engine management units, camera flashes, LED lights, servo motors and brushless motors to name a few. Whilst the raspberry pi has the ability generate PWM, you

engine management units, camera flashes, LED lights, servo motors and brushless motors to name a few. Whilst the raspberry pi has the ability generate PWM, you can't guarantee when they run because something else might be scheduled to be on the CPU at the time. The fancy RGB lights require a precise, complex signal running at ~800KHZ* you can't miss a signal slot because it'll change colour. Its the same for servo motors, although thats more simple as it only needs a static PWM to hold position. *might be less