使用加速度传感器应该注意几点：

第一：确保你的IIC是正确的；

第二，首先必须校准系统,校准方法，例如以下：将7455平放，保证z轴向下，这是假设系统是Ok的，那么x轴输出为0，y轴输出为0，z轴输出为63左右，假设不为以上參数，应该做例如以下调整：測量值比实际值小的情况下，往校准寄存器里面写入一个2*误差值；假设測量值假设大于实际值，应该写入一个值为相应误差的负值的ASCII码，比方假设測出值为70，那么应该写入-16，即（0xf0）；

下面就是我调试mma7455的代码：

#include "msp430f5438.h"
#include "public.h"
#include "simulate_iic.h"
#include <stdbool.h>#include "init.h"#include "mma7455.h"
#include "lcd1602.h"
#include<math.h>
typedef unsigned int uint;
typedef unsigned char uchar;
char mma7455write_byte(unsigned char reg,unsigned char data)//寄存器地址，数据
{char flag;// WDTCTL = WDTPW + WDTHOLD; // 禁止看门狗定时器iic_start();//起始信号write_byte(0x3a);//数据发送flag=get_ack();//接受应答位，即数据成功发送后，接受到的应答if(flag) {flag=0;write_byte(reg);//数据发送}flag=get_ack();//接受应答位，即数据成功发送后，接受到的应答if(flag){flag=0;write_byte(data);}flag=get_ack();if(flag){flag=0;iic_stop();return 0;}return 1;}char readMMA7455Byte(unsigned char regadd)
{char flag;char z;z=0;iic_start();write_byte(0x3a);//先写入器件地址flag=get_ack();if(flag){write_byte(regadd);//有应答之后再写寄存器地址flag=0;}flag=get_ack();if(flag){flag=0;iic_start();//继续等应答之后写入该地址和读命令，但是认为这不必要这么做write_byte(0x3b);//但是时间的原因，仅仅有找着实例的操作先写着，以后再改动}flag=get_ack();if(flag){flag=0;z=read_byte();}send_ack();iic_stop();return z;}
// X:255 1.65V -1.00g
// 012345678901234567
void Cvt_Str(char zifu[], char V1)
{char characters[17]="0123456789ABCDEF";char tv=0;tv=V1/100;zifu[2] = characters[tv];tv=(V1%100)/10;zifu[3] = characters[tv];tv=V1%10;zifu[4] = characters[tv];zifu[5] = ' ';zifu[6] = '0';zifu[7] = 'x';tv=V1/16;zifu[8] = characters[tv];tv=V1%16;zifu[9] = characters[tv];zifu[10] = ' ';if(V1>127){zifu[11] = '-';tv=255-V1;zifu[12] = characters[tv/63];zifu[13] = '.';zifu[14] = characters[((tv*100/63)%100)/10];zifu[15] = characters[(tv*100/63)%10];}else{zifu[11] = '+';tv=V1;zifu[12] = characters[tv/63];zifu[13] = '.';zifu[14] = characters[((tv*100/63)%100)/10];zifu[15] = characters[(tv*100/63)%10];}zifu[16] = 'g';
}
uint    arc_tan2(uchar Ax,uchar Ay)
{int    diat_t;float        m;m=atan2(Ay,Ax);diat_t=(int)(m*1800/3.14);return diat_t;
}
uint measure()
{uchar x;uchar y;uint x1,y1;uchar   xsign,ysign;uint angle;angle=0;x=readMMA7455Byte(0x06);y=readMMA7455Byte(0x07);x=x+0x2C;y=y+0x25;if(x>127){x=255-x;x1=((float)x*100)/63.0;xsign=0x2b;}else{x1=((float)x*100)/63.0;xsign=0x2d;}if(y>127){y=255-y;y1=((float)y*100)/63.0;ysign=0x2b;}else{y1=((float)y*100)/63.0;ysign=0x2d;}angle = arc_tan2(x1,y1);/*if(xsign==0x2b&&ysign==0x2b){angle = arc_tan2(x1,y1);}else    if(xsign==0x2b&&ysign==0x2d){angle = 900+arc_tan2(y1,x1);;}else   if(xsign==0x2d&&ysign==0x2d){angle = 2700-angle;}else  if(xsign==0x2d&&ysign==0x2b){angle = 2700+angle;}*/return angle;
}
void main()
{char txtbuf[16]="X:255 -1.00g";//uchar x,y,x2,y2;//volatile uint x1,y1;// uchar j,k;clk_init();lcd1602_pin_init();lcd_init();delay_ms(50);while(mma7455write_byte(0x16,0x005));while(mma7455write_byte(0x10,0xff));//校正X值while(mma7455write_byte(0x11,0x07));while(mma7455write_byte(0x12,0x18));//校正Y值while(mma7455write_byte(0x14,0xDC));//校正Z值while(mma7455write_byte(0x15,0xFF));while(1){/*lcd_pos(0,0);lcd_wdat('a');lcd_wdat('n');lcd_wdat('g');lcd_wdat('l');lcd_wdat('e');lcd_wdat(':');lcd_printf(measure());//x//delay_ms(1000);//lcd_wcmd(0x01);    */      //显示清屏/*x=readMMA7455Byte(0x06);y=readMMA7455Byte(0x07);x2=x+0x2C;y2=y+0x25;x=x+0x2C;y=y+0x25;if(x>0x7f){x=255-x;j=1;x1=((float)x*100)/63.0;}else{x1=((float)x*100)/63.0;j=0;}if(y>0x7f){y=255-y;y1=((float)y*100)/63.0;k=1;}else{y1=((float)y*100)/63.0;k=0;}lcd_pos(0,0);if(j==1) lcd_wdat('-');else lcd_wdat('+');lcd_char(x1);lcd_pos(0,1);if(k==1) lcd_wdat('-');else lcd_wdat('+');lcd_char(y1);delay_ms(1000);lcd_wcmd(0x01);lcd_pos(0,0);Cvt_Str(txtbuf,x2);txtbuf[0]='X';lcd_string(txtbuf);lcd_pos(0,1);Cvt_Str(txtbuf,y2);txtbuf[0]='Y';lcd_string(txtbuf);delay_ms(1000);lcd_wcmd(0x01);*/            //显示清屏lcd_pos(0,0);Cvt_Str(txtbuf,readMMA7455Byte(0x08));txtbuf[0]='Z';lcd_string(txtbuf);lcd_pos(0,1);lcd_printf(arc_tan2(readMMA7455Byte(0x08),readMMA7455Byte(0x06)));delay_ms(1000);lcd_wcmd(0x01);          //显示清屏lcd_pos(0,1);Cvt_Str(txtbuf,readMMA7455Byte(0x06));txtbuf[0]='X';lcd_string(txtbuf);lcd_pos(0,0);Cvt_Str(txtbuf,readMMA7455Byte(0x07));txtbuf[0]='Y';lcd_string(txtbuf);delay_ms(1000);lcd_wcmd(0x01);          //显示清屏}
}