实验目的
使用模拟i2c接口读取温湿度气压模块BME280数据
实验准备
- PSoc62™开发板
- 温湿度气压模块BME280
- 公母头杜邦线
板载资源
本次实验是通过模拟i2c时序的方式来进行通信，理论上可以有非常多的方式配置i2c引脚，不像硬件i2c那样芯片出厂引脚已经固定好，所以这里不再列举i2c的GPIO资源，采用模拟i2c的好处是比较容易移植
模块电路
GPIO引脚
MCU_ARD_SCL -> P8.0
MCU_ARD_SDA -> P8.1
模块连接图
右侧排母从上往下第1、2引脚分别对应SCL、SDA
实物连接图
依次连接BME280模块的VCC、GND、SDL、SDA引脚
使能i2c接口
在创建的RT-Thread串口工程中打开RT-Thread Settings，点击右边的箭头<<进入详细页，使用前先使能i2c1，其中，pin number和GPIO的对应关系：P8.0 : 8 x 8 = 64，P8.1 : 8 x 8 + 1 = 65
i2c-tool软件包
i2c-tool是一个很方便的i2c通信调试工具，它可以查看总线上挂载设备地址、对i2c设备进行读写操作，安装方法如下
BME280的设备地址可以通过查询的方式得到，如下图所示
查询BME280设备ID命令，0x76是BME280设备地址，0xd0是设备ID的寄存器地址；如果通信正常，按照手册描述设备ID应该是0x60
i2c read i2c1 0x76 0xd0
程序设计
readCalibrationData、calibration_T、calibration_P、calibration_H用于读取和校准BME280的数据
static unsigned long int hum_raw,temp_raw,pres_raw;
static rt_uint8_t data[8];
static signed long int t_fine;
static uint16_t dig_T1;
static int16_t dig_T2;
static int16_t dig_T3;
static uint16_t dig_P1;
static int16_t dig_P2;
static int16_t dig_P3;
static int16_t dig_P4;
static int16_t dig_P5;
static int16_t dig_P6;
static int16_t dig_P7;
static int16_t dig_P8;
static int16_t dig_P9;
static int8_t dig_H1;
static int16_t dig_H2;
static int8_t dig_H3;
static int16_t dig_H4;
static int16_t dig_H5;
static int8_t dig_H6;
static signed long int temp_cal;
static unsigned long int press_cal,hum_cal;
static double temp_act;
static double press_act;
static double hum_act;
static void readCalibrationData()
{
uint8_t data[32];
read_bme280_reg(0x88, data, 24);
read_bme280_reg(0xa1, data + 24, 1);
read_bme280_reg(0xe1, data + 25, 7);
dig_T1 = (data[1] << 8) | data[0];
dig_T2 = (data[3] << 8) | data[2];
dig_T3 = (data[5] << 8) | data[4];
dig_P1 = (data[7] << 8) | data[6];
dig_P2 = (data[9] << 8) | data[8];
dig_P3 = (data[11]<< 8) | data[10];
dig_P4 = (data[13]<< 8) | data[12];
dig_P5 = (data[15]<< 8) | data[14];
dig_P6 = (data[17]<< 8) | data[16];
dig_P7 = (data[19]<< 8) | data[18];
dig_P8 = (data[21]<< 8) | data[20];
dig_P9 = (data[23]<< 8) | data[22];
dig_H1 = data[24];
dig_H2 = (data[26]<< 8) | data[25];
dig_H3 = data[27];
dig_H4 = (data[28]<< 4) | (0x0F & data[29]);
dig_H5 = (data[30] << 4) | ((data[29] >> 4) & 0x0F);
dig_H6 = data[31];
}
static signed long int calibration_T(signed long int adc_T)
{
signed long int var1, var2, T;
var1 = ((((adc_T >> 3) - ((signed long int)dig_T1<<1))) * ((signed long int)dig_T2)) >> 11;
var2 = (((((adc_T >> 4) - ((signed long int)dig_T1)) * ((adc_T>>4) - ((signed long int)dig_T1))) >> 12) * ((signed long int)dig_T3)) >> 14;
t_fine = var1 + var2;
T = (t_fine * 5 + 128) >> 8;
return T;
}
static unsigned long int calibration_P(signed long int adc_P)
{
signed long int var1, var2;
unsigned long int P;
var1 = (((signed long int)t_fine)>>1) - (signed long int)64000;
var2 = (((var1>>2) * (var1>>2)) >> 11) * ((signed long int)dig_P6);
var2 = var2 + ((var1*((signed long int)dig_P5))<<1);
var2 = (var2>>2)+(((signed long int)dig_P4)<<16);
var1 = (((dig_P3 * (((var1>>2)*(var1>>2)) >> 13)) >>3) + ((((signed long int)dig_P2) * var1)>>1))>>18;
var1 = ((((32768+var1))*((signed long int)dig_P1))>>15);
if (var1 == 0)
{
return 0;
}
P = (((unsigned long int)(((signed long int)1048576)-adc_P)-(var2>>12)))*3125;
if(P<0x80000000)
{
