基于MSP430G2211實(shí)現(xiàn)的阿簡(jiǎn)易信號(hào)發(fā)生器

1、1MSP430G2系列系列Launchpad作品開(kāi)發(fā)實(shí)例教程作品開(kāi)發(fā)實(shí)例教程 n實(shí)例名稱：實(shí)例名稱：基于基于MSP430G2211實(shí)現(xiàn)的簡(jiǎn)易信號(hào)發(fā)生器實(shí)現(xiàn)的簡(jiǎn)易信號(hào)發(fā)生器 n作作 者：者：景振華景振華n制作單位：制作單位：西安電子科技大學(xué)測(cè)控工程與儀器系西安電子科技大學(xué)測(cè)控工程與儀器系n MSP430 MSP430單片機(jī)聯(lián)合實(shí)驗(yàn)室單片機(jī)聯(lián)合實(shí)驗(yàn)室n制作時(shí)間：制作時(shí)間：20112011年年1212月月第一章第一章 作品概述作品概述2作品基本情況介紹 n本作品基于TI的LaunchPad設(shè)計(jì)了一款簡(jiǎn)易信號(hào)發(fā)生器。n選用TI的MSP430G2211這款單片機(jī)。n作品采用DDS原理實(shí)現(xiàn)信號(hào)的產(chǎn)生。n使

2、用PWM調(diào)制波模擬DAC，外加一些基本的濾波和放大電路，實(shí)現(xiàn)了可產(chǎn)生正弦波、三角波、鋸齒波的簡(jiǎn)易信號(hào)發(fā)生器。34作品相關(guān)技術(shù)參數(shù)波形種類正弦波三角波鋸齒波頻率范圍（Hz）1100頻率步進(jìn)間隔（Hz）1最大幅值Vp-p（V）8輸出阻抗（）50其他功能幅度連續(xù)可調(diào)、頻率按鍵可調(diào)、輸出使能控制、LED指示系統(tǒng)硬件框圖n整個(gè)系統(tǒng)硬件主要由TI的LaunchPad、濾波器電路模塊、增益控制模塊、按鍵菜單及LED指示燈模塊和電源模塊組成。56系統(tǒng)軟件框圖n整個(gè)系統(tǒng)的軟件主要有主函數(shù)、定時(shí)器TA中斷函數(shù)、按鍵中斷函數(shù)三個(gè)大的模塊組成。PCB板正面與背面圖正面圖7背面圖作品實(shí)物圖8第二章第二章 作品硬件系統(tǒng)設(shè)

3、計(jì)作品硬件系統(tǒng)設(shè)計(jì)910Launchpad開(kāi)發(fā)板實(shí)物圖TI的Launchpad開(kāi)發(fā)板簡(jiǎn)介nTI的MSP430G2系列Launchpad開(kāi)發(fā)板是一款適用于TI 最新MSP430G2xx 系列產(chǎn)品的完整開(kāi)發(fā)解決方案。其基于USB 的集成型仿真器可提供為全系列MSP430G2xx 器件開(kāi)發(fā)應(yīng)用所必需的所有軟、硬件。LaunchPad 具有集成的DIP插座，可支持多達(dá)20 個(gè)引腳，從而使MSP430 Value Line器件能夠簡(jiǎn)便地插入LaunchPad電路板中。此外，其還可提供板上Flash 仿真工具，以直接連接至PC 輕松進(jìn)行編程、調(diào)試和評(píng)估。此外，它還提供了從MSP430G2xx 器件到主機(jī)P

4、C 或相連目標(biāo)板的9600 波特率的UART 串行連接。1112MSP430G2系列Launchpad開(kāi)發(fā)板的特性nUSB 調(diào)試與編程接口無(wú)需驅(qū)動(dòng)即可安裝使用，且具備高達(dá)9600 波特的UART 串行通信速度 n支持所有采用PDIP14 或PDIP20 封裝的MSP430G2xx 和MSP430F20 xx 器件 n兩個(gè)通用數(shù)字I/O 引腳分別連接至綠光和紅光的LED 燈可提供視覺(jué)反饋 n兩個(gè)按鈕可實(shí)現(xiàn)用戶反饋和芯片復(fù)位n器件引腳可通過(guò)插座引出，既可以方便的用于調(diào)試，也可用來(lái)添加定制的擴(kuò)展板 MSP430G2211單片機(jī)的資源和功能n16位RISC指令集處理器n128字節(jié)RAM(數(shù)據(jù))+2K字

