Have you implemented your own USB devices yet? How about your own BLE based protocol? All with your own code (not using some off the shelf library which impos

Have you implemented your own USB devices yet? How about your own BLE based protocol? All with your own code (not using some off the shelf library which imposes its own abstractions on you)? I've done a moderate amount of firmware programming, and while some of it seems "easy" or "obvious" in retrospect, taking a new chip, implementing a crude task sharing "operating system", writing drivers for peripherals, then writing a host facing interface (like USB, or bluetooth) and then writing the host driver for it, and making it all happy... Eh, actually that might be more tedious than hard. The last thing I worked on that evoked "wow that was fucking hard", required minimizing the power draw without sacrificing features, so you have to deal with creating state machines to track all the various standby and power states of your peripherals and radios and mcu, and transitioning between them in the right way (and with the right timing!) Doing cool sound/music stuff used to be hard, but it's eas(ier) now that your microcontroller is frequently 32bit. Make a live update mechanism for your project that is provably un-brickable. That was difficult 10 years ago. Might still be difficult.