Lecture 8 digital waveform generator using u controller
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Lecture 8 Digital waveform generator using u-controller. 2007/11/09 Prof. C.M. Kyung. Experimental Goal. GOAL is to get familiar with.. Intel 8051 microcontroller The concept of D/A converter The concept of Timer Function generator Sine wave, square wave. D/A Converter : DAC0800.

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Lecture 8 digital waveform generator using u controller

Lecture 8Digital waveform generator using u-controller

2007/11/09

Prof. C.M. Kyung


Experimental goal

Experimental Goal

  • GOAL is to get familiar with..

    • Intel 8051 microcontroller

    • The concept of D/A converter

    • The concept of Timer

    • Function generator

      • Sine wave, square wave


D a converter dac0800

D/A Converter : DAC0800

  • Fast settling output current: 100 ns

  • Full scale error: ±1 LSB

  • Nonlinearity over temperature: ±0.1%

  • Full scale current drift: ±10 ppm/°C

  • High output compliance: −10V to +18V

  • Complementary current outputs

  • Interface directly with TTL, CMOS, PMOS and others

  • 2 quadrant wide range multiplying capability

  • Wide power supply range: ±4.5V to ±18V

  • Low power consumption: 33 mW at ±5V

  • Low cost


Lecture 8 digital waveform generator using u controller

D/A Converter : DAC0800

  • Top Architecture of DAC


Dac interface circuit

DAC Interface Circuit

Oscilloscope

0101100

8051

MCU

74F573

Flip-Flop

DAC0800

DAC

Digital Value

Latched

Digital Value

Analog

Output


Dac interface circuit1

DAC Interface Circuit


Dac interface circuit2

DAC Interface Circuit

  • C100H mapping

    • cmpact51.h 참조

    • unsigned char xdata DAC_0800 _at_ 0xC100;

  • 수학함수 library 이용

    • Sine function 이용 @ <math.h>

    • Floating point 연산  속도 느림

    • Specification에 알맞은 방법 찾아보기


Timer counter

Timer / Counter

  • Count the machine cycle (1/12 of internal system cycle) or external clock / event

  • When the 8bit or 16bit timer overflows, timer interrupt occurs

  • 8051 has 2 timers – Timer0, Timer1

  • Timers are controlled by TMOD, TCON registers

  • 4 modes are available


Timer module

Timer Module

  • Timer Interface Circuit


Timer mode

Timer Mode

  • Mode0

    • 8bit TH0 / lower 5bit TL0

  • Mode1

    • 16bit timer TH0/TL0

  • Mode2

    • 8bit timer with auto reload

  • Mode3

    • Separated 8bit TH0 / 8bit TL0


Timer mode1

Timer Mode


Timer mode2

Timer Mode

  • Mode2

    • TL 8bit counter 사용

    • Auto reload 지원

      • Overflow bit setting 

        • 사용자가 TF clear

        • TH에 저장되어 있는 값이 TL로 auto reload

      • Auto reload는 수동 reload보다 정확하다.

    • Timer 주기가 짧은 경우에만 사용 가능


Timer registers

Timer Registers


Problem state 1

Problem State 1

  • Sine wave generation

    • 한 주기 내에 샘플의 개수 선택, 또는 타이머 인터럽트 주기 결정

    • COMPACT51 보드로 만들 수 있는 정현파의 최대주파수

    • 버튼을 누를 때마다 주파수가 바뀌는 정현파 발생기 만들어보기


Problem state 2

Problem State 2

  • Square wave generation

    • 한 주기 내에 샘플의 개수 선택, 또는 타이머 인터럽트 주기 결정

    • COMPACT51 보드로 만들 수 있는 구형파의 최대주파수

    • 버튼을 누를 때마다 주파수가 바뀌는 구형파 발생기 만들어보기


Experiment requirements

Experiment Requirements

  • COMPACT51 보드

  • KEIL uVisionII 프로그램

  • PC

  • PC 와 COMPACT51 보드를 연결하기 위한 UART cable

  • Oscilloscope


References contact

References & Contact

  • Textbook

    • 8051 user’s manual

    • 8255 user’s manual

    • 8051 & C Programming, 문왕환, 도서출판 세화

    • DAC0800/DAC0804 manual

    • COMPACT51 실험보드 회로도

    • cmpt51.h 헤더파일

    • KEIL uVisionIII 매뉴얼 (HELP)

  • 7th Week T.A. E-mail

  • Lecture Homepage

    • http://wink.kaist.ac.kr/course/ee306/


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