P = (P << 1) / ((unsigned long int) var1);
}
else
{
P = (P / (unsigned long int)var1) * 2;
}
var1 = (((signed long int)dig_P9) * ((signed long int)(((P>>3) * (P>>3))>>13)))>>12;
var2 = (((signed long int)(P>>2)) * ((signed long int)dig_P8))>>13;
P = (unsigned long int)((signed long int)P + ((var1 + var2 + dig_P7) >> 4));
return P;
}
static unsigned long int calibration_H(signed long int adc_H)
{
signed long int v_x1;
v_x1 = (t_fine - ((signed long int)76800));
v_x1 = (((((adc_H << 14) -(((signed long int)dig_H4) << 20) - (((signed long int)dig_H5) * v_x1)) +
((signed long int)16384)) >> 15) * (((((((v_x1 * ((signed long int)dig_H6)) >> 10) *
(((v_x1 * ((signed long int)dig_H3)) >> 11) + ((signed long int) 32768))) >> 10) + (( signed long int)2097152)) *
((signed long int) dig_H2) + 8192) >> 14));
v_x1 = (v_x1 - (((((v_x1 >> 15) * (v_x1 >> 15)) >> 7) * ((signed long int)dig_H1)) >> 4));
v_x1 = (v_x1 < 0 ? 0 : v_x1);
v_x1 = (v_x1 > 419430400 ? 419430400 : v_x1);
return (unsigned long int)(v_x1 >> 12);
}
i2c读写接口封装
static int read_bme280_reg(rt_uint8_t reg_addr, rt_uint8_t *data, rt_uint8_t len)
{
struct rt_i2c_msg msgs[2];
msgs[0].addr = BME280_ADDR;
msgs[0].flags = RT_I2C_WR;
msgs[0].buf = ®_addr;
msgs[0].len = 1;
msgs[1].addr = BME280_ADDR;
msgs[1].flags = RT_I2C_RD;
msgs[1].buf = data;
msgs[1].len = len;
if (rt_i2c_transfer(i2c_bus, msgs, 2) == 2)
{
return RT_EOK;
}
else
return -RT_ERROR;
}
static int8_t write_bme280_reg(uint8_t reg, uint8_t *data, uint16_t len)
{
rt_uint8_t tmp = reg;
struct rt_i2c_msg msgs[2];
msgs[0].addr = BME280_ADDR; /* Slave address */
msgs[0].flags = RT_I2C_WR; /* Write flag */
msgs[0].buf = &tmp; /* Slave register address */
msgs[0].len = 1; /* Number of bytes sent */
msgs[1].addr = BME280_ADDR; /* Slave address */
msgs[1].flags = RT_I2C_WR | RT_I2C_NO_START; /* Read flag */
msgs[1].buf = data; /* Read data pointer */
msgs[1].len = len; /* Number of bytes read */
if (rt_i2c_transfer(i2c_bus, msgs, 2) != 2)
{
return -RT_ERROR;
}
return RT_EOK;
}
init_bme280用于初始化i2c设备
static int init_bme280(void)
{
i2c_bus = (struct rt_i2c_bus_device *) rt_device_find(BME280_I2C_BUS_NAME);
if (i2c_bus == RT_NULL)
{
rt_kprintf("can't find %s device!\n", BME280_I2C_BUS_NAME);
return RT_ERROR;
}
rt_uint8_t data;
int size = read_bme280_reg(0xD0, &data, 1);
rt_kprintf("bme280 device id : %x\n", data);
uint8_t osrs_t = 1; //Temperature oversampling x 1
uint8_t osrs_p = 1; //Pressure oversampling x 1
uint8_t osrs_h = 1; //Humidity oversampling x 1
uint8_t mode = 3; //Normal mode
uint8_t t_sb = 5; //Tstandby 1000ms
uint8_t filter = 0; //Filter off
uint8_t spi3w_en = 0; //3-wire SPI Disable
uint8_t ctrl_meas_reg = (osrs_t << 5) | (osrs_p << 2) | mode;
uint8_t config_reg = (t_sb << 5) | (filter << 2) | spi3w_en;
uint8_t ctrl_hum_reg = osrs_h;
write_bme280_reg(0xF2, &ctrl_hum_reg, 1);
write_bme280_reg(0xF4, &ctrl_meas_reg, 1);
write_bme280_reg(0xF5, &config_reg, 1);
readCalibrationData();
return RT_EOK;
}
整合起来的代码
#include <rtthread.h>
#include <rtdevice.h>
#include "drv_gpio.h"
#define LED_PIN GET_PIN(0, 1)
#define BME280_I2C_BUS_NAME "i2c1"
#define BME280_ADDR 0x76
static struct rt_i2c_bus_device *i2c_bus;
static rt_thread_t bme280_thread = RT_NULL;
