Devlog #2: a hardcoded threshold was never gonna hold up

yea so a fixed threshold on the emg envelope was never gonna hold up either.

went back and actually read the myoware docs properly instead of guessing, specifically https://learn.sparkfun.com/tutorials/getting-started-with-the-myoware-20-muscle-sensor-ecosystem/myoware-20-muscle-sensor, and turns out the board already outputs raw, rectified, and envelope in hardware, so i didnt need to build any filtering myself like i was planning last time. moved the wire off raw and onto env instead, watched the serial plotter, and it was night and day, clean baseline, clean spike on a clench. set a threshold in like ten minutes and called it a win.

came back after a break, restuck the electrodes in about the same spot, and the same threshold either pegged “flexed” the whole time or sat dead flat no matter how hard i clenched. also never wrote down where the gain trim pot was set the first time, so i cant even get back to the “clean” version on purpose right now, im just turning a knob and hoping. so, cool, a threshold that only survives as long as i never touch the sensor, my arm, or the pot again.

turns out this isnt just a me problem either, apparently even coapt’s commercial emg prosthetics need frequent recalibration for the exact same reason, contact impedance just isnt stable session to session for anyone. so a fixed number was always gonna break, i just hadnt hit it yet.

but yea, overall today i felt kinda dumb for thinking “clean signal on the plotter” meant “done,” and now im thinking the real fix is a calibration step that runs every time i put it on, flex hard for a sec, relax for a sec, threshold off whatever that session actually measures instead of a number i picked once and forgot about.