Eco-friendly hardware hacking with android
summary
Uses a regular Android phone/tablet plus plain Java and an OTG adapter to control scrap hardware no firmware just Java and USB OTG keyboard LED via control transfer — writes to endpoint 0 (HID set_report) to toggle keyboard LEDs, measures roughly 1 kHz signal (≈2000 API calls/sec for on+off) but with jitter, adds a scavenged optocoupler for galvanic isolation and drives an ATX PS_ON line to switch 12 V to a motor, digital inputs come from keyboard matrix scan codes, and the build works with caveats about charging and noise.
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chapters (26)
- 0:00Intro
- 0:11Code in Movies
- 0:33Super Heroes
- 1:53mission
- 3:35Choices, choices...
- 4:55LEDs in common USB scraps
- 5:39And the winner is.
- 7:09OTG Adapter (make or buy)
- 10:20The software side
- 11:47The missing endpoint
- 14:227.2.2 SET REPORT
- 15:16For LEDs / Keyboards
- 16:03Sending the report
- 17:02Sketch of the code
- 23:36Kill the noise
- 24:58Conclusions from detour
- 27:41The ubiquitous optoisolator
- 28:33A small step forward
- 28:49A level of indirection...
- 29:48ATX is your best friend
- 30:11ATX starts in stand-by
- 32:46What about inputs??
- 33:22Relevant code
- 35:35Missing galvanic isolation!
- 36:26Charging while in host mode
- 37:57May or may not work for you
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