本文介绍了如何在ESP8266 (RTOS 3.2) 上配置和驱动BMP280、BME280和BMP180大气压计传感器。内容包括传感器简介、基础环境设定、软件原理示意图、数据打印展示以及代码结构。通过I2C连接，实现了对三种传感器的兼容性程序，其中BMP280作为BMP180的升级版，增加了绝对精度。BME280则额外具备湿度检测功能。
大气压计BMP280简介
BMP280是一款博世的气压传感器，主要是测量环境大气压强的，量程是300hPa~1100hPa，这个什么概念，海平面气压，即标准大气压是1013.25hPa,海拔近似0，珠穆朗玛海拔8844米，大气压大约在304hPa，和市面上大气压计差不多，每1hPa换算成垂直高度8.43米，具体海拔和气压的关系图如下：
BMP280传感器从名称上看是停产了的BMP180(End of lifetime)的升级款,对比来看，BMP280在绝对精度上提升大约2~4倍，IO口电压BMP280已覆盖了1.2V的电压，适用性会更好些。
另外看手册BME280和BMP280除了增加检测湿度的功能外，其他操作是一样的，顺便把湿度的一起加上了，做了一个根据ID判断的兼容程序。
而BMP180的驱动相对简单，和BMP085相差不多，但与BME280或BMP280不通用，旧产品。
基础环境
- 硬件是esp8266+BMP280模块，通过I2C连接并通讯, 顺便测试了下BMP180；
- 软件方面是乐鑫带的RTOSv3.2，本次使用案例工程里I2C例程修改的；
- 博世官方的BME280、BMP280、BMP180驱动程序；
由于没有BME280模块测试，只是根据datasheet添加了读取湿度逻辑，没有实际测试，理论上是OK的。
软件原理示意图
- BMP280/BME280的Forced模式逻辑：
- BMP280/BME280的Normal 模式逻辑:
- BMP180的操作流程
数据打印效果
BMP280的打印，内容有识别到的IC型号，参考温度，大气压的数值(hPa)：
BME280：
未测
BMP180的数据打印,内容有识别到型号，温度，大气压数值(Pa)，已知的当前检验海拔重新校验标准大气压数值，当前参考的海拔高度：
传感器配置参数
- I2C地址用的7位地址0x77，我把SDO上拉了，如果下拉或悬空会是0x76:
#define BMX280_I2C_ADDR 0x77
- 基本我放在了i2c_task_bme280_bmp280_bmp180初始化函数里面，做了一些变量，作为方便可配置.
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 = 0; //Sleep mode
uint8_t t_sb = 7; //Tstandby 4000ms
uint8_t filter = 0; //Filter off
uint8_t spi3w_en = 0; //3-wire SPI Disable
- BMP180的配置简单，只要改下模式就可以：
static uint8_t bmp180_mode = BMP180_OSS_1TIMES_RATE;
代码结构
代码分成3部分的文件，主文件、BMXx80驱动文件、标准I2C协议封装文件：
- main.c
- BME280_BMP280_BMP180.c
- BME280_BMP280_BMP180.h
- my_iic.h
- my_iic.c
- main.c：
/* main
This example code is in the Public Domain (or CC0 licensed, at your option.)
Unless required by applicable law or agreed to in writing, this
software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
CONDITIONS OF ANY KIND, either express or implied.
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/queue.h"
#include "esp_log.h"
#include "esp_system.h"
#include "esp_err.h"
#include "driver/i2c.h"
#include "BME280_BMP280_BMP180.h"
void app_main(void)
{
//start i2c task
xTaskCreate(i2c_task_bme280_bmp280_bmp180, "i2c_task_bme280_bmp280_bmp180", 2048, NULL, 10, NULL);
}
- BME280_BMP280_BMP180.h:
/* BME280 BMP280 BMX180 example
This example code is in the Public Domain (or CC0 licensed, at your option.)