static unsigned long int hum_raw,temp_raw,pres_raw;
static rt_uint8_t data[8];
static signed long int t_fine;
static uint16_t dig_T1;
static int16_t dig_T2;
static int16_t dig_T3;
static uint16_t dig_P1;
static int16_t dig_P2;
static int16_t dig_P3;
static int16_t dig_P4;
static int16_t dig_P5;
static int16_t dig_P6;
static int16_t dig_P7;
static int16_t dig_P8;
static int16_t dig_P9;
static int8_t dig_H1;
static int16_t dig_H2;
static int8_t dig_H3;
static int16_t dig_H4;
static int16_t dig_H5;
static int8_t dig_H6;
static signed long int temp_cal;
static unsigned long int press_cal,hum_cal;
static double temp_act;
static double press_act;
static double hum_act;
static signed long int calibration_T(signed long int adc_T)
{
signed long int var1, var2, T;
var1 = ((((adc_T >> 3) - ((signed long int)dig_T1<<1))) * ((signed long int)dig_T2)) >> 11;
var2 = (((((adc_T >> 4) - ((signed long int)dig_T1)) * ((adc_T>>4) - ((signed long int)dig_T1))) >> 12) * ((signed long int)dig_T3)) >> 14;
t_fine = var1 + var2;
T = (t_fine * 5 + 128) >> 8;
return T;
}
static unsigned long int calibration_P(signed long int adc_P)
{
signed long int var1, var2;
unsigned long int P;
var1 = (((signed long int)t_fine)>>1) - (signed long int)64000;
var2 = (((var1>>2) * (var1>>2)) >> 11) * ((signed long int)dig_P6);
var2 = var2 + ((var1*((signed long int)dig_P5))<<1);
var2 = (var2>>2)+(((signed long int)dig_P4)<<16);
var1 = (((dig_P3 * (((var1>>2)*(var1>>2)) >> 13)) >>3) + ((((signed long int)dig_P2) * var1)>>1))>>18;
var1 = ((((32768+var1))*((signed long int)dig_P1))>>15);
if (var1 == 0)
{
return 0;
}
P = (((unsigned long int)(((signed long int)1048576)-adc_P)-(var2>>12)))*3125;
if(P<0x80000000)
{
P = (P << 1) / ((unsigned long int) var1);
}
else
{
P = (P / (unsigned long int)var1) * 2;
}
var1 = (((signed long int)dig_P9) * ((signed long int)(((P>>3) * (P>>3))>>13)))>>12;
var2 = (((signed long int)(P>>2)) * ((signed long int)dig_P8))>>13;
P = (unsigned long int)((signed long int)P + ((var1 + var2 + dig_P7) >> 4));
return P;
}
static unsigned long int calibration_H(signed long int adc_H)
{
signed long int v_x1;
v_x1 = (t_fine - ((signed long int)76800));
v_x1 = (((((adc_H << 14) -(((signed long int)dig_H4) << 20) - (((signed long int)dig_H5) * v_x1)) +
((signed long int)16384)) >> 15) * (((((((v_x1 * ((signed long int)dig_H6)) >> 10) *
(((v_x1 * ((signed long int)dig_H3)) >> 11) + ((signed long int) 32768))) >> 10) + (( signed long int)2097152)) *
((signed long int) dig_H2) + 8192) >> 14));
v_x1 = (v_x1 - (((((v_x1 >> 15) * (v_x1 >> 15)) >> 7) * ((signed long int)dig_H1)) >> 4));
v_x1 = (v_x1 < 0 ? 0 : v_x1);
v_x1 = (v_x1 > 419430400 ? 419430400 : v_x1);
return (unsigned long int)(v_x1 >> 12);
}
static int read_bme280_reg(rt_uint8_t reg_addr, rt_uint8_t *data, rt_uint8_t len)
{
struct rt_i2c_msg msgs[2];
msgs[0].addr = BME280_ADDR;
msgs[0].flags = RT_I2C_WR;
msgs[0].buf = ®_addr;
msgs[0].len = 1;
msgs[1].addr = BME280_ADDR;
msgs[1].flags = RT_I2C_RD;
msgs[1].buf = data;
msgs[1].len = len;
if (rt_i2c_transfer(i2c_bus, msgs, 2) == 2)
{
return RT_EOK;
}
else
return -RT_ERROR;
}
static int8_t write_bme280_reg(uint8_t reg, uint8_t *data, uint16_t len)
{
rt_uint8_t tmp = reg;
