Arduino I2C + 气压传感器LPS25H#

https://www.cnblogs.com/zlbg/p/4237201.html

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LPS25H是ST生产的MEMS数字气压传感器。主要特性有：

  • 测量范围：260 ~ 1260 hPa绝对气压

  • 分辨率：均方根1 Pa

  • 工作电压：1.7 ~ 3.6 V

  • 功耗：4μA（低分辨率模式）~25μA（高分辨率模式）

  • 数据刷新频率：1 ~ 25 Hz可选择

  • 接口：I2C，三线制/四线制SPI

  • 内置温度补偿

  • 内置24位ADC

  • 内置先入先出（FIFO）存储器

  • 封装：2.5 x 2.5 x 1.0 mm HCLGA-10L

管脚定义#

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  • VDD：电源，1.7~3.6V

  • GND：地

  • VDD_IO：IO口供电脚，电压小于等于VDD

  • GND_IO：IO口接地脚，需与GND相连

  • Reserved：与GND相连

  • CS：I2C接口（CS=1）选择，或SPI接口片选脚（CS=0）

  • SCL/SPC：I2C接口或SPI接口的时钟线，通过CS脚选择

  • SDA/SDI/SDIO：I2C接口或SPI接口的数据线

  • SA0/SDO：I2C接口地址选择脚，或者SPI接口的数据线

  • INT1：中断输出脚，可编程其触发条件，参见CTRL_REG4寄存器设置

与Arduino的连接#

因为传感器IC大多工作在3.3V附近，因此干脆用工作于3.3V/8MHz版本的Arduino Pro Mini进行调试，避免了用UNO时接口电平转换的麻烦。采用I2C接口进行通讯。未利用INT1和FIFO的功能。

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LPS25H　　Pro Mini 3.3V/8MHz

VDD <------> 3.3V

GND <------> GND

SCL <------> A5 (SCL)

SDA <------> A4 (SDA)

测试代码#

/*
    Barometer based on LPS25H sensor and Arduino Pro Mini(3.3V)
*/

#include <Wire.h>

#define ADDRESS_LPS25H 0x5D
#define CTRL_REG1 0x20
#define CTRL_REG2 0x21
#define PRESS_OUT_XL 0x28

byte buffer[5];

boolean ready = false;
int tempOut;
long presOut;
float tempVal;
float presVal;

void setup()
{
    Wire.begin();
    Serial.begin(9600);

    //power down the device (clean start)
    Wire.beginTransmission(ADDRESS_LPS25H);
    Wire.write(CTRL_REG1);
    Wire.write(0x00);
    Wire.endTransmission();

    //turn on the sensor, set the one-shot mode, and set the BDU bit
    Wire.beginTransmission(ADDRESS_LPS25H);
    Wire.write(CTRL_REG1);
    Wire.write(0x84);
    Wire.endTransmission();
}

void loop()
{
    //run one-shot measurement
    Wire.beginTransmission(ADDRESS_LPS25H);
    Wire.write(CTRL_REG2);
    Wire.write(0x01);
    Wire.endTransmission();

    //wait until the measurement is completed
    while (ready == false)
    {
        delay(5); //conversion time: ~37ms
        Wire.beginTransmission(ADDRESS_LPS25H);
        Wire.write(CTRL_REG2);
        Wire.endTransmission();
        Wire.requestFrom(ADDRESS_LPS25H, 1);
        if (Wire.read() == 0x00)
        {
            ready = true;
        }
        // Serial.println("waiting...");
    }

    //read the result
    Wire.beginTransmission(ADDRESS_LPS25H);
    Wire.write(PRESS_OUT_XL | 0x80); //read multiple bytes
    Wire.endTransmission();

    Wire.requestFrom(ADDRESS_LPS25H, 5);
    if (Wire.available() >= 5)
    {
        for (int i = 0; i < 5; i++)
        {
            buffer[i] = Wire.read();
        }
    }
    ready = false;

    //calculation
    presOut = (long(buffer[2]) << 16) | (long(buffer[1]) << 8) | long(buffer[0]);
    presOut = (presOut << 8) >> 8; //PRESS_OUT_H/_L/_XL and is represented as 2’s complement
    presVal = presOut/4096.0;

    tempOut = (buffer[4] << 8) | buffer[3];
    tempVal = 42.5 + tempOut/480.0;

    Serial.print(presVal); Serial.print(" hPa\t");
    Serial.print(tempVal); Serial.println(" `C");

    delay(2000);
}

MCU每隔两秒测量一次气压和温度数据，并通过串口打印结果。

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参考资料#

LPS25H - STMicroelectronics