5、節(jié)Flash存儲(chǔ)器（代碼）n一個(gè)16位TA定時(shí)器n內(nèi)置數(shù)控振蕩器（DCO），最高頻率可達(dá)21MHzn9個(gè)雙向I/O口，每個(gè)I/O口都可以作為中斷源n自帶BOR檢測(cè)電路，能自動(dòng)避開(kāi)上電瞬間的毛刺并產(chǎn)生可靠的復(fù)位信號(hào)n內(nèi)置低功耗低頻振蕩器（VLO）n可通過(guò)軟件配置的8通道比較器13n作品中總共使用了三種電源：5V、3.6V、-5V。其中3.6V的產(chǎn)生是在1117-3.3的參考端加了二極管1N5819。-5V由負(fù)壓產(chǎn)生芯片ICL7660產(chǎn)生。14電源模塊PWM模擬DAC原理nPWM調(diào)制的本質(zhì)是改變波形中高電平的比例，實(shí)際是波形在一個(gè)周期內(nèi)的“面積”。n如果將PWM調(diào)制波進(jìn)行低通濾波，取出其直流成分（

6、平均值），濾除后的輸出電壓將線性正比于PWM的占空比。n根據(jù)這個(gè)原理可以利用PWM輸出作為低速DAC使用。15濾波電路模塊n濾波電路模塊由低通濾波電路和高通濾波電路組成。n低通濾波電路主要是對(duì)430單片機(jī)P1.2（TA0.1）輸出的PWM調(diào)制波進(jìn)行濾波，來(lái)模擬DAC的功能。濾波電路模塊nR15、R16、R17、C10、C11和C12組成三階低通濾波器。3dB點(diǎn)為600Hz，可以有效的將信號(hào)中的高頻成分濾除。n高通濾波器電路。C9和R19組成高通濾波電路，3dB點(diǎn)為362mHz，可以將信號(hào)中的直流成分有效的濾除。16幅度調(diào)節(jié)及信號(hào)輸出模塊n電路由運(yùn)算放大器LM358和一些電阻電容組成的反相放大電

7、路。其中R10是精密可調(diào)電位器，方便用戶對(duì)信號(hào)的幅度進(jìn)行調(diào)節(jié)。17菜單按鍵和指示模塊LED燈D3 黃色LED燈 D4 綠色LED燈 D5 紅色LED燈輸出波形鋸齒波三角波正弦波18第三章第三章 作品軟件系統(tǒng)設(shè)計(jì)作品軟件系統(tǒng)設(shè)計(jì)19DDS原理20 )2(sinsinoutouttfAtAStfout2對(duì)于一個(gè)頻率為fout的正弦信號(hào)Sout，可以用下式來(lái)描述：其相位為：現(xiàn)將正弦信號(hào)的相位和幅值均進(jìn)行數(shù)字化。DDS原理21clkoutclkout22ffTfclkOUT222ffMNNMffN2clkout用頻率為fclk的基準(zhǔn)時(shí)鐘對(duì)正弦信號(hào)進(jìn)行抽樣 將2切割成2N等份作為最小量化單位，從而得到的

8、數(shù)字量M為：DDS原理22Nff2clkMMAfMMAASkkN1sin11kout22sin)(sin當(dāng)M取1時(shí)，可以得到輸出信號(hào)的最小頻率步進(jìn)為 由于正弦函數(shù)為非線性函數(shù)，很難實(shí)時(shí)計(jì)算，一般通過(guò)查表的方法來(lái)快速獲得函數(shù)值。DDS在作品中的實(shí)現(xiàn)n對(duì)正弦波的幅值進(jìn)行量化，幅值選為256。之所以選擇256，是由于本作品中生成的1024個(gè)點(diǎn)的正弦波相位和幅值量化表中的數(shù)值是8位的無(wú)符號(hào)char型。n在正弦波相位和幅值量化表中存儲(chǔ)的數(shù)值相對(duì)于是以256個(gè)時(shí)鐘為總周期的PWM調(diào)制波的高電平值。n1024個(gè)量化點(diǎn)正好占用1K字節(jié)的存儲(chǔ)空間。23DDS在作品中的實(shí)現(xiàn)n在軟件中，DCO的時(shí)鐘被配置為15.2

