1.0 简介
- BMP180气压计：气压传感器是用于测量气体的绝对压强的仪器。
- 有机发光二极管（OrganicLight-Emitting Diode，OLED），又称为有机电激光显示、有机发光半导体（OrganicElectroluminesence Display，OLED），是指有机半导体材料和发光材料在电场驱动下，通过载流子注入和复合导致发光的现象。本篇通过Arduino 01BMP180IIC采样得到气压和温度，再通过串口交互给Arduino 02，顺便 02的IIC通讯0.98寸OLED将气压和温度数据打印显示。
数字气压传感器的学习
高精度气压传感器一般是利用MEMS技术在单晶硅片上加工出真空腔体和惠斯登电桥，惠斯登电桥桥臂两端的输出电压与施加的压力成正比，经过温度补偿和校准后具有体积小，精度高，响应速度快，不受温度变化影响的特点。输出方式一般为模拟电压输出和数字信号输出两种，其中数字信号输出方式由于和单片机连接方便，是市场上的主流。
- 工作原理：
当被测气体的压力降低或升高时，这个薄膜变形带动顶针，同时该电阻器的阻值将会改变。电阻器的阻值发生变化。从传感元件取得0-5V的信号电压，经过A/D转换由数据采集器接受，然后数据采集器以适当的形式把结果传送给计算机。
- BMP180相关参数如下：
压力范围:300hPa - -1100hPa（海拔9000m - - 500m)电源电压:1.8v - - 3.6v (VIN), 1.62v3.6v(VDDD)LCC8封装:无铅陶瓷载体封装(LCC)
尺寸: 3.6mmx3.8x0.93mm
低功耗:5uA，在标准模式
高精度:低功耗模式下，分辨率为0.06hPa （0.5米)高线性模式下，分辨率为0.03hPa (0.25米)
含温度输出
I2C接口温度补偿
无铅，符合RoHs规范MSL 1反应时间:7.5ms待机电流:0.1uA无需外部时钟电路
2.0 实验材料
- Arduino Uno R3开发板两块
- BMP180气压计传感器
- 0.98寸OLED
- 八根公母线
- USB数据线
- 一台安装Arduino开发环境的电脑
3.0 实验步骤
3.1 根据原理图搭建电路
BMP180传感器为3.3V供电，采用IIC通讯其中信号输出端连接到Arduino 01弟弟的信号线SDA（uno 的A4也可以）和一根时钟线SCL（uno 的A5也可以）引脚上；Arduino 01弟弟与Arduino 02哥哥通过软串口9号和10号通讯，需对调，Arduino 02哥哥通过IIC与OLED显示器通讯，因此除了5V供电的两根线外，只需要一根信号线SDA（uno 的A4也可以）和一根时钟线SCL（uno 的A5也可以）就可以。
实验原理图：
实验接线图：
3.2 新建sketch，分别拷贝如下代码并进行保存编译上传
Arduino IDE代码所需U8g2lib库
Arduino 01弟弟代码：
/**************************************************************************************/ /**********************DFRobot.com*****************************/ /***write by Tom Riddler Jun.16.14***/ /***if you got any progream,please contact me terminaterfxy@hotmail.com***/ #include <SoftwareSerial.h> SoftwareSerial mySerial(9, 10); // RX, TX #include <Wire.h> #define BMP180ADD 0x77 // I2C address of BMP180 //write is (0xEE) read is (0xEF) unsigned char OSS; /**********************MSB LSB******/ int ac1; // 0xAA 0xAB int ac2; // 0xAC 0xAD int ac3; // 0xAE 0xAE unsigned int ac4; // 0xB0 0xB1 unsigned int ac5; // 0xB2 0xB3 unsigned int ac6; // 0xB4 0xB5 int b1; // 0xB6 0xB7 int b2; // 0xB8 0xB9 int mb; // 0xBA 0xBB int mc; // 0xBC 0xBD int md; // 0xBE 0xBF float temperature; int Temperature; double pressure; int Pressure; double pressure2; long b5; double altitude; int Altitude; int sensorA0 = 0; int sensorA1 = 0; int sensorA2 = 0; int sensorA3 = 0; int sensorA4 = 0; int sensorA5 = 0; void setup() { mySerial.begin(9600); Serial.begin(9600); Wire.begin(); OSS = 2; // Oversampling Setting 0: single 1: 2 times 2: 4 times 3: 8 times BMP180start(); } void loop() { calculate();//BMP180计算 delay(500); Temperature=temperature/1,Pressure=pressure/1,Altitude=altitude/1;//双精度浮点数转为整形输出 sensorA0 = analogRead(A0); sensorA1 = analogRead(A1); sensorA2 = analogRead(A2); sensorA3 = analogRead(A3); sensorA4 = analogRead(A4); sensorA5 = analogRead(A5); Serial.println("A0:" + String(Temperature) + ";A1:" + String(Pressure) + ";A2:" + String(Altitude) + ";A3:" + String(sensorA3) + ";A4:" + String(sensorA4) + ";A5:" + String(sensorA5)); mySerial.println("A0:" + String(Temperature) + ";A1:" + String(Pressure) + ";A2:" + String(Altitude) + ";A3:" + String(sensorA3) + ";A4:" + String(sensorA4) + ";A5:" + String(sensorA5)); show(); delay(1000); } /** calculate