Digital control of a compact disc player focus loop

This thesis gives a brief summary of the design and implementation of a digital control processor. Its architecture and some of the design had already been predetermined before the author became involved in the project. It was the intention to design a general-purpose digital control processor powerful enough to be used in research applications, and small enough to be integrated into a larger high-volume production integrated circuit. The difficulty of implementing multi-rate systems is lessened with a dedicated hardware and software solution. The design can implement z-domain filter algorithms efficiently. The digital control processor has been developed on the focus control loop of a compact disc player. A description of the relevant parts of a production compact disc player is given, and a mathematical model is derived which is suitable for computer simulation of the compact disc player. Details of the hardware interface between the compact disc player and the digital control processor are provided. The mathematical model is used in the design and simulation of a compensation filter for the focus control loop. Finally, the compensation filter is implemented and tested in the digital control processor.