Unless required by applicable law or agreed to in writing, this
software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
CONDITIONS OF ANY KIND, either express or implied.
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/queue.h"
#include "esp_log.h"
#include "esp_system.h"
#include "esp_err.h"
#include "my_iic.h"
#define BMX280_I2C_ADDR 0x77
#define BMP180_CHIP_ID 0x55
#define BMP280_CHIP_ID 0x58
#define BME280_CHIP_ID 0x60
#define BMX280_RESET_VALUE 0xB6
#define BMP280_DIG_AC1_MSB_REG 0xAA
#define BMP280_DIG_T1_LSB_REG 0x88
#define BMP280_DIG_H1_LSB_REG 0xA1
#define BMP280_DIG_H2_LSB_REG 0xE1
#define BMX280_CHIPID_REG 0xD0 /*Chip ID Register */
#define BMX280_RESET_REG 0xE0 /*Softreset Register */
#define BME280_CTRLHUM_REG 0xF2 /*Ctrl Humidity Register */
#define BMX280_STATUS_REG 0xF3 /*Status Register */
#define BMX280_CTRLMEAS_REG 0xF4 /*Ctrl Measure Register */
#define BMX280_CONFIG_REG 0xF5 /*Configuration Register */
#define BMX280_PRESSURE_MSB_REG 0xF7 /*Pressure MSB Register */
#define BMX280_PRESSURE_LSB_REG 0xF8 /*Pressure LSB Register */
#define BMX280_PRESSURE_XLSB_REG 0xF9 /*Pressure XLSB Register */
#define BMX280_TEMPERATURE_MSB_REG 0xFA /*Temperature MSB Reg */
#define BMX280_TEMPERATURE_LSB_REG 0xFB /*Temperature LSB Reg */
#define BMX280_TEMPERATURE_XLSB_REG 0xFC /*Temperature XLSB Reg */
#define BMP180_OSS_1TIMES_RATE 0 /* wait 4.5ms */
#define BMP180_OSS_2TIMES_RATE 1 /* wait 7.5ms */
#define BMP180_OSS_4TIMES_RATE 2 /* wait 13.5ms */
#define BMP180_OSS_8TIMES_RATE 3 /* wait 25.5ms */
#define BMP180_START_CONVERSION 1<<5
#define BMP180_READ_TEMPERATURE 0x0e
#define BMP180_READ_PRESSURE 0x14
#define BMP180_DATA_MSB_REG 0xF6 /* MSB Reg */
#define BMP180_DATA_LSB_REG 0xF7 /* LSB Reg */
#define BMP180_DATA_XLSB_REG 0xF8 /* XLSB Reg */
void i2c_task_bme280_bmp280_bmp180(void *arg);
- BME280_BMP280_BMP180.c:
/* BME280 BMP280 BMX180 example
This example code is in the Public Domain (or CC0 licensed, at your option.)
Unless required by applicable law or agreed to in writing, this
software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
CONDITIONS OF ANY KIND, either express or implied.
