Portable 20M Digital Oscilloscope Implementation Based On MCU And FPGA

Digital oscilloscopes play an important role in the electronics industry. It is widely applied in the measuring field, teaching and research. However, the current digital oscilloscopes on the market are expensive and low quality-value ratio. Designing a practical digital oscilloscope with low cost is the main content of this dissertation. Based on this thoughtfulness, the AVR MCU is designed as the control center. The signal passes through the conditioning circuit which located in the front part. It is mainly composed of signal attenuation circuit and signal amplification circuit. The voltage is adjusted to the input voltage range of AD through the conditioning circuit. Then, signal goes through the sampling circuit, which fulfills the real-time waveform sampling, data processing and storage displaying. The FPGA series chips provide clock frequency for main control chips such as CPU, AD chips and memory chips FIFO. Finally, the signal is delivered to display.In addition, the FPGA also provides an opportunity of key switch for CPU. The advantages of this scheme lie in the lower cost, flexibility and smaller system scale. However, it is difficult to achieve real-time signal processing and displaying because of the limited MCU speed. Although covered frequency is less than actual requirements due to certain conditions and technical restrictions, it is still within the allowed range.The experimental results have shown that the digital oscilloscope designed in this way is able to fulfill the accurate real-time sampling and displaying for low frequency. It could be powered by battery and it has small volume. So it was convenient to carry. Besides, it can become a part of experiment box to form a whole with other function modules. Because it is designed by combing FPGA with MCU, the designation of digital memory is more flexible, the response speed is faster and the relevant improvements are more easily made in terms of personal needs, such as the further expansion of the peripheral circuit and so on.