With the continuous development of industrial automation, product quality monitoring and control have become an indispensable part of ensuring product quality standards. Many products with high assembly requirements also have limits on the impact they can withstand during transportation. Impacts exceeding these limits will damage the product and cause unnecessary losses to the company. To monitor the transportation process, the common practice is to install an impact recorder along with the product. Currently, the most widely used impact recorders in China are mechanical impact recorders. Their internal structure resembles a camera, with two paper tape reels. The recording paper tape is placed into the upper reel, and the beginning of the tape is inserted into the lower reel. Above the paper tape is a metal beam that holds three recording pens, which record the impact force along the X, Y, and Z axes. The main disadvantages of this type of mechanical impact recorder are as follows: Mechanical impact recording has a limited paper length, thus limiting the amount of impact data that can be recorded; it lacks date and time markers, only providing a time coordinate; the recorded impact range is only ±5g, failing to meet the ±10g requirements of higher standards (such as the State Grid Corporation of China); to meet the requirements of three-dimensional detection, three units need to be installed simultaneously, which is inconvenient for installation and data retrieval; mechanical impact recorders use pressure-sensitive recording paper, which is scarce domestically, and the paper frequently jams or becomes damp during humid seasons or in certain regions, leading to serious data loss; during transportation, factors such as excessive vibration amplitude and frequency during ocean transport, and the need to traverse different modes of transport (railway and road) to reach the installation site, often result in insufficient paper length, running out of paper before reaching the destination and losing much important data. With the rapid development of microelectronics technology, especially the rapid advancement of electronic accelerometer technology and microcontroller technology, electronic intelligent impact recorders have emerged, providing reliable protection for the transportation of high-precision products and supporting the development of intelligent freight vehicle technology. [IMG=Block Diagram of Impact Recorder]/uploadpic/THESIS/2007/12/2007121510130293404B.jpg[/IMG] Figure 1: Block Diagram of Impact Recorder Overall Design Scheme of Impact Recorder This paper designs an impact recorder based on an electronic accelerometer. Its schematic diagram is shown in Figure 1, including an MPS430 microcontroller and development board, data storage unit, real-time clock unit, watchdog unit, accelerometer, signal amplification and filtering unit, A/D conversion unit, as well as PC communication interface, power interface, LCD display interface, and microcontroller ISP (In-System Programming) interface. In the design and implementation of this impact recorder, the following main issues were addressed: selection of the accelerometer, selection of low-power chips, and design of the motherboard circuit. Selection of Accelerometer An accelerometer is an electronic device that can measure acceleration force. Acceleration force is the force acting on an object during acceleration. Acceleration force can be constant or variable. The basic principle of an accelerometer is that acceleration causes deformation in a medium. The amount of deformation is measured and converted into a voltage output using relevant circuitry. With the rapid development of microelectronics technology, low-cost, high-performance electronic accelerometers have emerged. Electronic accelerometers are generally classified into three types: piezoelectric, capacitive, and thermal. Piezoelectric accelerometers utilize the piezoelectric effect. Inside, there is a rigidly supported mass. When the mass moves, it generates pressure, causing strain in the rigid body, converting acceleration into an electrical signal output. Capacitive accelerometers also contain a mass. From a single unit perspective, it is a standard parallel-plate capacitor. Changes in acceleration cause the moving mass to move, thus changing the distance and facing area of ​​the capacitor's electrodes. Acceleration is calculated by measuring the change in capacitance. Thermal accelerometers have no internal mass; instead, they contain a central heating element surrounded by temperature sensors, and an internal sealed gas chamber. During operation, the heating element causes the gas inside to form a hot gas cloud. The difference in density between this hot gas cloud and the surrounding cold air creates a thermal field change through the inertial movement of this hot gas cloud, which the sensor detects as acceleration. Because piezoelectric accelerometers have rigid internal supports, they can typically only detect dynamic acceleration, not static acceleration (gravitational acceleration). Capacitive and thermal accelerometers, however, can detect both dynamic and static acceleration. Due to the absence of moving parts and the use of micromachining technology, thermal accelerometers overcame many manufacturing challenges during their development. They offer low production costs, strong shock resistance, and high reliability, with a failure rate below 10 ppm. Thermal accelerometers are small, consume low power (operating current below 2 mA), and have a standard digital interface on their main chip. It can provide acceleration values ​​in two directions, and three-dimensional acceleration measurement can be achieved using only two chips. After comprehensive comparison, this project decided to use a thermal accelerometer as the design basis. Selection of Low-Power Chips Mechanical impact recorders have the unique advantage of not operating unless an impact occurs, only operating once per vibration. Portable impact recorders, however, are battery-powered and operate continuously regardless of whether an impact occurs. Therefore, the power consumption of electronic components becomes the main issue affecting the operating time of electronic impact recorders. The microcontroller, as the core component of the circuit, has a significant impact on the overall performance. After comparative research, the TI MSP430, a new type of microcontroller employing the latest low-power technology, was deemed suitable for use in impact