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
#include "BME280_BMP280_BMP180.h"
static const char *TAG = "BME280_BMP280_BMP180";
/**
* code auto select ic
* 0->BMP280
* 1->BME280
* 2->BMP180
*/
static uint8_t sensor_type =0;
static uint8_t bmp180_mode =BMP180_OSS_1TIMES_RATE;
static unsigned long int hum_raw, temp_raw, pres_raw;
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 int16_t dig_ac1;
static int16_t dig_ac2;
static int16_t dig_ac3;
static uint16_t dig_ac4;
static uint16_t dig_ac5;
static uint16_t dig_ac6;
static int16_t dig_b1;
static int16_t dig_b2;
static int16_t dig_mb;
static int16_t dig_mc;
static int16_t dig_md;
static int32_t dig_b5;
/* 软复位芯片 */
static void chip_reset(i2c_port_t i2c_num)
{
uint8_t rbuf = BMX280_RESET_VALUE;
ESP_ERROR_CHECK(i2c_m_write(i2c_num,BMX280_RESET_REG, &rbuf, 1));
vTaskDelay(100 / portTICK_RATE_MS);
}
/**
*
*/
static void readTrim(i2c_port_t i2c_num)
{
uint8_t data[32]= {0};
if(sensor_type==2) //select BMP180
{
ESP_ERROR_CHECK(i2c_m_read(i2c_num, BMP280_DIG_AC1_MSB_REG, &data[0], 22));
dig_ac1 = (data[0] << 8) | data[1];
dig_ac2 = (data[2] << 8) | data[3];
dig_ac3 = (data[4] << 8) | data[5];
dig_ac4 = (data[6] << 8) | data[7];
dig_ac5 = (data[8] << 8) | data[9];
dig_ac6 = (data[10] << 8) | data[11];
dig_b1 = (data[12] << 8) | data[13];
dig_b2 = (data[14] << 8) | data[15];
dig_mb = (data[16] << 8) | data[17];
dig_mc = (data[18] << 8) | data[19];
dig_md = (data[20] << 8) | data[21];
}
else //select BMP280 or BME280
{
ESP_ERROR_CHECK(i2c_m_read(i2c_num, BMP280_DIG_T1_LSB_REG, &data[0], 24));
if (sensor_type == 1)
{
ESP_ERROR_CHECK(i2c_m_read(i2c_num, BMP280_DIG_H1_LSB_REG, &data[24], 1));
ESP_ERROR_CHECK(i2c_m_read(i2c_num, BMP280_DIG_H2_LSB_REG, &data[25], 7));
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];
}
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];
}
}
/** @brief init bme(p)280 chip 此处主要是启动芯片和做兼容判断
* BME280多了湿度参数，处理数据时需要加上
*/
static esp_err_t bme280_bmp280_init(i2c_port_t i2c_num)
{
uint8_t rbuf;
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 = 0; //Sleep mode
uint8_t t_sb = 7; //Tstandby 4000ms
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;
i2c_addr = BMX280_I2C_ADDR;
vTaskDelay(100 / portTICK_RATE_MS);
i2c_master_init();
/* 读芯片ID，做BME280和BMP280的兼容*/
ESP_ERROR_CHECK(i2c_m_read(i2c_num, BMX280_CHIPID_REG, &rbuf, 1)); //id
if (rbuf == BMP280_CHIP_ID)
{
sensor_type = 0;
ESP_LOGI(TAG, "Get BMP280 sensor...\n");
}
else if (rbuf == BME280_CHIP_ID)
{
sensor_type = 1;
ESP_LOGI(TAG, "Get BME280 sensor...\n");
}
else if (rbuf == BMP180_CHIP_ID)
{
sensor_type = 2;
ESP_LOGI(TAG, "Get BMP180 sensor...\n");
}
else
{
