【MSP430 LaunchPad设计心得】基于MSP430G2231分辨率为0.1℃普通IO口驱动LCD的温度计-TI中文支持网

基于MSP430G2231分辨率为0.1℃普通IO口驱动LCD的温度计

wenyangzeng 2012/04/30

为了降低成本，采用MSP430G2231单片机普通IO口驱动段码型LCD，本设计使用了2个中断源,在CCR0中断中顺序产生1/2Bias的COM0－COM3位码扫描信号，并通过USI-SPI功能控制1片74HC595产生8位段码信号，驱动了4位8段LCD显示屏。在CCR1中断中清零LCD显示数据，并产生ADC允许转换信号。温度传感器则利用MSP430G2231内部温度传感器，主程序检测到ADC允许转换信号后进行一次ADC转换，通过采用过采样技术，在采样10次温度值后，进行运算，得到精度达0.1℃的温度测量结果。

设计直接利用LanuchPad 实验板扩展槽，连接1片PCB板，板上焊接74HC595和LCD和COM分压电阻等。编译环境使用IAR－MSP430 for 5.40限制版，该版本将仿真窗口中变量、寄存器观察窗的显示值都屏蔽掉了，有点太吝舍了，给调试过程带来不少麻烦。

运行结果见图1。

图1 运行结果

图2 原理图

附：代码

#include <msp430g2231.h>

#define setbit(var,bit) ((var)|=(1<<(bit)))

#define clrbit(var,bit) ((var)&=~(1<<(bit)))

unsigned char frame[4]; /* LCD frame buffer */

unsigned char digit[4]; /* Digit frame buffer */

// LCD segment definitions (SoftBaugh SBLCDA4)

#define SEG_D 0x01 // AAAA

#define SEG_C 0x04 // F B

#define SEG_B 0x40 // F B

#define SEG_A 0x80 // GGGG

#define SEG_H 0x02 // E C

#define SEG_E 0x08 // E C

#define SEG_G 0x10 // DDDD

#define SEG_F 0x20

#define DIG_c (SEG_E + SEG_G+ SEG_D) // Displays 'c'

unsigned char const number[17] = {

(SEG_B | SEG_C), // "1"

(SEG_A + SEG_B + SEG_D + SEG_E + SEG_G), // "2"

(SEG_A + SEG_B + SEG_C + SEG_D + SEG_G), // "3"

(SEG_B + SEG_C + SEG_F + SEG_G), // "4"

(SEG_A + SEG_C + SEG_D + SEG_F + SEG_G), // "5"

(SEG_A + SEG_C + SEG_D + SEG_E + SEG_F + SEG_G), // "6"

(SEG_A + SEG_B + SEG_C), // "7"

(SEG_A + SEG_B + SEG_C + SEG_D + SEG_E + SEG_F + SEG_G), // "8"

(SEG_A + SEG_B + SEG_C + SEG_D + SEG_F + SEG_G), // "9"

(SEG_A + SEG_B + SEG_C + SEG_E + SEG_F + SEG_G), // "A"

(SEG_C + SEG_D + SEG_E + SEG_F + SEG_G), // "B"

(SEG_A + SEG_D + SEG_E + SEG_F), // "C"

(SEG_B + SEG_C + SEG_D + SEG_E + SEG_G), // "D"

(SEG_A + SEG_D + SEG_E + SEG_F +SEG_G), // "E"

(SEG_A + SEG_E + SEG_F + SEG_G), // "F"

0x00 // Blank

};

long temp;

long DegC;

long IntDegC;

unsigned char Seg_Old,dispbuf[4];

unsigned char var=0,lcdcr=0,ADC_EN=0,t=0;

void display(unsigned int Number,unsigned char D_OR_H);

void main(void)

{unsigned char j=0;

WDTCTL = WDTPW + WDTHOLD;

P1OUT = 0X00;

P1DIR = 0xFF;

USICTL0 |= USIPE7 + USIPE6 + USIPE5 + USIMST + USIOE;

USICTL1 |= USICKPH;

USICKCTL = USIDIV_1 + USISSEL_2;

USICTL0 &= ~USISWRST;

USICNT = 8;

CCTL0 = OUTMOD_3 + CCIE;

CCTL1 = OUTMOD_3 + CCIE;

TACCR0 = 200;

TACTL = TASSEL_2 + MC_2 ;

