Abstract: In today's era of rapid development in digital technology, digital control has become an important direction for exploration and development. This paper uses the TMS320LF2407 DSP device produced by TI and the ADXL203 accelerometer sensor produced by Analog Devices to construct a signal acquisition and processing system. Based on the development process of CCS software, the system software was designed and achieved good results. Hardware anti-interference measures were adopted to effectively overcome the interference and noise caused by analog transmission. Keywords: Signal processing; Sensor; DSP; Module 1 Introduction Human technology is developing rapidly. While people are immersed in the life innovation brought by analog electronics, who could have imagined that in such a short time, we would be enjoying the greater convenience and brilliant achievements brought by digital signal processing technology? This paper mainly focuses on the application design and research of the DSP-based digital ADXL203 accelerometer sensor. The paper presents the overall scheme design, hardware circuit design and software program design of the control system. 2 System Hardware Design This system design includes: a programming logic device interface, a digital quantity expansion unit, a sensor signal generation unit, an A/D conversion unit, a power management module (providing 5V and 3.3V), and a data memory, bringing out all the resources of the TMS320LF2407. As shown in Figure 1. Figure 1 Hardware Circuit Structure Diagram. This system uses a DSP as the device for processing the accelerometer sensor signal. The TMS320LF240x controller manufactured by TI is used as the digital signal processing chip. This is a high-performance DSP chip. This DSP has many unique features in its overall structural design: First, it uses a multi-bus structure to achieve a parallel processing mechanism, allowing the CPU to access program instructions and stored data simultaneously; second, it uses independent accumulators and multipliers, enabling complex multiplication operations to run quickly; third, the accumulators and multipliers are connected to proportional shifters respectively, allowing many complex operations or post-operation scaling to be completed within a single instruction; fourth, it has rich addressing modes for convenient and flexible programming; and fifth, it has complete on-chip peripherals, allowing it to form a complete single-chip system. 2.1 AD8341 Module Based on the requirements of this system design, we selected the AD8341 analog-to-digital converter as the signal digital processing component. The AD8341 is a 16-bit, 4-channel analog-to-digital converter manufactured by Analog Devices. It features high speed and low power consumption. At 5V and a 100kHz output rate, its basic power consumption is 8mW. The reference voltage VREF can be between 500mV and VCC. Typically, VCC = +5V, VREF = +5V, fSAMPLE = 100kHz, fCLK = 24 × fSAMPLE = 2.4MHz. The clock frequency is sufficient to meet the sampling requirements of the acceleration signal. The peripheral circuit of AD8341 is shown in Figure 2. In the figure, CH1, CH2, and CH3 are connected to the output terminals of the accelerometer, representing the acceleration signals in the X, Y, and Z directions, respectively. DCLK is connected to the IOPC4 port of the DSP chip, CS is connected to the IOPE3 port of the DSP chip, DIN is connected to the IOPC3 port of the DSP chip, BUSY is connected to the IOPCS port of the DSP chip, and Dout is connected to the IOPC2 port of the DSP chip. 0.1μF and 1μF capacitors are connected to the power supply for filtering and eliminating glitches. Figure 2 AD8341 peripheral circuit diagram. 2.2 TPS7333 Power Module The TPS7333 chip is a 5V to 3.3V voltage source used with TMS320LF2407. It is small in size, has low power consumption, and stable output current. It features a low reset signal with a 200ms pulse width; very low leakage voltage, with a maximum leakage voltage of only 35mV at IO=100mA; and a maximum operating current of 0.5μA in sleep mode. The output current can reach 500mA, which is sufficient for the operation of the DSP chip. Figure 3 shows a simple peripheral hardware circuit. In a more detailed circuit, additional capacitors are needed for filtering. Since the DSP operates at a high frequency, typically 10MHz-100MHz, noise filtering is crucial. Regardless of whether the circuit board has dedicated ground and power layers, sufficient and appropriately distributed capacitors must be placed between power and ground. Generally, a number of capacitors of various capacitance values ​​are placed at the power and ground connection points on the circuit board, and the remaining large capacitors are evenly distributed along the main power and ground lines. Modern DSPs recommend using dedicated power and ground layers. Circuit boards with dedicated power and ground layers are less restrictive in terms of capacitor placement compared to double-sided boards. Capacitors of different sizes can filter out noise at different frequencies; 1-10μF capacitors can filter out 50Hz noise, and 0.01-0.1μF capacitors can filter out 100Hz noise. Figure 3. TPS333 Peripheral Circuit Diagram 2.3 Accelerometer Sensor Module Due to limitations in domestic processing technology, we can only choose existing accelerometer sensors as our research object. Here, we select the new single-chip dual-axis accelerometer ADXL203 manufactured by Analog Devices (AD) as our signal processing device. The ADXL203 adopts advanced MEMS technology and consists of a polycrystalline silicon structure using surface micromachining and a differential capacitor. Under the action of acceleration, the polycrystalline silicon structure will shift, which will pull the moving plate of the capacitor to slide, causing a change in capacitance value, ultimately