ESP_LOGE(TAG, "No chip id, Get fail sensor.....\n");
}
readTrim(i2c_num);
chip_reset(i2c_num);
/*手册提到只要2ms就可以启动，可根据时间情况加减 */
vTaskDelay(4 / portTICK_RATE_MS);
if (sensor_type == 1 ) //select BME280
{
ESP_ERROR_CHECK(i2c_m_write(i2c_num,BME280_CTRLHUM_REG, &ctrl_hum_reg, 1));
}
if(sensor_type < 2 ) //select BMP280 or BME280
{
ESP_ERROR_CHECK(i2c_m_write(i2c_num,BMX280_CTRLMEAS_REG, &ctrl_meas_reg, 1));
ESP_ERROR_CHECK(i2c_m_write(i2c_num,BMX280_CONFIG_REG, &config_reg, 1));
/* 解决开机第一次数据不稳的问题 */
vTaskDelay(2000 / portTICK_RATE_MS);
}
return ESP_OK;
}
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 void readData(i2c_port_t i2c_num)
{
uint8_t data[8];
if (sensor_type == 1 )
{
ESP_ERROR_CHECK(i2c_m_read(I2C_EXAMPLE_MASTER_NUM, BMX280_PRESSURE_MSB_REG, &data[0], 8));
hum_raw = (data[6] << 8) | data[7];
}
else
{
ESP_ERROR_CHECK(i2c_m_read(I2C_EXAMPLE_MASTER_NUM, BMX280_PRESSURE_MSB_REG, &data[0], 6));
}
pres_raw = (data[0] << 12) | (data[1] << 4) | (data[2] >> 4);
temp_raw = (data[3] << 12) | (data[4] << 4) | (data[5] >> 4);
}
/* read uncompensated temperature value */
static uint16_t readUT(i2c_port_t i2c_num)
{
uint8_t buf[2]= {0};
//buf[0] = BMP180_READ_TEMPERATURE|BMP180_START_CONVERSION|(bmp180_mode<<6);
buf[0] =0x2e;
ESP_ERROR_CHECK(i2c_m_write(i2c_num, BMX280_CTRLMEAS_REG, &buf[0], 1));
vTaskDelay(10 / portTICK_RATE_MS);
ESP_ERROR_CHECK(i2c_m_read(i2c_num, BMP180_DATA_MSB_REG, buf, 2));
return (buf[0]<<8|buf[1]);
}
/* read uncompensated pressure value */
static int32_t readUP(i2c_port_t i2c_num)
{
uint8_t buf[3]= {0};
int32_t wait_time = 40;
int32_t ret = 0;
if(bmp180_mode ==0)
{
wait_time=10;
}
else if(bmp180_mode ==1)
{
wait_time=20;
}
else if(bmp180_mode ==2)
{
wait_time=30;
}
else if(bmp180_mode ==3)
{
wait_time=40;
}
buf[0] = BMP180_READ_PRESSURE | BMP180_START_CONVERSION | (bmp180_mode<<6);
ESP_ERROR_CHECK(i2c_m_write(i2c_num, BMX280_CTRLMEAS_REG, &buf[0], 1));
vTaskDelay(wait_time / portTICK_RATE_MS);
ESP_ERROR_CHECK(i2c_m_read(i2c_num, BMP180_DATA_MSB_REG, buf, 3));
ret = (buf[0]<<16|buf[1]<<8|buf[0])>>(8-bmp180_mode);
return ret;
}
int32_t computeB5(int32_t ut)
{
int32_t x1, x2;
x1 = (((long)ut - (long)dig_ac6)*(long)dig_ac5) >> 15;
x2 = ((long)dig_mc << 11)/(x1 + dig_md);
return x1 + x2;
}
// Calculate temperature in deg C
static float calculateTrueTemperature(void)
{
float temp;
int32_t ut;
ut = readUT(I2C_EXAMPLE_MASTER_NUM);
dig_b5 = computeB5(ut);
temp = ((dig_b5 + 8)>>4);
temp /= 10;
return temp;
}
// Calculate pressure given up
// calibration values must be known
// b5 is also required so bmp085GetTemperature(...) must be called first.
// Value returned will be pressure in units of Pa.