ADC10CTL1 = INCH_10 ;//+ ADC10DIV_3;

ADC10CTL0 = SREF_1 + ADC10SHT_3 + REFON + ADC10ON ;

_EINT();

temp=0;

for(;;)

{

if(ADC_EN==1)

{ ADC_EN=0;

ADC10CTL0 |= ENC + ADC10SC;

while (!(ADC10IFG & ADC10CTL0));

temp += ADC10MEM;

j++;

if(j==10)

{

IntDegC = ((temp – 673) * 423) / 1024;

display(IntDegC,1);

j=0;temp=0;

}

//——————————————–

// Timer A0 interrupt service routine

//——————————————-

#pragma vector=TIMERA0_VECTOR

__interrupt void Timer_A0 (void)

{ unsigned char i;

if(var==0)

{

var++;

if(lcdcr==0)

Seg_Old=frame[0];

else

if(lcdcr==1)

Seg_Old=frame[1];

else

if(lcdcr==2)

Seg_Old=frame[2];

else

if(lcdcr==3)

Seg_Old=frame[3];

while (!(USIIFG & USICTL1));

USISRL = Seg_Old;

USICNT = 8;

for(i=4;i>0;i–);

P1OUT |= BIT4;

P1OUT &=~BIT4;

P1DIR &=~0X0F;

clrbit(P1OUT,lcdcr);

setbit(P1DIR,lcdcr);

}

else

{

var=0;

while (!(USIIFG & USICTL1));

Seg_Old=~Seg_Old;;

USISRL = Seg_Old;

USICNT = 8;

for(i=4;i>0;i–);

P1OUT |= BIT4;

P1OUT &=~BIT4;

P1DIR &=~0X0F;

setbit(P1OUT,lcdcr);

setbit(P1DIR,lcdcr);

lcdcr++;

if (lcdcr>3) lcdcr =0;

}

CCR0 += 2300;

}

//—————————————————

// Timer_A2 Interrupt Vector (TAIV) handler

//————————————————–

#pragma vector=TIMERA1_VECTOR

__interrupt void Timer_A1(void)

{

switch( TAIV )

{unsigned char i;

case 2:

{ t++;

if(t==50)

{ADC_EN=1;

t=0;

}

while (!(USIIFG & USICTL1));

USISRL = 0x00;

USICNT = 8;

for(i=4;i>0;i–);

P1OUT |= BIT4;

P1OUT &=~BIT4;

P1OUT &=~0x0f; //com全为0

P1DIR |=0X0F;

CCR1 += 2300;

break;

}

case 10: break;

}

//——————————————————

//显示4位数字函数

//入口参数1：16位数值

//入口参数2：0－16进制/1－十进制

//—————————————————–

void display(unsigned int Number,unsigned char D_OR_H)

{ unsigned char a,b,c,d;

if(D_OR_H==1)

{

a=Number%10000/1000;

b=Number%1000/100;

c=Number%100/10;

d=Number%10;

}

else

{ a=(Number>>12)&0x0f;

b=(Number>>8)&0x0f;

c=(Number>>4)&0x0f;

d=Number&0x0f;

}

dispbuf[0]= DIG_c ;//number[d];

dispbuf[1]= number[c]|SEG_H;

dispbuf[2]= number[b];

dispbuf[3]= number[a];

frame[0]=dispbuf[0]&0x03;

frame[0] |=(dispbuf[1]<<2)&0x0c;

frame[0] |=(dispbuf[2]<<4)&0x30;

frame[0] |=(dispbuf[3]<<6)&0xc0;

frame[1]=(dispbuf[0]>>2)&0x03;

frame[1] |=(dispbuf[1]&0x0c);

frame[1] |=(dispbuf[2]<<2)&0x30;

frame[1] |=(dispbuf[3]<<4)&0xc0;

frame[2] =(dispbuf[0]>>4)&0x03;

frame[2] |=(dispbuf[1]>>2)&0x0c;

frame[2] |=dispbuf[2]&0x30;

frame[2] |=(dispbuf[3]<<2)&0xc0;

frame[3] =(dispbuf[0]>>6)&0x03;

frame[3] |=(dispbuf[1]>>4)&0x0c;

frame[3] |=(dispbuf[2]>>2)&0x30;

frame[3] |=(dispbuf[3]&0xc0);

}