it is not difficult to make multiple buttons work using just two pins -- the microphone and ground, in this case. (Does not apply to iPhones.)
The buttons, and there can be up to four of them, use a simple voltage divider network to send commands to the phone they're connected to.
Related Android article:
source.android.com/docs/core/...
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Пікірлер: 13

@hapsti Ай бұрын

u should mention how the AC mic wave forms can be differentiated from the buttons using a coupling capacitor (or DC blocking capacitor)

@bearb1asting Ай бұрын

The cellular audio interference is amazing. I also wonder if this is why left and right audio apst always hace dofferent levels as well.

@abhiramgnair5329 Ай бұрын

nice explanation

@bob_mosavo Ай бұрын

Awesome ‼ Thanks 👍

@danilodistefanis5990 Ай бұрын

What if you press more than one at the same time?

@rahkemfleming6672 Ай бұрын

Very cool vid!

@Mounixr Ай бұрын

I liked your content keep it up🎉

@yanipro3978 Ай бұрын

Добре Вече ми е ясно ❤

@eraldylli Ай бұрын

Very nice. So, the phone has the mcu that decodes the voltages/signals, right? If there is an mcu involved, why not use regular io pins. I guess this method only uses one io pin, instead of several.

@LeftyMaker Ай бұрын

I bet it's all integrated into the audio chip, if not into the snapdragon/mediatec/whatever SoC the phone has.

@eraldylli Ай бұрын

@@LeftyMaker You must be right, it probably is a feature widely adopted decades ago. Great content, keep it up.