A concept for implementing digital control is described which is simple and cheap, and yet makes it possible for high performance to be achieved by employing a number of 'single chip micro-controllers'. The scheme is versatile, the key being that for each feedback loop a separate micro-controller is used, each having an associated analogue-to-digital converter. Each micro-controller runs asynchronously, with internal communication being provided to transfer data from one control loop to the next.
