Design And Implementation Of TDC In Ultrasonic Heat-meter

Traditional heating system induced large waste of energy owing to its low intelligence and non-based on user's requirements for self-regulation of heating time and temperature. Energy metering and charging will gradually replace the heating charge system to meet the demand for constructing an economical society of our country.An heat meter based on ultrasonic sensing technology were proposed and detailedly investigated aiming at overvoming the disadvantages of heat meters which were generally employed currently. Firstly, the paper illustrated the principle of the ultrasonic heat meter, then it present a new time-interval measurement method for the time difference with ultrasonic specially. The method exploited time to digital converter(TDC) to measure time-interval in combination with counter. It enlarged the measurement scope while ensuring high resolution and precision with system power dissipation decreasing significantly.The time-interval could be divided into two parts, namely clock synchronized part and clock unsynchronized part. Both coarse count and fine count which base on the clock and gate delay separately were used to quantify them. Thus, time variable were converted into digital variable.Based on the principle of ultrasonic heat meter and the application requirements, the function definition and structure classifying were carried out, moreover the detailed structure, the specific design and the results of simulation of each module were given. During the FPGA prototype implementation, the mannual tool for the layout namely FPGA Editor which were provided by Xinlinx cooperation were employed for the ring-delay-line design. Conforming to the FPGA prototype implementation flow, it carried out the simulation, synthesis, line disposing, and timing simulation while ensuring the correction of the function simulation and timing simulation. Furthermore, it investigated into the synthesis and timing while using the Design Compiler of Synopsys cooperation. The results fully meet the requirements. Also, This paper had DFT design for TDC through inserting a scan chain. The coverage analysis shows that, DFT fully meets the design requirements. Steps for designing DFT were put forward in addition.The main contribution of this paper are as follows:the design principle of ultrasonic energy measurement is provided and a new method of time to digital converter to measure the time-interval of the ultrasonic specially is proposed. FPGA implementation of TDC is completed. Logic synthesis and design for test are completed.