8051 microcontroller를 이용한 lowpass filter 디자인

소개

(C언어로 구현하였습니다.)

8051 microcontroller와 COMPACT 51을 이용하여,
transient bandwidth를 최소화하는 FIR low pass filter를 디자인하는 과정과
결과 분석 등이 들어있습니다.

8051 microcontroller와 compact51은 실험에 사용된 CPU와 보드 이름인데,
작업은 C언어로 하였기 때문에
어떠한 embedded board에도 다 적용될 수 있습니다.
(일반 컴퓨터 PC 에서도 사용될 수 있습니다. (약간의 수정 필요))

더 높은 차수의 tap으로 에러를 줄이면서
사각 펄스에 더 가깝게 만드는 것을(narrow transient bandwidth) 구현하기 위해
코드를 optimize 하는 과정도 들어있습니다.

코드는 문서에 첨부되어 있습니다.

리포트 내용은 영어이지만 쉬운 단어들만 사용하였고,(한국인이 썼습니다. ㅋ)
소스코드가 있기 떄문에 해석은 어렵지 않을 것이라 생각됩니다.

최종 A+ 받았습니다.

목차

- Investigate the difference between digital filter and analog filter.
l What are the pros and cons of digital filter?
l What happen if the input of digital filter increases to infinity?
- Summarize the characteristic of FIR filter and IIR filter
- Investigate various windows of FIR filter
l Enumerate available windows.
l Describe characteristic of each window.
l Discuss which window is proper to this experiment.

1) What is the largest order of the FIR filter which assures successful operation?
2) What is input frequency range for which the filter output remains stable?
3) Is there any significant signal distortion or jitter? If so, discuss why.
4) Check whether the maximal sampling rate the same as your expectation.
5) Discuss on the possible difference between the filter characteristic obtained in the experiment and
that from the MATLAB
6) Enumerate ways to improve the operation speed of the filter.

본문내용

1. Purpose
-In this experiment, we try to design simple FIR filters using A/D, D/A converter on theCOMPACT51 board which is based on the 8051 microcontroller. Actually, the 8051 microcontroller is not proper to design an accurate high-order FIR filter owing to the 8051’s low complexity and performance. For this reason, the focus of this experiment is a design compromise between the performance and complexity based on the provided hardware.
- As in the previous experiment, you are recommended to try various attempts to design your own digital system rather than simply follow the given procedure in the experiment handout.

2. Problem statement
- Design FIR filters (LPF, BPF, HPF) using A/D, D/A converter on the COMPACT51 board which is based on the 8051 micro-controller.




ii) Analysis
Kaiser and Boxcar have a sharp boundary fc=0.2~0.8. Boxcar and Kaiser have rippleiser are proper.
For above reason, we would use Kaiser window in the experiment to implement the LPF.
Extra) What happen if the input of digital filter increases to infinity?
In the above answer(page 3), we considered that the problem states that the order of the digital filter is infinity. However, after reading again, we thought that this problem can mean the infinity voltage as an input. In this case, out ADC cannot resolve this high input. And following the specification in the manual, the voltages over the resolvable range are considered as the maximum value regardless how big they are. Therefore, the result will be the maximum value which can be resolved through ADC and DAC. However, in reality, if the voltage is extremely high over the limitation of the power for the device, the circuit can be burned out.

참고자료

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