Study Of The Hardware Solution Of A New Type DSP-SPM System

By analyzing the limitations of the previous SPM system in our lab, a new type SPM hardware system was developed, which was based on the TMS320C6713 DSP of TI. With it, close-loop scan of contact mode AFM had been completed. A bus-architecture was used in the system, and the system was made up of the DSP main control board, the A/D board, the D/A board, the high voltage amplifier board, the multi-function board and the power supply module. The I/O control logic of each function board was realized by CPLD. Considering the convenience of the system's upgrade and increasing function, most high perfermannce chips were used in the system. EMIF (External Memory Interface) , the glueless interface to a 16M-bit, 2-bank and a 64M-bit, 4-bank SDRAM in DSP, offers an interface for high-speed and high-density memory to system designers. The main control board used EMIF to extend an external RAM and a FLASH, and communicated with PC by USB2.0 interface. CY7C68013 was used as USB interface chip. The address of RAM,FLASH,USB and all the function boards were mapped to the DSP's CE0～CE3 space. In order to improve the precision of the system, the 16-bit A/D chip and D/A chip were used in the A/D board and D/A borad. Furthermore, a new power supply module were designed to reduce the system noise, and the high voltage amplifier board and the multi-function board were updated at the same time. At the end of this article, some prblems about the software design of the system were discussed, some flow charts of the test program were listed, and the scanning waveform and images of contact mode AFM were discussed.