9、5MHz，但實(shí)際測(cè)試為15.802368MHz。SMCLK的時(shí)鐘源為DCOCLK。定時(shí)器TA的時(shí)鐘源為SMCLK。定時(shí)器TA的CCR0為256，而且為了得到穩(wěn)定的幅值，讓正弦波的一個(gè)點(diǎn)持續(xù)輸出占空比相同的60個(gè)PWM波形。相當(dāng)于采樣頻率為： n則最小頻率步進(jìn)為： n當(dāng)M=2時(shí)，相當(dāng)于在1029Hz的采樣率下，一個(gè)波形只取了512個(gè)點(diǎn)，輸出波形為2Hz。所以可得 。利用此原理本作品實(shí)現(xiàn)了1到100Hz正弦波的產(chǎn)生。24Hzfclk102960*256/15802368HzHzffN121029210clkMfout主程序流程圖25定時(shí)器中斷服務(wù)程序流程圖26按鍵中斷服務(wù)程序流程圖27I/O口初始

10、化nvoid Port_init(void)nn P1SEL|=BIT2;/TA0.1n P1DIR|=BIT2;n P1DIR|=(BIT3+BIT4+BIT5);n P1OUT|=BIT5;/初始為Sine，點(diǎn)亮相應(yīng)指示燈n P1OUT&=(BIT3+BIT4);n /四個(gè)按鍵n P1DIR&=(BIT6+BIT7);n P1IES|=BIT6+BIT7;n P1IE|=BIT6+BIT7;n P2DIR&=(BIT6+BIT7);/設(shè)為輸入n P2SEL&=(BIT6+BIT7);/關(guān)閉第二功能n P2IES|=BIT6+BIT7;/下降沿觸發(fā)n P2IE|=BIT6+BIT7;/開(kāi)中斷

11、n28系統(tǒng)時(shí)鐘初始化nvoid Sys_clock_init(void)nn DCOCTL = 0 x60;/DC0=3 n BCSCTL1= 0 x8F;/0X88-RSEL=8 DCOCLK=1.6MHz 0X8F-RSEL=15 DCOCLK=15.25MHzn for(unsigned int i=0;iSin_line)n TACCR1=sinM;n M+=Delt_M;n if(M=1024) M=M-1024;n Count_line=0;n n 31nif(WaveSelect=10)/Trianglen n Count_line+;n if(Count_line3)n n i

12、f(Count1405)n n Count=2810-Count;n Rise=0;n TACCR1=Count;n Count_line=0;n return; n n n 32定時(shí)器TA中斷服務(wù)程序產(chǎn)生三角波nif(Rise=0)/三角波下降n n if(Count=f_out)Count-=f_out;n else n n Count=f_out-Count;n Rise=1;n n n TACCR1=Count;n Count_line=0;n n n 33定時(shí)器TA中斷服務(wù)程序產(chǎn)生三角波nif(WaveSelect=15)/Sawtoothn n Count_line+;n if(C

13、ount_line6)n n Count+=f_out;n if(Count=1405)Count-=1405;n TACCR1=Count;n Count_line=0;n n n34定時(shí)器TA中斷服務(wù)程序產(chǎn)生鋸齒波P1口中斷服務(wù)程序n#pragma vector=PORT1_VECTORn_interrupt void P1_ISR_KEYS(void)nn unsigned int i,Keytime1=0,Keytime2=0;n unsigned char PushKey;n PushKey=P1IFG&(BIT6+BIT7);n for(i=0;i60000)n n Keytime

14、2+;n Keytime1=0;n if(Keytime210)n n if(f_out) f_out-=5;n Keytime2=0;n n n n if(f_out) f_out-=1;n n P1IFG=0;n return;n36P1口中斷服務(wù)程序n#pragma vector=PORT2_VECTORn_interrupt void P2_ISR_KEYS(void)nn unsigned int i,Keytime1=0,Keytime2=0;n unsigned char PushKey;n PushKey=P2IFG&(BIT6+BIT7);n for(i=0;i60000)n

15、 n Keytime2+;n Keytime1=0;n if(Keytime210)n n if(f_out=100)f_out+=5;n else f_out=1; n Keytime2=0;n n n n if(f_out=100)f_out+=1;n else f_out=1;n n P2IFG=0;n return;n38P2口中斷服務(wù)程序正弦波相位和幅值量化表nconst unsigned char sin1024=n128,128,129,130,131,131,132,133,134,135,135,136,137,138,138,139,140,141,141,142,143,

16、144,145,145,146,147,148,148,149,150,151,152,152,153,154,155,155,156,157,158,158,159,160,161,161,162,163,164,164,165,166,167,167,168,169,170,170,171,172,172,173,174,175,175,176,177,178,178,179,180,180,181,182,183,183,184,185,185,186,187,187,188,189,189,190,191,191,192,193,193,194,195,195,196,197,197,

