The development of CPLD-based ultrasonic flowmeter

The measurement principle of the transit time difference method of the ultrasonic flowmeter is presented. The hardware structure and realization method are introduced. The software function and work mode are overviewed. In order to enhancing flowmeter's precision and stability a Xilinx CoolRunner CPLD and a Texas Instruments microcontroller from MSP430 family are applied in high precision timing, complex logical control and communication. The result is a low cost portable solution working with a 3.3V supply and operating with ultrasonic transducers at 1MHz frequency.