struct rt_i2c_msg msgs[2];
msgs[0].addr = BME280_ADDR; /* Slave address */
msgs[0].flags = RT_I2C_WR; /* Write flag */
msgs[0].buf = &tmp; /* Slave register address */
msgs[0].len = 1; /* Number of bytes sent */
msgs[1].addr = BME280_ADDR; /* Slave address */
msgs[1].flags = RT_I2C_WR | RT_I2C_NO_START; /* Read flag */
msgs[1].buf = data; /* Read data pointer */
msgs[1].len = len; /* Number of bytes read */
if (rt_i2c_transfer(i2c_bus, msgs, 2) != 2)
{
return -RT_ERROR;
}
return RT_EOK;
}
static void readCalibrationData()
{
uint8_t data[32];
read_bme280_reg(0x88, data, 24);
read_bme280_reg(0xa1, data + 24, 1);
read_bme280_reg(0xe1, data + 25, 7);
dig_T1 = (data[1] << 8) | data[0];
dig_T2 = (data[3] << 8) | data[2];
dig_T3 = (data[5] << 8) | data[4];
dig_P1 = (data[7] << 8) | data[6];
dig_P2 = (data[9] << 8) | data[8];
dig_P3 = (data[11]<< 8) | data[10];
dig_P4 = (data[13]<< 8) | data[12];
dig_P5 = (data[15]<< 8) | data[14];
dig_P6 = (data[17]<< 8) | data[16];
dig_P7 = (data[19]<< 8) | data[18];
dig_P8 = (data[21]<< 8) | data[20];
dig_P9 = (data[23]<< 8) | data[22];
dig_H1 = data[24];
dig_H2 = (data[26]<< 8) | data[25];
dig_H3 = data[27];
dig_H4 = (data[28]<< 4) | (0x0F & data[29]);
dig_H5 = (data[30] << 4) | ((data[29] >> 4) & 0x0F);
dig_H6 = data[31];
}
static int init_bme280(void)
{
i2c_bus = (struct rt_i2c_bus_device *) rt_device_find(BME280_I2C_BUS_NAME);
if (i2c_bus == RT_NULL)
{
rt_kprintf("can't find %s device!\n", BME280_I2C_BUS_NAME);
return RT_ERROR;
}
rt_uint8_t data;
int size = read_bme280_reg(0xD0, &data, 1);
rt_kprintf("bme280 device id : %x\n", data);
uint8_t osrs_t = 1; //Temperature oversampling x 1
uint8_t osrs_p = 1; //Pressure oversampling x 1
uint8_t osrs_h = 1; //Humidity oversampling x 1
uint8_t mode = 3; //Normal mode
uint8_t t_sb = 5; //Tstandby 1000ms
uint8_t filter = 0; //Filter off
uint8_t spi3w_en = 0; //3-wire SPI Disable
uint8_t ctrl_meas_reg = (osrs_t << 5) | (osrs_p << 2) | mode;
uint8_t config_reg = (t_sb << 5) | (filter << 2) | spi3w_en;
uint8_t ctrl_hum_reg = osrs_h;
write_bme280_reg(0xF2, &ctrl_hum_reg, 1);
write_bme280_reg(0xF4, &ctrl_meas_reg, 1);
write_bme280_reg(0xF5, &config_reg, 1);
readCalibrationData();
return RT_EOK;
}
static void bme280_entry(void* paremeter)
{
init_bme280();
while(1)
{
read_bme280_reg(0xf7, data, 8);
pres_raw = (data[0] << 12) | (data[1] << 4) | (data[2] >> 4);
temp_raw = (data[3] << 12) | (data[4] << 4) | (data[5] >> 4);
hum_raw = (data[6] << 8) | data[7];
temp_cal = calibration_T(temp_raw);
press_cal = calibration_P(pres_raw);
hum_cal = calibration_H(hum_raw);
temp_act = (double)temp_cal / 100.0;
press_act = (double)press_cal;
hum_act = (double)hum_cal / 1024.0;
rt_kprintf("Temperature=%4dC, Humidity=%4d%, Pressure=%4dPa \r\n",(int)temp_act,(int)hum_act,(int)press_act);
rt_thread_mdelay(500);
}
}
int main(void)
{
bme280_thread = rt_thread_create("bme280", bme280_entry, RT_NULL, 1024, 16, 20);
if(bme280_thread != RT_NULL)
{
rt_thread_startup(bme280_thread);
}
rt_pin_mode(LED_PIN, PIN_MODE_OUTPUT);
for (;;)
{
rt_pin_write(LED_PIN, PIN_HIGH);
rt_thread_mdelay(500);
rt_pin_write(LED_PIN, PIN_LOW);
rt_thread_mdelay(500);
}
}
实验效果
运行效果如下，控制台终端间隔500ms打印当前环境的温度、湿度、气压数据
