18位A／D转换器AD7674及其应用

针对目前超声波测距系统对数据采集的精度、速度的要求越来越高，同时又要求接口电路简单、传输可靠性好，设计并实现了应用于采集超声波回波信号的高速数据采集系统。该系统以TMS320F2812作为主控制器．AD7674作为高速模数转换器，以SPI作为数据传输接1：2。通过对TMS320F2812和AD7674的SPI时序及控制寄存器的研究。给出了正确配置SPI模式的方法和控制过程，解决了关键线路的信号完整性问题。实际试用表明：在以40kHz超声波进行测距的系统中，误差不超过2mm，盲区控制在1cm以内，满足了高精度超声波测距系统回波信号采集的需要。

18-bit A/D converter AD7674 and its application

In consideration of the higher and higher requirement of data acquisition precision and speed on the ultrasonic measuring distance system recently,at the same time, the simple interface circuit and high reliability was also required,a high-speed data acquisition system used in collecting ultrasonic echo signals was designed and implemented. This system takes the master-control unit with TMS320F2812,takes AD7674 as the high-speed ADC, takes the data transmission connection by SPI. Through the research of TMS320F2812 and the AD7674 SPI succession and controls register,it gave the method of disposing the SPI pattern correctly and the controlled process,and solved the critical path of the signal integrity problems. Actual trial shows that in 40kHz ultrasonic ranging system, the error is not more than 2mm,the blind controlled is less than 1 cm,it meets the high-precision ultrasonic echo ranging system signal acquisition needs.