I wanted a skip backwards button for audiobooks in the car so I used the android headphone button standard.
Android 3.5mm headset accessory spec says that you can have 4 buttons by putting different resistances between mic and ground.
- Function A(0Ω)
- short: play/pause
- double: next
- long: trigger assist
- Function B(240Ω): vol up
- Function C(470Ω): vol down
- Function D(135Ω): “reserved”
You supposed to do some fancy math with the mic resistance, but as I don’t intend to have a mic on this I skipped it
The hard part was getting function D to do anything. I can’t get any of the key press debugging apps I tried to register it. It definitely does things by default, like make tasker save, or close the pulldown menu. No idea what the phone thinks it is though.
“Pressy” appears to be some product that is a headphone jack and just has a single button. It’s weird that I can’t make tasker recognize it in any normal fashion, but at least now I can have it tell my media player to skip back a bit. When the question of how to make a pressy button trigger tasker is asked the responses are to use a custom app to detect it and then call tasker, which is super dumb.
Ignore the fact that I ended up with rewind on the right, I’m not resoldering it.
I haven’t used this in the car yet but it seems to be working on the bench.