A digital signal processor based atomic force microscope controller

This article describes the hardware architecture and software algorithms of a digital AFM controller that is built upon a digital signal processor DSP56001 from Motorola. The hardware of the digital controller includes a DSP board, a host-PC and a custom design analog/digital interface circuit board. The system has 0.4 Å/bit resolution in the vertical direction and 130 nm to 7000 nm field of view horizontally. The DSP is responsible for the operations of the AFM while the host-PC serves as a dual purpose graphical user interface for displaying the real time image and providing a menu driven panel to input the control parameters. The data communication between the DSP and the host-PC is done through hardware interrupt and is discussed in this article. Two scan algorithms are implemented and included in this article to show the flexibility of the digital controller