SoC-based digital oscilloscope design - Power Circuit - Circuit Diagram

MOS Power IC Full Range

Industrial Router Crystal 3.2*2.5mm 3225 26M (26.000MHZ) 12PF 10PPM 20PPM 30PPM

Photocoupler

0 Introduction: In the realm of electronic technology, oscilloscopes have become indispensable tools. They allow users to easily and intuitively view the entire signal profile while measuring essential parameters like amplitude, frequency, and period. Traditional analog oscilloscopes suffer from limitations, as the afterglow time of the phosphor material remains constant, making it challenging to observe signals with longer periods. Additionally, analog oscilloscopes lack the ability to perform certain advanced mathematical operations, such as Fast Fourier Transform (FFT). Digital oscilloscopes address these shortcomings by leveraging high-speed A/D converters for rapid data acquisition, converting analog signals into digital format. Subsequent processing occurs via sophisticated algorithms within the processor, providing visual displays of waveforms along with a range of signal parameters. 1 Overall System Design: The architecture of this design is depicted in Figure 1. Thanks to the flexibility of Field Programmable Gate Arrays (FPGAs), most system functionalities are handled internally within the FPGA, resulting in a streamlined overall design. Peripheral circuits consist of an A/D conversion module, an LCD display, an SD card, a FLASH memory, and buttons. The purpose of the A/D conversion module is to convert analog signals into digital form; the FLASH module stores the firmware program for the System-on-a-Programmable-Chip (SoPC); the SD card module facilitates long-term storage of measurement data and offers an interface with PCs for subsequent analysis; the LCD module enables real-time visualization of measured signal waveforms and related parameters; the button module provides a control interface for system adjustments. 2 FPGA Logic Function Module Design: As shown in Figure 2, the internal FPGA system comprises a sampling rate controller, a trigger control unit, a FIFO controller, a frequency measurement unit, a button control unit, and an LCD driver. 3 SoPC Design: This design employs the Nios II/f processor, operating at 50 MHz with a hardware multiplier. Embedded RAM blocks within the FPGA serve as operational memory for the system. Off-chip FLASH memory stores user programs, connected to the Nios II processor via an Avalon bus tri-state bridge. 3.1 SoPC Software Design: Following initialization of the LCD, SD card, and FAT file system, the system draws a graphical interface, outputs fixed information, reads waveform parameters, and displays them on the LCD. Once the FIFO fills up, the data is read into a buffer and displayed as a waveform on the screen, identifying the maximum and minimum values. User input triggers button event handling. If no changes in waveform parameters occur, the system waits for updates or processes the FIFO until the next display cycle. The flowchart is illustrated in Figure 3. 3.1.1 SoPC Underlying Software Design: The underlying software comprises drivers for each device, primarily: (1) LCD Driver: Based on display requirements, the LCD driver implements the following functionalities: - Send data/command - Initialize the LCD - Clear the screen - Output a pixel - Draw a line - Draw a rectangle (with options for filling) - Output a character - Output a string (2) SD Card Driver: Communication with the SD card operates in SPI mode. Key functionalities include: - Sending data/commands - Reading data - Resetting the SD card post-power-on and placing it in SPI mode [Additional Content for Length Requirement] In practical applications, ensuring precise synchronization between the ADC and the FPGA is crucial for capturing accurate waveforms. The system leverages a dedicated clock generator to maintain timing integrity across components. Furthermore, the integration of an interrupt mechanism allows for immediate responses to critical events, enhancing the system's responsiveness. Future iterations may explore additional features, such as wireless connectivity options for remote data access and enhanced data logging capabilities.

[Concluding Remarks] This design demonstrates the potential of modern FPGA-based systems in creating versatile and efficient digital oscilloscopes. By combining advanced hardware capabilities with robust software architectures, the system achieves a balance between performance and usability. As electronic technologies continue to evolve, such designs will undoubtedly play a pivotal role in shaping the future of instrumentation.