17、198,199,199,200,201,201,202,203,203,204,204,205,206,206,207,207,208,209,209,210,210,211,212,212,213,213,214,215,215,216,216,217,217,218,218,219,219,220,221,221,222,222,223,223,224,224,225,225,226,226,227,227,228,228,229,229,230,230,230,231,231,232,232,233,233,234,234,234,235,235,236,236,236,237,237,

18、238,238,238,239,239,240,240,240,241,241,241,242,242,242,243,243,243,244,244,244,245,245,245,245,246,246,246,247,247,247,247,248,248,248,248,249,249,249,249,249,250,250,250,250,251,251,251,251,251,251,252,252,252,252,252,252,252,253,253,253,253,253,253,253,253,254,254,254,254,254,254,254,254,254,254,

19、254,254,254,254,254,254,254,254,254,254,255,254,254,254,254,254,254,254,254,254,254,254,254,254,254,254,254,254,254,254,254,253,253,253,253,253,253,253,253,252,252,252,252,252,252,252,251,251,251,251,251,251,250,250,250,250,249,249,249,249,249,248,248,248,248,247,247,247,247,246,246,246,245,245,245,

20、245,244,244,244,243,243,243,242,242,242,241,241,241,240,240,240,239,239,238,238,238,237,237,236,236,236,235,235,234,234,234,233,233,232,232,231,231,230,230,230,229,229,228,228,227,227,226,226,225,225,224,224,223,223,222,222,221,221,220,219,219,218,218,217,217,216,216,215,215,214,213,213,212,212,211,

21、210,210,209,209,208,207,207,206,206,205,204,204,203,203,202,201,201,200,199,199,198,197,197,196,195,195,194,193,193,192,191,191,190,189,189,188,187,187,186,185,185,184,183,183,182,181,180,180,179,178,178,177,176,175,175,174,173,172,172,171,170,170,169,168,167,167,166,165,164,164,163,162,161,161,160,

22、159,158,158,157,156,155,155,154,153,152,152,151,150,149,148,148,147,146,145,145,144,143,142,141,141,140,139,138,138,137,136,135,135,134,133,132,131,131,130,129,128,128,127,126,125,124,124,123,122,121,120,120,119,118,117,117,116,115,114,114,113,112,111,110,110,109,108,107,107,106,105,104,103,103,102,

23、101,100,100,99,98,97,97,96,95,94,94,93,92,91,91,90,89,88,88,87,86,85,85,84,83,83,82,81,80,80,79,78,77,77,76,75,75,74,73,72,72,71,70,70,69,68,68,67,66,66,65,64,64,63,62,62,61,60,60,59,58,58,57,56,56,55,54,54,53,52,52,51,51,50,49,49,48,48,47,46,46,45,45,44,43,43,42,42,41,40,40,39,39,38,38,37,37,36,36,

24、35,34,34,33,33,32,32,31,31,30,30,29,29,28,28,27,27,26,26,25,25,25,24,24,23,23,22,22,21,21,21,20,20,19,19,19,18,18,17,17,17,16,16,15,15,15,14,14,14,13,13,13,12,12,12,11,11,11,10,10,10,10,9,9,9,8,8,8,8,7,7,7,7,6,6,6,6,6,5,5,5,5,4,4,4,4,4,4,3,3,3,3,3,3,3,2,2,2,2,2,2,2,2,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,

25、1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,3,3,3,3,3,3,3,4,4,4,4,4,4,5,5,5,5,6,6,6,6,6,7,7,7,7,8,8,8,8,9,9,9,10,10,10,10,11,11,11,12,12,12,13,13,13,14,14,14,15,15,15,16,16,17,17,17,18,18,19,19,19,20,20,21,21,21,22,22,23,23,24,24,25,25,25,26,26,27,27,28,28,29,29,30,30,31,31,32,

26、32,33,33,34,34,35,36,36,37,37,38,38,39,39,40,40,41,42,42,43,43,44,45,45,46,46,47,48,48,49,49,50,51,51,52,52,53,54,54,55,56,56,57,58,58,59,60,60,61,62,62,63,64,64,65,66,66,67,68,68,69,70,70,71,72,72,73,74,75,75,76,77,77,78,79,80,80,81,82,83,83,84,85,85,86,87,88,88,89,90,91,91,92,93,94,94,95,96,97,97,98,99,100,100,101,102,103,103,104,105,106,107,107,108,109,110,110,111,112,113,114,114,115,116,117,117,118,119,120,120,121,122,123,124,124,125,126,127;39第四章第四章 總結(jié)與思考總結(jié)與思考40總結(jié)n本文完成了基于MSP430G2211