static int32_t calculateTruePressure(void)
{
int32_t up, x1, x2, x3, b3, b6, p;
uint32_t b4, b7;
up = readUP(I2C_EXAMPLE_MASTER_NUM);
b6 = dig_b5 - 4000;
// Calculate B3
x1 = ((int)dig_b2 * (b6 * b6)>>12)>>11;
x2 = ((int)dig_ac2 * b6)>>11;
x3 = x1 + x2;
b3 = (((((int)dig_ac1)*4 + x3)<<bmp180_mode) + 2)>>2;
// Calculate B4
x1 = ((int)dig_ac3 * b6)>>13;
x2 = ((int)dig_b1 * ((b6 * b6)>>12))>>16;
x3 = ((x1 + x2) + 2)>>2;
b4 = ((unsigned int)dig_ac4 * (unsigned long)(x3 + 32768))>>15;
b7 = (((unsigned int)up - b3) * (unsigned int)(50000>>bmp180_mode));
if (b7 < 0x80000000)
p = (b7<<1)/b4;
else
p = (b7/b4)<<1;
x1 = (p>>8) * (p>>8);
x1 = (x1 * 3038)>>16;
x2 = (-7357 * p)>>16;
p += (x1 + x2 + 3791)>>4;
return p;
}
int32_t calcSealevelPressure(float altitude_meters)
{
float pressure = calculateTruePressure();
return (int32_t)(pressure / pow(1.0-altitude_meters/44330, 5.255));
}
float calcAltitude(int32_t pressure)
{
float A = (float)pressure/101325.0f;
float B = 1.0f/5.25588f;
float C = pow(A,B);
C = 1.0f - C;
C *= 44330.0f;
return C;
}
void i2c_task_bme280_bmp280_bmp180(void *arg)
{
uint8_t rbuf;
double temp_act = 0.0, press_act = 0.0, hum_act = 0.0;
signed long int temp_cal;
unsigned long int press_cal = 0;
unsigned long int hum_cal = 0;
int32_t pressure;
int32_t atm = 0; // "standard atmosphere"
float altitude = 0; //Uncompensated caculation - in Meters
//int32_t temp_udata;
float temp_fdata;
/* For print flaot data*/
int32_t for_print_temp,for_print_temp1;
bme280_bmp280_init(I2C_EXAMPLE_MASTER_NUM);
while(1)
{
if(sensor_type <2) //select BMP280 or BME280
{
// Set forced mode again and again.
ESP_ERROR_CHECK(i2c_m_read(I2C_EXAMPLE_MASTER_NUM, BMX280_CTRLMEAS_REG, &rbuf, 1)); //status
vTaskDelay(4 / portTICK_RATE_MS);
rbuf &= (~0x03);
rbuf &= 0xff;
rbuf |= 0x1;
// write to Forced mode
ESP_ERROR_CHECK(i2c_m_write(I2C_EXAMPLE_MASTER_NUM, BMX280_CTRLMEAS_REG, &rbuf, 1));
vTaskDelay(20 / portTICK_RATE_MS);
//status 不为0时，可能数据没有准备好，或数据不稳定
ESP_ERROR_CHECK(i2c_m_read(I2C_EXAMPLE_MASTER_NUM,BMX280_STATUS_REG, &rbuf, 1));
if (rbuf != 0)
{
ESP_LOGE(TAG, "Data not ready.. skip [status =0x%02x]\n", rbuf);
vTaskDelay(30000 / portTICK_RATE_MS);
}
else
{
readData(I2C_EXAMPLE_MASTER_NUM);
temp_cal = calibration_T(temp_raw);
press_cal = calibration_P(pres_raw);
temp_act = (double)temp_cal / 100.0;
press_act = (double)press_cal / 100.0;
for_print_temp = (int)temp_act;
for_print_temp1 = (int)press_act;
ESP_LOGI(TAG, "TEMP : %d.%d°C PRESS : %d.%dhPa ",
for_print_temp,(int)((temp_act-for_print_temp)*100),
for_print_temp1, (int)((press_act-for_print_temp1)*100));
if (sensor_type == 1 ) //BME280
{
hum_cal = calibration_H(hum_raw);
hum_act = (double)hum_cal / 1024.0;
for_print_temp = (int)hum_act;
ESP_LOGI(TAG,"HUM : %d.%d%%\n",for_print_temp, (int)((hum_act-for_print_temp)*100));
}
else //BMP280
{
//ESP_LOGI(TAG, " \n");
}
vTaskDelay(60000 / portTICK_RATE_MS);
}
}
else //select BMP180
{
temp_fdata = calculateTrueTemperature();
pressure = calculateTruePressure();
atm = calcSealevelPressure(200.0f);//200 meters's pressure
altitude = calcAltitude(pressure);
for_print_temp = (int)temp_fdata;
ESP_LOGI(TAG,"temperature : %d.%dC\n",for_print_temp, (int)((temp_fdata - for_print_temp)*100));
ESP_LOGI(TAG,"pressure : %dPa\n",pressure);
ESP_LOGI(TAG,"If the altitude of this place is 200 meters，standard atmosphere is %dPa \n",atm);
for_print_temp = (int)altitude;
ESP_LOGI(TAG,"altitude: %d.%dm\n",for_print_temp, (int)((altitude - for_print_temp)*100));
vTaskDelay(5000 / portTICK_RATE_MS);
}
}
i2c_driver_delete(I2C_EXAMPLE_MASTER_NUM);
}
- my_iic.h:
/* I2C example
This example code is in the Public Domain (or CC0 licensed, at your option.)
