The Parallax Propeller is one microcontroller that could (in theory) work for bitbanging precise timings even when something else controls the timing. Since ea

The Parallax Propeller is one microcontroller that could (in theory) work for bitbanging precise timings even when something else controls the timing. Since each task can be put on a dedicated core, you could clock-count your assembly instructions to sync up with the right time windows, and offload any variable-time tasks to a different routine on another core. The only caveat is access to the central memory store inside the microcontroller is round-robin (80MHz / 8 cores), so if the timing requirement was close to that limit (1/10MHz), you might have to do some gymnastics to make sure your routine grabs the right distribution of cores to get auspicious timing, and possibly reset and try again if that can't be achieved.