Introduction In fields such as large rotating machinery, bridges, underground railways, and machine tools, the acquisition and analysis of vibration signals can achieve multiple functions, including hazard prediction, fault diagnosis, and performance index analysis. Traditional portable vibration measurement and analysis instruments mostly use microcontrollers or RISC CPUs as their core processors, typically 8-bit or 16-bit, with only a few kilobytes of RAM and 1-2 megabytes of external storage. Furthermore, the CPU's clock speed is relatively low, making large-scale data processing (such as FFT) time-consuming. Image display relies primarily on a monochrome LCD screen, limiting the amount of information that can be displayed. Therefore, improving the performance of traditional portable vibration testing and analysis instruments is essential. This project utilizes the ARM9 S3C2410 processor, which can continuously monitor eight channels, providing vibration monitoring and analysis charts such as rotational speed, bar graphs, vibration frequency values, data lists, time-domain waveforms, spectrum graphs, and Bode plots. Featuring a 640×480 TFT color display screen with a beautiful interface and rich display content, this device utilizes 64Mb of RAM for storing long-term sampling data and calculation results, and 64Mb of NAND FLASH for storing multiple sets of historical measurement data. Its compact size (22cm×18cm×10cm) makes it easy to carry, and its performance is significantly improved compared to previous products. Hardware Introduction The hardware mainly consists of three parts: a core board, a baseboard, and a signal input interface board, totaling three circuit boards, which are described below. Core Board The core board mainly consists of an S3C2410 processor, 64Mb NAND FLASH (K9F1208), and 64Mb of RAM (two HY57V561620 chips). The baseboard uses a 144-pin memory slot, leading to a 16-bit data bus, a 16-bit address bus, an IIC interface, an SPI interface, an IIS interface, a JTAG interface, a USB interface, an LCD interface, a touch screen interface, and other CPU input/output lines. The S3C2410 processor is a 32-bit microcontroller from Samsung, based on the ARM920T processor core from ARM Corporation and manufactured using a 0.18μm process. This processor features: a dedicated 16KB instruction cache and 16KB data cache, an MMU, a TFT LCD controller, a NAND flash memory controller, 3 UARTs, 4 DMAs, 4 timers with PWM, I/O ports, an RTC, 8 10-bit ADCs, a touch screen interface, an IIC-BUS interface, an IIS-BUS interface, 2 USB host ports, 1 USB device port, an SD host and MMC interface, and 2 SPI interfaces. The S3C2410 processor can run at a maximum frequency of 203MHz. Its processing power is 203 × 1.1 MIPS, making it extremely fast for FFT calculations. The circuit schematic design references the ORCAD format schematic of the evaluation board provided by Samsung. Tips: Domestic hardware engineers are generally familiar with PROTEL software but not so much with ORCAD. PROTEL 2004 can directly open the ORCAD format circuit schematic of Samsung's S3C2410 evaluation board. With appropriate modifications, you can create your own PROTEL format circuit schematic, and it's less prone to errors. Therefore, the schematic design of this core board went very smoothly. PCB Design: Because the S3C2410 uses a 272-pin BGA package, the PCB was fabricated using a 6-layer PCB, from top to bottom: component layer, ground, routing layer 1, routing layer 2, ground, bottom layer. The minimum wiring spacing is 5mil, the minimum line width is 5mil, and the via size is 8/16mil. The entire core board was routed manually. Baseboard Design The baseboard mainly consists of A/D circuitry, a TFT color screen interface, a network interface circuit, and a touchscreen interface circuit. The circuits for each part are described below. The A/D chip interface with the CPU uses the AD7864, a high-speed, low-power A/D converter capable of simultaneous sampling of four channels. Its main features include: high-speed 12-bit A/D converter; simultaneous sampling of four input channels with four sample-and-hold amplifiers; 0.35μs sample-and-hold acquisition time, and 1.65μs conversion time per channel; selection of sampling channels via software or hardware; single power supply (+5V); multiple conversion voltage ranges; a high-speed parallel interface for direct connection to the processor; low power consumption (90mW per channel); and overvoltage protection circuitry for each analog input channel. When all four channels of the AD7864 are operating simultaneously, the maximum sampling rate can reach up to 130kHz. Using two AD7864 chips allows for simultaneous sampling of eight signals and monitoring of eight channels. Typical mechanical rotational speeds range from 100 to 30,000 rpm, with a maximum frequency of 500 Hz. Based on the sampling requirements of the vibration analyzer, 128 points are sampled per cycle, resulting in a sampling frequency not exceeding 64 kHz. This sampling frequency is still quite low compared to the S3C2410's CPU core frequency of 200 MHz and external data bus frequency of 100 MHz. Therefore, the falling edge of the AD7864's A/D conversion completion signal (BUSY) interrupts the CPU, and the S3C2410 directly reads the A/D converted data into memory. This avoids using external RAM to cache the A/D converted data or employing a FIFO to buffer the data before the CPU reads it from the cache. Actual test results show that even at sampling frequencies below 100 kHz, the sampled data can be read correctly without error, greatly simplifying the A/D sampling circuit design and saving