centure **/ void calculate() { temperature = bmp180GetTemperature(bmp180ReadUT()); temperature = temperature * 0.1; pressure = bmp180GetPressure(bmp180ReadUP())/1000; pressure2 = 1000*pressure / 101325; pressure2 = pow(pressure2, 0.19029496); altitude = 44330 * (1 - pressure2); //altitude = 44330*(1-(pressure/101325)^0.19029496); } /** print reslut **/ void show() { Serial.print("Temperature: "); Serial.print(temperature, 1); //10 hexadecimal Serial.println(" C"); Serial.print("Pressure: "); Serial.print(pressure, 0); //10 hexadecimal Serial.println(" Pa"); Serial.print("altitude:"); Serial.print(altitude); Serial.println("m"); } /**BMP180 satrt program**/ void BMP180start() { /*MSB*/ ac1 = bmp180ReadDate(0xAA); //get full data ac2 = bmp180ReadDate(0xAC); ac3 = bmp180ReadDate(0xAE); ac4 = bmp180ReadDate(0xB0); ac5 = bmp180ReadDate(0xB2); ac6 = bmp180ReadDate(0xB4); b1 = bmp180ReadDate(0xB6); b2 = bmp180ReadDate(0xB8); mb = bmp180ReadDate(0xBA); mc = bmp180ReadDate(0xBC); md = bmp180ReadDate(0xBE); } /***BMP180 temperature Calculate***/ short bmp180GetTemperature(unsigned int ut) { long x1, x2; x1 = (((long)ut - (long)ac6) * (long)ac5) >> 15; //x1=((ut-ac6)*ac5)/(2^15) x2 = ((long)mc << 11) / (x1 + md); //x2=(mc*2^11)/(x1+md) b5 = x1 + x2; //b5=x1+x2 return ((b5 + 8) >> 4); //t=(b5+8)/(2^4) } /***BMP180 pressure Calculate***/ long bmp180GetPressure(unsigned long up) { long x1, x2, x3, b3, b6, p; unsigned long b4, b7; b6 = b5 - 4000; x1 = (b2 * (b6 * b6) >> 12) >> 11; x2 = (ac2 * b6) >> 11; x3 = x1 + x2; b3 = (((((long)ac1) * 4 + x3) << OSS) + 2) >> 2; x1 = (ac3 * b6) >> 13; x2 = (b1 * ((b6 * b6) >> 12)) >> 16; x3 = ((x1 + x2) + 2) >> 2; b4 = (ac4 * (unsigned long)(x3 + 32768)) >> 15; b7 = ((unsigned long)(up - b3) * (50000 >> OSS)); 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; } /*** Read 1 bytes from the BMP180 ***/ int bmp180Read(unsigned char address) { unsigned char data; Wire.beginTransmission(BMP180ADD); Wire.write(address); Wire.endTransmission(); Wire.requestFrom(BMP180ADD, 1); while (!Wire.available()); return Wire.read(); } /*** Read 2 bytes from the BMP180 ***/ int bmp180ReadDate(unsigned char address) { unsigned char msb, lsb; Wire.beginTransmission(BMP180ADD); Wire.write(address); Wire.endTransmission(); Wire.requestFrom(BMP180ADD, 2); while (Wire.available() < 2); msb = Wire.read(); lsb = Wire.read(); return (int) msb << 8 | lsb; } /*** read uncompensated temperature value ***/ unsigned int bmp180ReadUT() { unsigned int ut; Wire.beginTransmission(BMP180ADD); Wire.write(0xF4); // Write 0x2E into Register 0xF4 Wire.write(0x2E); // This requests a temperature reading Wire.endTransmission(); delay(5); // Wait at least 4.5ms ut = bmp180ReadDate(0xF6); // read MSB from 0xF6 read LSB from (16 bit) return ut; } /*** Read uncompensated pressure value from BMP180 ***/ unsigned long bmp180ReadUP() { unsigned char msb, lsb, xlsb; unsigned long up = 0; Wire.beginTransmission(BMP180ADD); Wire.write(0xF4); // Write 0x34+(OSS<<6) into register 0xF4 Wire.write(0x34 + (OSS << 6)); // 0x34+oss*64 Wire.endTransmission(); delay(2 + (3 << OSS)); // Wait for conversion, delay time dependent on OSS Wire.beginTransmission(BMP180ADD); Wire.write(0xF6); // Read register 0xF6 (MSB), 0xF7 (LSB), and 0xF8 (XLSB) Wire.endTransmission(); Wire.requestFrom(BMP180ADD, 3); while (Wire.available() < 3); // Wait for data to become available msb = Wire.read(); lsb = Wire.read(); xlsb = Wire.read(); up = (((unsigned long) msb << 16) | ((unsigned long) lsb << 8) | (unsigned long) xlsb) >> (8 - OSS); //16 to 19 bit return up; }
Arduino 02哥哥代码：
#include <U8g2lib.h> #include <Wire.h> U8G2_SSD1306_128X64_NONAME_1_HW_I2C u8g2(U8G2_R0, U8X8_PIN_NONE); #include <SoftwareSerial.h> SoftwareSerial mySerial(9, 10); // RX, TX String message_c; const char* message; int sensorA0; int sensorA1; int sensorA2; int sensorA3; int sensorA4; int sensorA5; void setup() { Serial.begin(9600); while (Serial.read() >= 0) {} //清空串口0缓存 mySerial.begin(9600); mySerial.listen(); u8g2.begin(); u8g2.enableUTF8Print(); } void loop() { if (mySerial.available()) { String message_c = mySerial.readString(); //串口1接收字符串 // Serial.print(message_c); //串口0打印串口1接收的字符串 // Serial.println(message_c.length()); //串口0打印串口1接收的字符串长度 message = message_c.c_str(); //由于sscanf只能识别const char*类型字符串，将String类型字符串转成const char*类型 sscanf(message, "A0:%d;A1:%d;A2:%d;A3:%d;A4:%d;A5:%d", &sensorA0, &sensorA1, &sensorA2, &sensorA3, &sensorA4, &sensorA5); //串口1接收字符串格式为435;25.25 Serial.print("sensorA0="); Serial.print(sensorA0); Serial.print(", sensorA1="); Serial.print(sensorA1); Serial.print(", sensorA2="); Serial.print(sensorA2); Serial.print(", sensorA3="); Serial.print(sensorA3); Serial.print(", sensorA4="); Serial.print(sensorA4); Serial.print(", sensorA5="); Serial.println(sensorA5); // while (mySerial.read() >= 0) {}; //清空串口1缓存，保证字符串的长度稳定 } u8g2.firstPage(); do { page1(); } while (u8g2.nextPage()); delay(100); } void page1() { u8g2.setFont(u8g2_font_timB10_tf); u8g2.setFontPosTop(); u8g2.setCursor(2, 10); u8g2.print("A0:"); u8g2.setCursor(25, 10); u8g2.print(sensorA0); u8g2.setCursor(45, 10); u8g2.print("°C"); u8g2.setCursor(2, 30); u8g2.print("A1:"); u8g2.setCursor(25, 30); u8g2.print(sensorA1); u8g2.setCursor(45, 30); u8g2.print("Kpa"); u8g2.setCursor(2, 50); u8g2.print("A2:"); u8g2.setCursor(25, 50); u8g2.print(sensorA2); u8g2.setCursor(45, 50); u8g2.print("m"); u8g2.setCursor(77, 10); u8g2.print("A3:"); u8g2.setCursor(100, 10); u8g2.print(sensorA3); u8g2.setCursor(77, 30); u8g2.print("A4:"); u8g2.setCursor(100, 30); u8g2.print(sensorA4); u8g2.setCursor(77, 50); u8g2.print("A5:"); u8g2.setCursor(100, 50); u8g2.print(sensorA5); u8g2.drawVLine(75, 4, 60); u8g2.drawHLine(1, 25, 127); u8g2.drawHLine(1, 45, 127); u8g2.drawFrame(1, 1, 127, 63); }
3.3 实验现象
打开窗口监视，观察OLED显示屏和串口的数据是否一致 ，然后手动捂热BPM180 ，观察其两者动态变化 😃😃😃
视频演示
BMP180兄弟互联
4.0 总结
- 本篇通过Arduino 01弟弟通过IIC与BMP180通讯采样得到气压和温度，再通过串口交互给Arduino 02哥哥，顺便 Arduino 02哥哥的IIC通讯0.98寸OLED将气压和温度数据打印显示。。难度综合性强，值得新手一试！！！😃😃😃
- 在以后的博文中我们将学会用arduino常用传感器和执行器，从而实现对外部世界进行感知，充分认识这个有机与无机的环境，科学地合理地进行创作和发挥效益，然后为人类社会发展贡献一点微薄之力