recorders. The MSP430 operates from 1.8 to 3.6V, with a normal operating mode (AM) and four low-power operating modes (LPM1, LPM2, LPM3, LPM4). At a 3V supply, the operating current for each mode is AM: 340uA, LPM1: 70uA, LPM2: 17uA, LPM3: 2uA, and LPM4: 0.1uA, respectively. The microcontroller can easily switch between these modes, making it particularly suitable for battery-powered and portable devices. The MSP430 also boasts high integration, integrating a multi-channel 12-bit A/D converter, an on-chip precision comparator, multiple timers with PWM functionality, a beveled A/D converter, an on-chip USART, a watchdog timer, an on-chip digitally controlled oscillator (DCO), and numerous I/O ports. The MSP430 has a large-capacity on-chip memory available in four types: ROM (C-type), OTP (P-type), EPROM (E-type), and Flash Memory (F-type). Peripheral components and circuits utilize ultra-low-power VMOS chips for all memories to achieve extremely low overall power consumption. Motherboard Circuit Design A dual-CPU design significantly reduces hardware circuitry, simplifying decoding and logic transformations, resulting in a smaller system hardware load. Simultaneously, software resource allocation and design are relatively independent, facilitating program modification. Features include a random LCD display and random touch-sensitive buttons; a sampling frequency exceeding 100,000 samples per second for continuous sampling, ensuring no vibration is missed; permanent data storage; data is retained even during power outages; data is stored and displayed in descending order for easy retrieval; and it can connect to a GPS satellite positioning system, simultaneously displaying impact data, impact location, and time. Low-Power Control Technology With the main low-power chips in place, low-power control technology is crucial in the design. Power consumption is controlled via software, prioritizing standby operation . The MSP430 microcontroller offers four low-power operating modes, resulting in significant power savings. The microcontroller enters standby or power-down mode when not in use, and is woken up when needed. After the instrument detects a prolonged period of stillness, the system enters standby mode. Upon initiation of movement, the sensor outputs a signal, and the front-end circuit of the sensor output signal changes to wake up the microcontroller. This management method significantly reduces power consumption when not in use, effectively extending the continuous working time of the entire device on a single charge. It also effectively controls the power consumption of peripheral devices and circuits. Power consumption of peripheral devices and circuits is managed by putting them into a sustaining state or stopping power supply when not in use, thus reducing power consumption. In microcontroller application systems, memory consumes a relatively large amount of power; setting the memory state to a sustaining state during standby significantly reduces power consumption. Fast algorithms are selected. For the specific problems such as the data to be processed in this project, a new algorithm with fast processing speed and high accuracy is appropriately selected to reduce CPU runtime. Timer interrupts should be used instead of software delays whenever possible . In intermittent measurement situations, external interrupts or internal timer/counter interrupts should be used, and software delays should be avoided to reduce CPU runtime. When the external interrupt sources of a microcontroller are insufficient, they can be easily expanded. Use static displays instead of dynamic displays whenever possible . Select LCD display components with data latching, decoding, driving, and display functions. As long as the component is powered on, the data is retained and the content is continuously displayed until the microcontroller refreshes it. Shorten communication time. When communicating via an RS-232 interface, if the amount of data is large, the transmission baud rate should be increased to shorten the communication time. Use high-efficiency encoding methods, such as BCD code, which is twice as efficient as ASCII code. Avoid looping during sending and receiving; use serial interrupts instead. Soften hardware . Traditional hardware filtering circuits (such as active filters) consume considerable power, and it is difficult to control their power consumption when not in use, resulting in relatively high power consumption. Using software filtering can overcome this drawback. Reduce clock frequency . While meeting the requirements for processing speed, reducing the clock frequency as much as possible can reduce power consumption. Reducing the clock frequency without sacrificing processing speed is one of the characteristics of current microcontroller technology development. Lowering the Power Supply Voltage When the operating voltage of peripheral devices and circuits cannot be lowered to the lower limit of the microcontroller's operating voltage, or when the lower limits of the operating voltages of different circuits are not entirely the same, direct battery power is not possible as with a microcontroller. A DC-DC converter can be used instead. There are many types of DC-DC converter chips, broadly categorized as boost, buck, and polarity-inverting types. They offer flexible power supply options, high conversion efficiency (many chips reach over 90%), small size, and ease of use. Anti-interference Measures Various types of interference exist in the recording environment, which may affect the reliability and accuracy of the recording. Anti-interference measures must be adopted to ensure stable operation of the recorder. The impact recorder designed in this paper uses a shielding mesh to effectively prevent interference from external electromagnetic signals during operation. GPS satellite positioning systems are not included. Conclusion Traditional impact recorders, regardless of accuracy or ease of use, are limited by their structure, making it difficult to achieve multi-functionality. Fully electronic and intelligent operation is the future direction. The impact recorder designed and implemented in this paper is an exploration in this direction. It is believed that with the continuous progress of electronic acceleration sensors and the rapid development of chip technology, the impact recorder will continue to enrich and expand its functions, providing more reliable protection for intelligent transportation and fields that require vibration control.