一、树莓派引脚图

二、bmp280简介

1、

2、模块引脚

三、打开i2c

1、

2、

四、代码实现  bmp280.C

#include <stdio.h>
#include <stdlib.h>
#include <wiringPi.h>
#include <wiringPiI2C.h>

unsigned short dig_t1, dig_p1;
signed short dig_t2, dig_t3, dig_p2, dig_p3, dig_p4;
signed short dig_p5, dig_p6, dig_p7, dig_p8, dig_p9;
float temp, pres, var1, var2;
int pres_int = 0, bmp280_flag = -1;
unsigned short msb, lsb, xlsb, pres_h = 0, pres_l = 0, pres_flo = 0;

int i2c_fd;

int Raspi_BMP280_Init()
{
	//system("sudo ulimit -n 4096");
	wiringPiSetup();
	i2c_fd = wiringPiI2CSetup(0x76);
	if (wiringPiI2CReadReg8(i2c_fd, 0xd0) == 0x58)
	{
		system("sudo i2cset -y 1 0x76 0xff 0xf4");
		dig_t1 = (wiringPiI2CReadReg8(i2c_fd, 0x89) << 8)
			| wiringPiI2CReadReg8(i2c_fd, 0x88);

		dig_t2 = (wiringPiI2CReadReg8(i2c_fd, 0x8b) << 8)
			| wiringPiI2CReadReg8(i2c_fd, 0x8a);

		dig_t3 = (wiringPiI2CReadReg8(i2c_fd, 0x8d) << 8)
			| wiringPiI2CReadReg8(i2c_fd, 0x8c);

		dig_p1 = (wiringPiI2CReadReg8(i2c_fd, 0x8f) << 8)
			| wiringPiI2CReadReg8(i2c_fd, 0x8e);

		dig_p2 = (wiringPiI2CReadReg8(i2c_fd, 0x91) << 8)
			| wiringPiI2CReadReg8(i2c_fd, 0x90);

		dig_p3 = (wiringPiI2CReadReg8(i2c_fd, 0x93) << 8)
			| wiringPiI2CReadReg8(i2c_fd, 0x92);
		dig_p4 = (wiringPiI2CReadReg8(i2c_fd, 0x95) << 8)
			| wiringPiI2CReadReg8(i2c_fd, 0x94);
		dig_p5 = (wiringPiI2CReadReg8(i2c_fd, 0x97) << 8)
			| wiringPiI2CReadReg8(i2c_fd, 0x96);
		dig_p6 = (wiringPiI2CReadReg8(i2c_fd, 0x99) << 8)
			| wiringPiI2CReadReg8(i2c_fd, 0x98);
		dig_p7 = (wiringPiI2CReadReg8(i2c_fd, 0x9b) << 8)
			| wiringPiI2CReadReg8(i2c_fd, 0x9a);
		dig_p8 = (wiringPiI2CReadReg8(i2c_fd, 0x9d) << 8)
			| wiringPiI2CReadReg8(i2c_fd, 0x9c);
		dig_p9 = (wiringPiI2CReadReg8(i2c_fd, 0x9f) << 8)
			| wiringPiI2CReadReg8(i2c_fd, 0x9e);
		return 0;
	}
	return -1;
}

float Raspi_BMP280_Read_Pressure()
{
	msb = wiringPiI2CReadReg8(i2c_fd, 0xf7);
	lsb = wiringPiI2CReadReg8(i2c_fd, 0xf8);
	xlsb = wiringPiI2CReadReg8(i2c_fd, 0xf9);
	pres = (msb << 16 | lsb << 8 | xlsb) >> 4;

	msb = wiringPiI2CReadReg8(i2c_fd, 0xfa);
	lsb = wiringPiI2CReadReg8(i2c_fd, 0xfb);
	xlsb = wiringPiI2CReadReg8(i2c_fd, 0xfc);
	temp = (msb << 16 | lsb << 8 | xlsb) >> 4;

	var1 = (temp / 16384.0 - dig_t1 / 1024.0)*(dig_t2);
	var2 = ((temp / 131072.0 - dig_t1 / 8192.0)*(temp / 131072.0 - dig_t1 / 8192.0))*dig_t3;
	temp = var1 + var2;
	temp /= 5120.0;

	var1 = (temp / 2.0) - 64000.0;
	var2 = var1 * var1*(dig_p6) / 32768.0;
	var2 = var2 + var1 * (dig_p5)*2.0;
	var2 = (var2 / 4.0) + ((dig_p4)*65536.0);
	var1 = (dig_p3)*var1*var1 / 524288.0 + (dig_p2)*var1 / 524288.0;
	var1 = (1.0 + var1 / 32768.0)*(dig_p1);

	pres = 1048576.0 - pres;
	pres = (pres - (var2 / 4096.0))*6250.0 / var1;
	var1 = (dig_p9)*pres*pres / 2147483648.0;
	var2 = pres * (dig_p8) / 32768.0;
	pres = pres + (var1 + var2 + (dig_p7)) / 16.0;
	return pres;
}

int main()
{
	float pre;
	while (Raspi_BMP280_Init() != 0);
	while (1)
	{
		pre = Raspi_BMP280_Read_Pressure();
		printf("%.2f\n", pre);
	}
}

 

五、编译运行bmp280.c

1、编译

sudo gcc bmp280.c -o bmp280 -lwiringPi

2、运行

./bmp280