第三章msp430基本外設(shè)38數(shù)模轉(zhuǎn)換器

og數(shù)字量-->模擬量 Uo=Dn·UREF數(shù)字值數(shù)字值

DAC類型 --由阻值為R和2R的電阻反復(fù)級(jí)聯(lián)構(gòu)成的二進(jìn) --MSP430中的DAC12模塊采用的就是這種結(jié)構(gòu)DAC類型

7D/AD/A··· 4321

000

111DAC例如:R/2R4位DAC體系結(jié)構(gòu)--DAC話 放大 放大 揚(yáng)聲 定電壓值所需時(shí)間。最短可達(dá)0.1μS。轉(zhuǎn)換速率（SR）——–轉(zhuǎn)換器的模擬輸出值與數(shù)字輸入值同增同減DAC12所有的MSP430DAC12DAC12可直接 DAC12操作動(dòng)態(tài)范圍控制DAC分辨率8位或12(DAC12RES位滿量程輸出:1xVREF、2xVREF3xVREF(DAC12IR位和DAC12OG位輸入數(shù)據(jù)格式(DAC12DF位 000Vout=Vref×3×010Vout=Vref×2x0x1Vout=Vref×100Vout=Vref×3×110Vout=Vref×2×1X1Vout=Vref×DAC12DAC12DAC12LSELx=0:新寫入數(shù)據(jù)立即輸出DAC12LSELx=1:分組(數(shù)據(jù)被鎖存DAC12LSELx=2:數(shù)據(jù)在Timer_A的CCR1輸出信號(hào)的上升沿被鎖存DAC12LSELx=3:數(shù)據(jù)在Timer_B的CCR2輸出信號(hào)的上升沿被鎖存DAC12 DAC12輸出和DMA––這種結(jié)構(gòu)提供了更強(qiáng)的系統(tǒng)靈活性沒有必需要執(zhí)行的代碼低功耗更高的效率DAC12寄存器DAC12寄存器DAC12_xCTLDAC1264 64 3210 7575 DADAC112DADAC112R 9DAC12calibrationinitializedorinprogresswhenDAC12CALON=AC12LSEL09DAC12calibrationinitializedorinprogresswhenDAC12CALON=AC12LSEL0AC12LSEL01 12iiT8bitldDAC12_xDAT edeimer_A.OUT1

edeimer_B.OUT2DAC12寄存器DAC12_xCTL,DAC127

11 80

DAC12AC12SREFx

x

DAC12A DAC

DAC1

DAC1 2 2 1MP0 Straig DAC12off(high tGRP=12off(012off(0 1AMP0= AMP2AMP1AMP0= AMP2AMP1AMP0= AMP2AMP1AMP0= AMP2AMP1AMP0= AMP2AMP1AMP0= f:frequency(speed)I:current

Lowf/ILowf/ILowf/IMediumf/IMediumf/IHighf/I

Lowf/IMediumf/IHighf/IMediumf/IHighf/IHighf/IDAC12寄存器000001010011100101110111DAC12庫函數(shù) DAC12庫函數(shù)

(DAC12庫函數(shù)

Input Lowf/ Lowf/ Lowf/

OutputDAC12off(highZ)DAC12off(0V)Lowf/IMediumf/IHighf/I

Mediumf/ Mediumf/ Highf/

Mediumf/IHighf/IHighf/IDAC12庫函數(shù) A資源DAC12_0模塊采用VREF+作為參考電壓。因此在ADC12模式下需要

配置配置

按鈕SW2--DACDAC12配置滿量程輸出必須等于VREF+2.5V配置Timer_A寄存器每毫秒產(chǎn)生一次中斷使用ACLK時(shí)鐘信號(hào)作為時(shí)鐘源將Timer_A配置為向上計(jì)數(shù)模式，一直計(jì)數(shù)直到TAR值等于TACCR0值電壓斜坡產(chǎn)生器 暫停執(zhí)行應(yīng)用程序并且直接改變寄存器禁用DAC12EC位.這一位在之后需啟用請注意一些特殊的情況輸出0DAC12_0DAT DAC_0輸出=||=|DAC12_setData(MSP430_BASEADDRESS_DAC12_2, //DAC_0輸出DAC12_init(MSP430_BASEADDRESS_DAC12_2DAC12_VREF_INT,

P6.62.5V1DAC12_AMP_MEDIN_MEDOUT中速度/DAC12_calibrateOutput(MSP430_BASEADDRESS_DAC12_2, //中速度/電流TAR=TACCR0=

TARTACCTL0| TACTLTACLR|MC_1| 增計(jì)數(shù)模式#defineTIMER_PERIOD