【正文】 60。define WDT_MRST_8(WDTPW+WDTCNTCL+WDTIS0)define WDT_MRST_0_5(WDTPW+WDTCNTCL+WDTIS1)define WDT_MRST_0_064(WDTPW+WDTCNTCL+WDTIS1+WDTIS0)define WDT_ARST_1000(WDTPW+WDTCNTCL+WDTSSEL)define WDT_ARST_250(WDTPW+WDTCNTCL+WDTSSEL+WDTIS0)define WDT_ARST_16(WDTPW+WDTCNTCL+WDTSSEL+WDTIS1)define WDT_ARST_1_9(WDTPW+WDTCNTCL+WDTSSEL+WDTIS1+WDTIS0)下面舉一個(gè)看門(mén)狗工作于間隔定時(shí)器模式下的例子：include void main(void){WDTCTL = WDT_MDLY_32。// Set Watchdog Timer interval to ~30msSMCLK計(jì)時(shí)IE1 |= WDTIE。// Enable WDT interrupt 間隔定時(shí)器模式中斷使能P1DIR |= 0x01。// Set to output direction_BIS_SR(LPM0_bits + GIE)。// Enter LPM0 w/ interrupt}// Watchdog Timer interrupt service routinepragma vector=WDT_VECTOR__interrupt void watchdog_timer(void)//WDTIFG中斷標(biāo)志自動(dòng)清除{P1OUT ^= 0x01。// Toggle using exclusiveOR}3，上電以后看門(mén)狗默認(rèn)是打開(kāi)的，如果不用的話就將其關(guān)閉：WDTCTL = WDTPW + WDTHOLD；4，看門(mén)狗控制寄存器還控制著RST/NMI管腳的功能，可以選擇它為復(fù)位管腳，也可以選擇它產(chǎn)生不可屏蔽中斷，例子如下：//第16腳是RST/NMI/SBWTDIO在本程序中，如果按下RESER鍵，會(huì)進(jìn)入非可屏蔽中斷，使P10 led閃爍includevoid main(void){WDTCTL = WDTPW + WDTHOLD + WDTNMI + WDTNMIES。// WDT off NMI hi/lo//WDTHOLD停止看門(mén)狗定時(shí)器WDTNMI選擇RST/NMI pin為NMI功能WDTNMIES選擇下降沿觸發(fā)NMIP1DIR |= 0x01。// Set to output directionP1OUT amp。= ~0x01。// Clear LED offIE1 |= NMIIE。// Enable NMI不可屏蔽中斷使能_BIS_SR(LPM0_bits)。// Enter LPM0因?yàn)槭欠强善帘沃袛?，所以不用打開(kāi)總中斷}pragma vector=NMI_VECTOR__interrupt void nmi_ (void){volatile unsigned int i。P1OUT |= 0x01。// Set LED onfor (i = 20000。 i 0。 i)。// DelayP1OUT amp。= ~0x01。// Clear LED offIFG1 amp。= ~NMIIFG。// Reclear NMI flag in case bounce//NMI中斷標(biāo)志位必須要軟件清除IE1 |= NMIIE。// Enable NMI//當(dāng)非可屏蔽中斷被相應(yīng)，所有的NMI使能位都會(huì)自動(dòng)地被復(fù)位，所以NMI相應(yīng)之后，用戶(hù)必須軟件重新使能需要的NMI}二，MSP430G2553的應(yīng)用設(shè)計(jì)（一），頻率計(jì)的設(shè)計(jì)1，頻率計(jì)的實(shí)現(xiàn)方法有：測(cè)頻法，測(cè)周法，等精度測(cè)頻。一般是低頻用測(cè)周法較準(zhǔn)，高頻用測(cè)頻法較準(zhǔn)。等精度測(cè)頻是比較準(zhǔn)的。2，測(cè)周法：（1）可以使用定時(shí)器的輸入捕獲功能，捕獲上升沿或下降沿，然后就可以計(jì)算出信號(hào)的周期，從而得出頻率。（2）也可以把待測(cè)信號(hào)接到IO上，然后用無(wú)限循環(huán)不停的查詢(xún)電平的高低，從而得出信號(hào)的周期。丁老師建議：以丁老師的經(jīng)驗(yàn)，這種方法測(cè)量的精度比用捕獲中斷的精度要高，因?yàn)橹袛嗟倪M(jìn)入和退出都要占用時(shí)間。