circuit costs. The interface circuit design with the CPU is shown in Figure 1. AIN1-AIN8 are analog signal inputs, DATA0-DATA11 are the lower 12 bits of the S3C2410 data bus, EINT0 is connected to the 0th external interrupt line of the S3C2410, nOE is the read enable signal of the S3C2410, the chip select of the AD7864 is directly connected to NGCS1 and NGCS2 of the S3C2410, and the starting addresses of BANK1 and BANK2 are used for reading operations on the AD7864, i.e., 0x08000000 and 0x10000000. CONV_START is the sampling frequency signal, which can be an external synchronous sampling signal, sampling 128 points per cycle, or an internal asynchronous sampling signal generated by the internal PWM circuit. The S3C2410 display interface circuit has a built-in LCD driver, so the display interface design is relatively simple. The TFT display used is the Taiwan E Ink PD064VT4 screen. The PD064VT4 screen is a 640×480 high-brightness TFT color screen with a brightness of 400 Cd/m², making it very suitable for industrial applications. The signal interface is a parallel 18-bit RGB, with each color represented by a 6-bit signal. The digital interface between the TFT display and the CPU is shown in Figure 2. Figure 2: Digital Interface Between the PD064VT4 Display and the S3C2410. The S3C2410's LCD driver interface is a 24-bit RGB interface, with output signals VD0-VD7, VD8-VD15, and VD16-VD24, each color represented by an 8-bit digital signal. The PD064VT4 TFT screen interface is an 18-bit RGB interface, with each color represented by a 6-bit digital signal, i.e., R0-R5, G0-G5, and B0-B5. When connecting, VD2-VD7 are connected to B0-B5, VD10-VD15 to G0-G5, and VD18-VD23 to R0-R5. VD0, VD1, VD8, VD9, VD16, and VD17 are not used. Touchscreen Interface Circuit The human-machine interface of this vibration test analyzer uses a resistive touchscreen, coupled with a 640×480 high-brightness TFT color LCD screen, making the interface very user-friendly and easy to operate. The S3C2410 has a built-in touchscreen interface circuit, and the touchscreen interface design is relatively simple. The touchscreen interface circuit is shown in Figure 3, where YU, YL, XR, and XL represent the four interface signals of the 4-wire resistive touchscreen. Signal Input Interface Board The signal input interface board can connect to eddy current sensors or magnetoelectric sensors. The processing circuitry varies depending on the type of sensor connected. The circuitry mainly consists of low-pass and high-pass filter circuits, RMS conversion circuits, etc., outputting AC waveform signals or DC signals (gap voltage or vibration intensity). The signal input interface board also includes a phase-locked loop circuit, ensuring that the AD7864's sampling frequency is 128 times the rotational speed, i.e., sampling 128 points per cycle. The connection relationship between the signal input interface board and the baseboard is shown in Figure 4. IO1-IO7 are the eight I/O lines of the S3C2410, mainly used to select the output signal of the signal input interface board. First, it controls whether to process the signal as an eddy current sensor or a magnetoelectric sensor; then, it controls whether to output an AC waveform signal or a DC signal (gap voltage or vibration intensity). Ch01-Ch08 are the AC or DC signals output from the signal input interface board to the AD7864 for sampling. The KPH signal is the rotational speed signal, sent to the S3C2410's timer to measure the rotational speed. The CLK frequency is 128 times the KPH frequency, which is the external synchronization sampling frequency signal. It is generated by a phase-locked loop (PLL) circuit on the signal input interface board. COUT is generated by dividing the input CLK signal by 128 using the S3C2410 timer, and serves as the phase comparison signal fed back to the PLL circuit. Software Design Considering that the software only needs to complete all functions using a single task, there is no need to use an embedded real-time operating system. Furthermore, considering the high cost of commercial embedded real-time operating systems (such as VxWORKS) and the high requirements for developers of open-source embedded operating systems such as Linux, and that they are not hard real-time operating systems, an embedded real-time operating system was not adopted. This vibration test analyzer uses a 640×480 TFT true-color screen. To achieve a good display effect, basic drawing functions (drawing points, lines, circles, arcs, ellipses, rectangles, and filling) were first written. Then, functions for displaying images, simple windows, and drop-down menus were written based on this. Since the instrument's display interface is relatively simple and does not need to be as complex as a Windows window, the interface display effect is still very beautiful and meets the expected requirements. The overall flowchart is shown in Figures 5 and 6. Figure 5: Overall Software Flowchart Figure 6: Signal A/D Acquisition Flowchart Conclusion This paper details the hardware circuit design and software design process of a vibration test analyzer based on the S3C2410. It utilizes the ARM9 S3C2410 processor, which significantly improves performance compared to previous products. Due to the high core frequency and external bus frequency of the S3C2410, along with its built-in color LCD driver and touchscreen interface, the FFT operation capability is greatly enhanced, enabling real-time monitoring. This simplifies the circuit design and reduces the cost of the A/D data acquisition section. Furthermore, the human-machine interface is very user-friendly and aesthetically pleasing.