Unless required by applicable law or agreed to in writing, this
software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
CONDITIONS OF ANY KIND, either express or implied.
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "driver/i2c.h"
/**
* TEST CODE BRIEF
*
* This example will show you how to use I2C module by running two tasks on i2c bus:
*
* - read external i2c sensor, here we use a BME280 & BMP280 sensor for instance.
* - Use one I2C port(master mode) to read or write the other I2C port(slave mode) on one ESP8266 chip.
*
* Pin assignment:
*
* - master:
* GPIO14 is assigned as the data signal of i2c master port
* GPIO2 is assigned as the clock signal of i2c master port
*
* Connection:
*
* - connect sda/scl of sensor with GPIO14/GPIO2
* - no need to add external pull-up resistors, driver will enable internal pull-up resistors.
*
* Test items:
*
* - read the sensor data, if connected.
*/
#define I2C_EXAMPLE_MASTER_SCL_IO 2 /*!< gpio number for I2C master clock */
#define I2C_EXAMPLE_MASTER_SDA_IO 14 /*!< gpio number for I2C master data */
#define I2C_EXAMPLE_MASTER_NUM I2C_NUM_0 /*!< I2C port number for master dev */
#define I2C_EXAMPLE_MASTER_TX_BUF_DISABLE 0 /*!< I2C master do not need buffer */
#define I2C_EXAMPLE_MASTER_RX_BUF_DISABLE 0 /*!< I2C master do not need buffer */
#define WRITE_BIT I2C_MASTER_WRITE /*!< I2C master write */
#define READ_BIT I2C_MASTER_READ /*!< I2C master read */
#define ACK_CHECK_EN 0x1 /*!< I2C master will check ack from slave*/
#define ACK_CHECK_DIS 0x0 /*!< I2C master will not check ack from slave */
#define ACK_VAL 0x0 /*!< I2C ack value */
#define NACK_VAL 0x1 /*!< I2C nack value */
#define LAST_NACK_VAL 0x2 /*!< I2C last_nack value */
uint8_t i2c_addr;
esp_err_t i2c_master_init();
esp_err_t i2c_m_write(i2c_port_t i2c_num, uint8_t reg_address, uint8_t *data, size_t data_len);
esp_err_t i2c_m_read(i2c_port_t i2c_num, uint8_t reg_address, uint8_t *data, size_t data_len);
- my_iic.c:
/* BMP280&BME280 sensor pressure example
This example code is in the Public Domain (or CC0 licensed, at your option.)
Unless required by applicable law or agreed to in writing, this
software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
CONDITIONS OF ANY KIND, either express or implied.