resulting in a change in the output square wave. Using this principle, the change in acceleration can be detected through the differential capacitor, and the acceleration is proportional to the output square wave. Figure 4. ADXL203 Peripheral Hardware Circuit Diagram In Figure 4, capacitors C1, C2, and C3 are filter capacitors. Choosing appropriate values ​​can effectively filter out glitches generated during signal output. ST is the self-test signal output port. The applied voltage cannot exceed Vss+0.3V. After applying the voltage, a voltage of 750mV can be measured at the output terminal. Under normal circumstances, ST is unused. COM is the common port and is grounded. When Vss is 5V, the output of XOUT and YOUT is directly proportional to the acceleration. When Vss takes other values, the output voltage is as shown in Equation 1: (1) 2.4 Hardware anti-interference measures Since a large number of interference signals may be introduced into the signal acquisition and processing system, which will have a great impact on the entire system, we have considered hardware and software anti-interference measures when designing the system so that the system can work stably and efficiently. Since the experimental instruments are often affected by the interference of power grid harmonics and cannot work normally, it is necessary to minimize interference as much as possible in the experiment. Especially radiated interference and conducted interference. The hardware anti-interference measures mainly include the following aspects: (1) Using certain wiring and shielding measures to control the external interference of the system. Twisted-pair shielded wires are used for important signal lines (such as sampling signal lines) to eliminate electromagnetic interference and electrostatic interference; during wiring, logic signals and analog signals are separated, signal lines are separated from power lines, and different power supplies and ground lines are connected separately. (2) Since the DSP working frequency in this system is 10MHz, in addition to the digital signals sent to the DSP in the analog circuit being optically isolated, the analog signals sent to the A/D can also be optically isolated in a linear form. (3) Decoupling and signal isolation. Thick ground lines and power lines are used in the circuit board design, and the ground lines surround circuits with the same function. Electrolytic capacitors are connected across the power input terminal to reduce voltage fluctuations and eliminate noise. A 0.1μF high-frequency decoupling capacitor is connected to each IC chip. 3 System software design Code Composer Studio, abbreviated as CCS, is an integrated development environment (IDE) launched by TI for the development of TMS320 series DSP software. CCS works under the Windows operating system and is similar to the VC++ integrated development environment. It uses a graphical interface and provides editing tools and project management tools. It integrates various code generation tools, such as assemblers, linkers, C/C++ compilers, and library building tools, into a unified development platform. The integrated code debugging tools in CCS have various debugging functions, including all the features of the original C source code debugger and simulator provided by TI. It can perform instruction-level simulation and visualized real-time data analysis for the TMS320 series DSPs. Furthermore, it provides a rich set of input/output library functions and signal processing library functions, greatly facilitating the TMS320 series DSP software development process. The CCS integrated development environment includes design, code generation, debugging, analysis, and optimization. Users can select these tools from the menu and directly observe the compilation results in the window. To build the controller software framework, making the program easy to write, debug, test, and maintain, and easy to modify, update, and expand, a modular design is adopted, dividing the entire software into main modules such as an initialization module (including the initial settings of all basic input/output units of the DSP and the detection of external units), a signal acquisition module, and a data processing module (discrete integration, filtering, etc.). The main program uses submodule calls to coordinate the relationships between various submodules and control the system to work normally. Due to the modular design, each part is concise and clear, facilitating modification and debugging. The system's function is relatively simple: it only acquires three signals from the accelerometer, performs calculations, and saves the data. Figure 5 shows the structure diagram of the main program. The serial peripheral module configures the I/O port selection. The signal acquisition module is mainly responsible for sampling and filtering the signals through an A/D converter. The data processing module discretizes the acquired signals, derives the required values ​​using a specific algorithm, and then saves the data. The author's innovation lies in analyzing the characteristics of the ADXL203 accelerometer sensor produced by Analog Devices, and then using DSP digital signal processing to acquire, process, and save the data. References: [1] Liu Guangyu, Fan Shangchun, Zhou Haomin. Microelectromechanical Systems and Their Applications. Beijing: Beijing University of Aeronautics and Astronautics Press, 2003.6, 15-214 [2] Yang Quansheng. Modern Microcomputer Principles and Interface Technology. Beijing: Electronic Industry Press, 2002, 243-287 [3] Li Yongping, Dong Xin (eds.). PSspice Circuit Principles and Implementation. Beijing: National Defense Industry Press, 2004, 16-145 [4] Wang Ting, Shi Tielin, Zhao Jiangbin. Implementation of an IEEE1451.4 Intelligent Sensor Data Acquisition System [J]. Microcomputer Information, 2007, 2-1: 131-133