Design of Angle Measurement System Based on CPLD and MSP430

In order to solve the problem of wide-range and high-precision angle measurement, a kind of grating-angle measurement system was designed. The grating sensor was used as output part of angle measurement signal, and the grating signal hardware decoding programme was designed applying CPLD, which achieved signal division and direction discerning and counting. The MSP430 MCU was used as control unit to achieve angle number calculation and display, communicating with CPLD by parallel bus. The design was verified its actual working effect by experiment tests, and the experiment data was finally analysized. The result showed that the system could reach 0.25mil measuring accuracy, working stably with quality of low-power and high-precision. Introduction Angle measurement is one of common problems in engineering practice, which has numerous measurement methods, and the grating measurement method is widely used at present with quality of high precision and large range. The grating measuring method applied Moire fringe principle, converting angular displacement to voltage signal orthogonal characteristics, and could further improve the measurement resolution through high-power electronic subdivision, whose measuring and decoding forms were flexible, very suitable for engineering measurement. In this paper, a kind of grating angle measurement system was designed using CPLD and MSP430 MCU as control chip. The MCU owns quality of fast processing and ultra-low power consumption, can effectively regulate the balance of system performance and power consumption; The CPLD circuit can be programmed, could parallel process signal with high-speed, which is easy to facilitate the maintenance and debug. Compared with the single MCU or CPLD as the core of the measurement system, the combined design can give full play to the ultra-low power characteristics of MSP430 MCU and CPLD high speed processing performance with greater flexibility. Overall Design The system was composed of arc-circular grating angle sensor, signal processing unit and peripheral devices. The angle sensor induced angle changes and generated grating measurement signal, the CPLD chip dealt with signal by distinguishing counting operation, as the control unit, MSP430 MCU controlled CPLD decoding function and data parallel communication, as well as completing number calculation and LCD display; The keyboard was used as input device, and the power provided same reference voltage for entire system, the whole structure was shown in figure 1. Arccircular grating angle sensor CPLD MSP 430 LCD Keyboard Lithium battery Fig.1 System structure 4th International Conference on Machinery, Materials and Information Technology Applications (ICMMITA 2016) Copyright © 2017, the Authors. Published by Atlantis Press. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/). Advances in Computer Science Research, volume 71