*/
#include "my_iic.h"
/**
* @brief i2c master initialization
*/
esp_err_t i2c_master_init()
{
int i2c_master_port = I2C_EXAMPLE_MASTER_NUM;
i2c_config_t conf;
conf.mode = I2C_MODE_MASTER;
conf.sda_io_num = I2C_EXAMPLE_MASTER_SDA_IO;
conf.sda_pullup_en = 0;
conf.scl_io_num = I2C_EXAMPLE_MASTER_SCL_IO;
conf.scl_pullup_en = 0;
ESP_ERROR_CHECK(i2c_driver_install(i2c_master_port, conf.mode));
ESP_ERROR_CHECK(i2c_param_config(i2c_master_port, &conf));
return ESP_OK;
}
/**
* @brief follow the NXP I2C protocal write
*
* 1. send data
* ___________________________________________________________________________________________________
* | start | slave_addr + wr_bit + ack | write reg_address + ack | write data_len byte + ack | stop |
* --------|---------------------------|-------------------------|----------------------------|------|
*
* @param i2c_num I2C port number
* @param reg_address slave reg address
* @param data data to send
* @param data_len data length
*
* @return
* - ESP_OK Success
* - ESP_ERR_INVALID_ARG Parameter error
* - ESP_FAIL Sending command error, slave doesn't ACK the transfer.
* - ESP_ERR_INVALID_STATE I2C driver not installed or not in master mode.
* - ESP_ERR_TIMEOUT Operation timeout because the bus is busy.
*/
esp_err_t i2c_m_write(i2c_port_t i2c_num, uint8_t reg_address, uint8_t *data, size_t data_len)
{
int ret;
i2c_cmd_handle_t cmd = i2c_cmd_link_create();
i2c_master_start(cmd);
i2c_master_write_byte(cmd, i2c_addr << 1 | WRITE_BIT, ACK_CHECK_EN);
i2c_master_write_byte(cmd, reg_address, ACK_CHECK_EN);
i2c_master_write(cmd, data, data_len, ACK_CHECK_EN);
i2c_master_stop(cmd);
ret = i2c_master_cmd_begin(i2c_num, cmd, 1000 / portTICK_RATE_MS);
i2c_cmd_link_delete(cmd);
return ret;
}
/**
* @brief follow the NXP I2C protocal read
*
* 1. send reg address
* ______________________________________________________________________
* | start | slave_addr + wr_bit + ack | write reg_address + ack | stop |
* --------|---------------------------|-------------------------|------|
*
* 2. read data
* ___________________________________________________________________________________
* | start | slave_addr + wr_bit + ack | read data_len byte + ack(last nack) | stop |
* --------|---------------------------|--------------------------------------|------|
*
* @param i2c_num I2C port number
* @param reg_address slave reg address
* @param data data to read
* @param data_len data length
*
* @return
* - ESP_OK Success
* - ESP_ERR_INVALID_ARG Parameter error
* - ESP_FAIL Sending command error, slave doesn't ACK the transfer.
* - ESP_ERR_INVALID_STATE I2C driver not installed or not in master mode.
* - ESP_ERR_TIMEOUT Operation timeout because the bus is busy.
*/
esp_err_t i2c_m_read(i2c_port_t i2c_num, uint8_t reg_address, uint8_t *data, size_t data_len)
{
int ret;
i2c_cmd_handle_t cmd = i2c_cmd_link_create();
i2c_master_start(cmd);
i2c_master_write_byte(cmd, i2c_addr << 1 | WRITE_BIT, ACK_CHECK_EN);
i2c_master_write_byte(cmd, reg_address, ACK_CHECK_EN);
i2c_master_stop(cmd);
ret = i2c_master_cmd_begin(i2c_num, cmd, 1000 / portTICK_RATE_MS);
i2c_cmd_link_delete(cmd);
if (ret != ESP_OK)
{
return ret;
}
cmd = i2c_cmd_link_create();
i2c_master_start(cmd);
i2c_master_write_byte(cmd, i2c_addr << 1 | READ_BIT, ACK_CHECK_EN);
i2c_master_read(cmd, data, data_len, LAST_NACK_VAL);
i2c_master_stop(cmd);
ret = i2c_master_cmd_begin(i2c_num, cmd, 1000 / portTICK_RATE_MS);
i2c_cmd_link_delete(cmd);
return ret;
}
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