（3）但這種側(cè)周法適用于低頻信號(hào)頻率的測(cè)量，對(duì)于高頻信號(hào)精度不好。3，測(cè)頻法：（1）可以定時(shí)一定的時(shí)間，然后計(jì)算捕獲脈沖的個(gè)數(shù)，從而得出周期。（2）把待測(cè)信號(hào)接到IO腳上，然后用IO的中斷功能在一定時(shí)間內(nèi)記錄脈沖數(shù)。（3）設(shè)置Timer0_A的時(shí)鐘為外接時(shí)鐘TACLK，然后把待測(cè)信號(hào)接到該時(shí)鐘上，把Timer0用作計(jì)數(shù)器，在一定時(shí)間內(nèi)讀取TAR寄存器，得出脈沖個(gè)數(shù)，從而得出頻率。（4）測(cè)頻法，使用與測(cè)高頻信號(hào)，對(duì)于低頻信號(hào)誤差較大。4，等精度測(cè)頻：（1）把Timer0_A工作于計(jì)數(shù)器模式，計(jì)數(shù)待測(cè)信號(hào)。然后把Timer1_A的時(shí)鐘設(shè)為ACLK，32768Hz的標(biāo)準(zhǔn)晶振，作為標(biāo)準(zhǔn)信號(hào)。然后再外部輸入一個(gè)控制閘門(mén)信號(hào)PWM（我覺(jué)得也可以用看門(mén)狗定時(shí)器工作在間隔定時(shí)器模式來(lái)控制），和待測(cè)信號(hào)一起通過(guò)D觸發(fā)器控制計(jì)數(shù)的開(kāi)始和結(jié)束。這個(gè)外接的閘門(mén)信號(hào)可以用555振蕩器產(chǎn)生一個(gè)周期可調(diào)的PWM，這個(gè)PWM的周期不需要精確的控制，只有知道大概的范圍就可，保證計(jì)數(shù)器不溢出即可，最終測(cè)的精度和它的周期沒(méi)有絕對(duì)的關(guān)系。（也可以在計(jì)數(shù)器溢出時(shí)，在溢出中斷中記錄溢出的次數(shù)，這樣的話也可以，但是這樣中斷的進(jìn)入和退出會(huì)對(duì)測(cè)量精度產(chǎn)生影響）(2) 如果Timer0_A用于其他用途的話，也可以接一個(gè)計(jì)數(shù)器，然后把計(jì)數(shù)值在輸入給單片機(jī)（如小車(chē)上測(cè)速所采用的方法）。(3) 目前這個(gè)方案還在完善中，但初步試驗(yàn)表示，精度可以達(dá)到很高（10的4以上）(二)，DAC0832的使用1，DAC0832，我們是用在了AGC的電路中，電壓輸出受控關(guān)系為：Vref=Vin*code/256電路如下:其中0832工作于單緩沖模式，輸入寄存器受控，DAC寄存器直通一個(gè)基本的0832控制程序如下：include define uint unsigned intdefine uchar unsigned char//dac0832 pin define0832工作于單緩沖模式，輸入寄存器受控，DAC寄存器直通define CS_SET P2OUT |= BIT6define CS_CLR P2OUT amp。= ~BIT6//P26 CSdefine WR_SET P2OUT |= BIT7define WR_CLR P2OUT amp。= ~BIT7//P27 WRdefine DI P1OUT//DI//1延時(shí)//define CPU_F ((double)16000000)//cpu frequency16000000define CPU_F ((double)1000000)//cpu frequency1000000define delay_us(x) __delay_cycles((long)(CPU_F*(double)x/))define delay_ms(x) __delay_cycles((long)(CPU_F*(double)x/))void write_dac(uint data)//dac寫(xiě)數(shù)據(jù)函數(shù){CS_CLR。DI = data。WR_CLR。delay_us(1)。WR_SET。//latch dataCS_SET。}void IO_init(){P1DIR = 0xff。P2DIR |= BIT6+BIT7。//把P26和P27配置為普通IO 并為輸出腳默認(rèn)為晶振的輸入和輸出引腳P2SEL amp。= ~(BIT6+BIT7)。P2SEL2 amp。= ~(BIT6+BIT7)。}void DCO_init(){BCSCTL1 = CALBC1_1MHZ。//設(shè)定cpu時(shí)鐘DCO頻率為16MHzDCOCTL = CALDCO_1MHZ。