Lots and lots happened since my last post - I think I have done 5 or 10 versions before finally arriving at something that I'm (relatively) happy with.
Video first, then a couple of words.
The controller emerged as an attempt to build direct-drive robotic actuators. I did not like the complexity of the gearbox and wanted elegantly simple and smooth design. Well, it worked out very well. Unfortunately not strong enough to drive biped humanoid robot, but can be perfectly fine for other designs.
The controller measures position of the rotor via magnetic sensor and applies sinusoidal PWM at exactly +-90 deg at all times. This means that it applies constant torque in stall and close to stall situations, exactly is requires by robotics.
Size of the board was chosen to directly fit the back of BLDC camera gimbal motor which conveniently comes with magnet pre-installed. Other types or motors can be driven as long as magnet is mounted on the rotor and located close to sensor.
More information here: https://www.dizzy.ai/documentation/motor-driver/