在keil中输入该地址，找到该地址，
上图框中前100个字节就是printf函数里的字符串，通过ascall表可以知道每个字节翻译过来加起来就代表了该字符串
上面是找了RO-data的地址位置
下面找一下RW-data和ZI-data的位置，根据之前的描述，他们分别是全局初始化变量和静态变量、未初始化的全局变量；
如下代码：
#include <math.h>
#include "stdbool.h"
#include "SysTick.h"
#include "myiic.h"
#include "bmp280.h"
#include "usart.h"
/*bmp280 气压和温度过采样 工作模式*/
#define BMP280_PRESSURE_OSR (BMP280_OVERSAMP_8X)
#define BMP280_TEMPERATURE_OSR (BMP280_OVERSAMP_16X)
#define BMP280_MODE (BMP280_PRESSURE_OSR<<2|BMP280_TEMPERATURE_OSR<<5|BMP280_NORMAL_MODE)
typedef struct
{
u16 dig_T1; /* calibration T1 data */
s16 dig_T2; /* calibration T2 data */
s16 dig_T3; /* calibration T3 data */
u16 dig_P1; /* calibration P1 data */
s16 dig_P2; /* calibration P2 data */
s16 dig_P3; /* calibration P3 data */
s16 dig_P4; /* calibration P4 data */
s16 dig_P5; /* calibration P5 data */
s16 dig_P6; /* calibration P6 data */
s16 dig_P7; /* calibration P7 data */
s16 dig_P8; /* calibration P8 data */
s16 dig_P9; /* calibration P9 data */
s32 t_fine; /* calibration t_fine data */
} bmp280Calib;
bmp280Calib bmp280Cal;
static u8 bmp280ID=0;
static bool isInit=false;
static s32 bmp280RawPressure=0;
static s32 bmp280RawTemperature=0;
static void bmp280GetPressure(void);
static void presssureFilter(float* in,float* out);
static float bmp280PressureToAltitude(float* pressure/*, float* groundPressure, float* groundTemp*/);
bool bmp280Init(void)
{
if (isInit)
return true;
IIC_Init(); /*初始化I2C*/
delay_ms(20);
bmp280ID=iicDevReadByte(BMP280_ADDR,BMP280_CHIP_ID); /* 读取bmp280 ID*/
if(bmp280ID==BMP280_DEFAULT_CHIP_ID)
printf("BMP280 ID IS: 0x%X\n",bmp280ID);
else
return false;
/* 读取校准数据 */
iicDevRead(BMP280_ADDR,BMP280_TEMPERATURE_CALIB_DIG_T1_LSB_REG,24,(u8 *)&bmp280Cal);
iicDevWriteByte(BMP280_ADDR,BMP280_CTRL_MEAS_REG,BMP280_MODE);
iicDevWriteByte(BMP280_ADDR,BMP280_CONFIG_REG,5<<2); /*配置IIR滤波*/
isInit=true;
return true;
}
static void bmp280GetPressure(void)
{
u8 data[BMP280_DATA_FRAME_SIZE];
// read data from sensor
iicDevRead(BMP280_ADDR,BMP280_PRESSURE_MSB_REG,BMP280_DATA_FRAME_SIZE,data);
bmp280RawPressure=(s32)((((uint32_t)(data[0]))<<12)|(((uint32_t)(data[1]))<<4)|((uint32_t)data[2]>>4));
bmp280RawTemperature=(s32)((((uint32_t)(data[3]))<<12)|(((uint32_t)(data[4]))<<4)|((uint32_t)data[5]>>4));
}
// Returns temperature in DegC, resolution is 0.01 DegC. Output value of "5123" equals 51.23 DegC
// t_fine carries fine temperature as global value
static s32 bmp280CompensateT(s32 adcT)
{
s32 var1,var2,T;
var1=((((adcT>>3)-((s32)bmp280Cal.dig_T1<<1)))*((s32)bmp280Cal.dig_T2))>>11;
var2=(((((adcT>>4)-((s32)bmp280Cal.dig_T1))*((adcT>>4)-((s32)bmp280Cal.dig_T1)))>>12)*((s32)bmp280Cal.dig_T3))>>14;
bmp280Cal.t_fine=var1+var2;
T=(bmp280Cal.t_fine*5+128)>>8;
return T;
}
// Returns pressure in Pa as unsigned 32 bit integer in Q24.8 format (24 integer bits and 8 fractional bits).
// Output value of "24674867" represents 24674867/256 = 96386.2 Pa = 963.862 hPa
static uint32_t bmp280CompensateP(s32 adcP)
{
int64_t var1,var2,p;
var1=((int64_t)bmp280Cal.t_fine)-128000;
var2=var1*var1*(int64_t)bmp280Cal.dig_P6;
var2=var2+((var1*(int64_t)bmp280Cal.dig_P5)<<17);
var2=var2+(((int64_t)bmp280Cal.dig_P4)<<35);
var1=((var1*var1*(int64_t)bmp280Cal.dig_P3)>>8)+((var1*(int64_t)bmp280Cal.dig_P2)<<12);
var1=(((((int64_t)1)<<47)+var1))*((int64_t)bmp280Cal.dig_P1)>>33;
if (var1==0)
return 0;
p=1048576-adcP;
p=(((p<<31)-var2)*3125)/var1;
var1=(((int64_t)bmp280Cal.dig_P9)*(p>>13)*(p>>13))>>25;
var2=(((int64_t)bmp280Cal.dig_P8)*p)>>19;
p=((p+var1+var2)>>8)+(((int64_t)bmp280Cal.dig_P7)<<4);
return(uint32_t)p;
}
#define FILTER_NUM 5
#define FILTER_A 0.1f
/*限幅平均滤波法*/
static void presssureFilter(float* in,float* out)
{
*out=*in;
}
void bmp280GetData(float* pressure,float* temperature,float* asl)
{
static float t;
static float p;
bmp280GetPressure();
t=bmp280CompensateT(bmp280RawTemperature)/100.0;
p=bmp280CompensateP(bmp280RawPressure)/25600.0;
*temperature=(float)t; /*单位度*/
presssureFilter(&p,pressure); /*滤波后平均出压力单位hPa*/
*asl=bmp280PressureToAltitude(pressure); /*转换成海拔*/
}
#define CONST_PF 0.1902630958 //(1/5.25588f) Pressure factor
#define FIX_TEMP 25 // Fixed Temperature. ASL is a function of pressure and temperature, but as the temperature changes so much (blow a little towards the flie and watch it drop 5 degrees) it corrupts the ASL estimates.
// TLDR: Adjusting for temp changes does more harm than good.
/*
* Converts pressure to altitude above sea level (ASL) in meters
*/
static float bmp280PressureToAltitude(float* pressure/*, float* groundPressure, float* groundTemp*/)
{
if (*pressure>0)
{
return((pow((1015.7f/ *pressure),CONST_PF)-1.0f)*(FIX_TEMP+273.15f))/0.0065f;
}
else
{
return 0;
}
}
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