}void main(void){// uint adc_data=0。WDTCTL = WDTPW + WDTHOLD。IO_init()。DCO_init()。write_dac(0xff)。for(。){write_dac(0xff)。delay_ms(1)。write_dac(0xc0)。delay_ms(1)。write_dac(0x7f)。delay_ms(1)。write_dac(0x3f)。delay_ms(1)。write_dac(0x00)。delay_ms(1)。}}2，0832還可以用如波形發(fā)生，原理是想0832送入不同的code，會(huì)根據(jù)上面公式輸入不同的電壓，這樣控制不同的輸入code和方式的話，就可以得到不同的電壓波形輸出，我寫(xiě)了一個(gè)程序如下：include include //dac0832 pin define0832工作于單緩沖模式，輸入寄存器受控，DAC寄存器直通define CS_SET P2OUT |= BIT6define CS_CLR P2OUT amp。= ~BIT6//P26 CSdefine WR_SET P2OUT |= BIT7define WR_CLR P2OUT amp。= ~BIT7//P27 WRdefine DI P1OUT//DIuint key=0。//按下的按鍵編號(hào)uchar s_step[]={step}。uchar s_sin[] ={sin}。uchar s_square[]={square}。uchar s_saw[]={saw}。uchar s_triangular[]={triangular}。const uchar sin_a[256]={0x80,0x83,0x86,0x89,0x8c,0x8f,0x92,0x95,0x98,0x9c,//產(chǎn)生正弦波的數(shù)組0x9f,0xa2,0xa5,0xa8,0xab,0xae,0xb0,0xb3,0xb6,0xb9,0xbc,0xbf,0xc1,0xc4,0xc7,0xc9,0xcc,0xce,0xd1,0xd3,0xd5,0xd8,0xda,0xdc,0xde,0xe0,0xe2,0xe4,0xe6,0xe8,0xea,0xec,0xed,0xef,0xf0,0xf2,0xf3,0xf4,0xf6,0xf7,0xf8,0xf9,0xfa,0xfb,0xfc,0xfc,0xfd,0xfe,0xfe,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xfe,0xfe,0xfd,0xfc,0xfc,0xfb,0xfa,0xf9,0xf8,0xf7,0xf6,0xf5,0xf3,0xf2,0xf0,0xef,0xed,0xec,0xea,0xe8,0xe6,0xe4,0xe3,0xe1,0xde,0xdc,0xda,0xd8,0xd6,0xd3,0xd1,0xce,0xcc,0xc9,0xc7,0xc4,0xc1,0xbf,0xbc,0xb9,0xb6,0xb4,0xb1,0xae,0xab,0xa8,0xa5,0xa2,0x9f,0x9c,0x99,0x96,0x92,0x8f,0x8c,0x89,0x86,0x83,0x80,0x7d,0x79,0x76,0x73,0x70,0x6d,0x6a,0x67,0x64,0x61,0x5e,0x5b,0x58,0x55,0x52,0x4f,0x4c,0x49,0x46,0x43,0x41,0x3e,0x3b,0x39,0x36,0x33,0x31,0x2e,0x2c,0x2a,0x27,0x25,0x23,0x21,0x1f,0x1d,0x1b,0x19,0x17,0x15,0x14,0x12,0x10,0xf,0xd,0xc,0xb,0x9,0x8,0x7,0x6,0x5,0x4,0x3,0x3,0x2,0x1,0x1,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x1,0x1,0x2,0x3,0x3,0x4,0x5,0x6,0x7,0x8,0x9,0xa,0xc,0xd,0xe,0x10,0x12,0x13,0x15,0x17,0x18,0x1a,0x1c,0x1e,0x20,0x23,0x25,0x27,0x29,0x2c,0x2e,0x30,0x33,0x35,0x38,0x3b,0x3d,0x40,0x43,0x46,0x48,0x4b,0x4e,0x51,0x54,0x57,0x5a,0x5d,0x60,0x63,0x66,0x69,0x6c,0x6f,0x73,0x76,0x79,0x7c}。void IO_interrupt_init()//IO中斷初始化函數(shù){P2REN |= BIT0+BIT1+BIT2+BIT5。// pullup 內(nèi)