一、硬件介绍
1、产品特点
空气质量评估板用于评估 Telaire 空气质量传感器，可支持 SM-PWM-01C 粉尘传感器，串行输出可以配置为通过 USB 连接将传感器数据发送到 PC，进行记录和分析等。
特性
Arduino 平台
保留的 SM-PWM-01C 传感器接口
保留的 T6713 二氧化碳传感器接口
保留的 T9602 温度和湿度传感器接口
支持蓝牙 BLE4.0 OSPF 模块
支持 128*64 OLED 屏幕
外部 USB 电源
参数 额定值
供电电源 5V DC
供电电流 1A
工作温度范围 0~60°
工作湿度范围 0~95%RH
输出电平(3V3) Low：0.8V Hight：2.7V
支持接口 I2C：T9602 温湿度传感器 UART：T6713 二氧化碳传感器 PWM：灰尘传感器 I2C：OLED屏幕模块
实物图
2、粉尘传感器
SM-PWM-01C是一款利用光学方法检测空气中粉尘浓度的传感器。在传感器中一个红外LED 和一个光接收器光轴相交，当带粉尘的气流通过交叉区域，产生折射光。光接收器检测到粉尘反射的红外LED光线，根据输出信号的强弱判断粉尘的浓度。粉尘传感器能检测像香烟颗粒大小的颗粒物与室内灰尘等大颗粒，通过输出PWM脉冲信号宽度来区分。
管脚 管脚定义
GND 地
P2 大颗粒粉尘的低脉冲输出P2
VCC 电源电压
P1 小颗粒粉尘的低脉冲输出P1
NC ——
3、OLED屏幕
0.96寸6针oled屏幕
主要参数
通信方式：lIC、SPI。 亮度、对比度可以通过程序指令控制。 OLED屏幕内部驱动芯片：SSD1306。
可根据后面焊接电阻R的选择，从而选择不同的通信方式（SPI / I2C）
引脚 定义
GND 电源负
VCC 电源正 3.3V-5V
SCL 时钟信号线
SDA 双向数据线
RES 复位
D/C 数据或命令切换
4、Arduino 兼容板（Ardunio UNO）
板载的MCU为8位微控制器 ATMEGA328P-PU
ATMEGA328P-PU 是高性能Atmel picoPower 8位AVR基于RISC的微控制器结合了32KB ISP闪存存储器,1024B EEPROM,2KB SRAM等；
二、环境搭建
1、下载Arduino IDE
2、下载相关例程
解压后工程文件目录
3、安装所需相关库
pinchangeint
Adafruit_SSD1306
三、程序代码分析
主要功能
1、传感器监测
T6700 CO2传感器：检测二氧化碳浓度；
T9602温湿度传感器：检测温度和湿度；
SM-PWM-01C粉尘传感器：检测PM2.5颗粒物浓度
2、输出方式
串口输出(USB模式)：通过串口向电脑发送数据；
OLED显示屏输出：在OLED(SSD1306)屏上显示相关数据；
代码结构分析
传感器部分：
getT6700data()：读取CO2浓度；
getT9602data()：读取温湿度；
CalculateDustValue()：计算粉尘浓度；
calcPM2()：粉尘传感器中断服务程序；
显示部分：
displaySetupScreen()：初始化显示；
displayReading()：显示传感器读数；
轮询显示：温度 → 湿度 → CO₂ → AQI 颜色（带 PM2.5 值）
由于只有粉尘传感器，所以只会显示 PM2.5值、AQI 颜色；
#define USB //enable or disable monitoring on serial output, alternate with display, 19200 baud
//#define OELCD_OP //enable or disable LCD Output, alternate with serial output
#define DustSensor true // true or false dependent upon if dust sensor present, true by default as we cannot handshake
#include "Wire.h"
#include <SPI.h>
#include <PinChangeInterrupt.h>
// Width Guide "---------------------"
#define SplashScreen "Telaire eval, v1.4"
char ScreenHeader[] = " Amphenol Sensors";
char ScreenFooter[] = " Telaire Technology";
#ifdef OELCD_OP
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include "OELCD.h"
#endif
#include "T9602.h"
#include "T6700.h"
#include "SM-PWM-01C.h"
byte error;
byte Connected = 0; // bit values define sensor presence B1 - T6700, B10 T9602 Temp, B100 T9602 Hum, B1000 Dust
byte data[6];
byte kk = 1;
unsigned int Offset = 0;
//_______________________________________________setup_________________________________
void setup()
{
#ifdef USB //output to PC through USB
Serial.begin(19200); // start serial for output
Serial.println(SplashScreen);
#endif
Wire.begin();
#ifdef OELCD_OP
// by default, we'll generate the high voltage from the 3.3v line internally
display.begin(SSD1306_SWITCHCAPVCC);
displaySetupScreen();
#endif
Wire.beginTransmission(ADDR_6700); // check if T6700 series is present
error = Wire.endTransmission();
if (error == 0)
{
#ifdef USB //output to PC through USB
Serial.println("T6700 Detected");
#endif
Connected = 1;
}
Wire.beginTransmission(ADDR_9602); // check if T9602 series is present
error = Wire.endTransmission();
if (error == 0)
{
#ifdef USB //output to PC through USB
Serial.println("T9602 Detected");
#endif
Connected = Connected + 6;
}
// assume Dust Sensor is present as we cannot handshake it
if (DustSensor) {
#ifdef USB //output to PC through USB
Serial.println("Dust Sensor Detected");
#endif
Connected = Connected + 8;
pinMode(PM2_IN_PIN, INPUT); //setup SWM PWM 01C Pins to work with pininterrupt algorithm
pinMode(PM2_OUT_PIN, OUTPUT);
// using the PinChangeInt library, attach the interrupts
// used to read the channels
attachPCINT(digitalPinToPCINT(PM2_IN_PIN), calcPM2, CHANGE);
}
#ifdef USB //output to PC through USB
if ((Connected & B00000001) == 1 ) {
Serial.print("CO2ppm");
Serial.print (",");
}
if ((Connected & B00000110) == 6 ) {
Serial.print("Temperature"); Serial.print (",");
Serial.print("Humidity"); Serial.print (",");
}
if ((Connected & B00001000) == 8 ) {
Serial.print("PM2_Value"); Serial.print (",");
Serial.print ("AQIColour");
}
Serial.println (" ");
#endif
#ifdef OELCD_OP
if ((Connected & B00000001) == 1 ) {
displayReading("", "CO2 Sensor", "", Offset);
delay(1000);
}
if ((Connected & B00000110) == 6 ) {
displayReading("", "T9602 Sensor", "", Offset);
delay(1000);
}
if ((Connected & B00001000) == 8 ) {
displayReading("", "Dust Sensor", "", Offset);
delay(1000);
}
#endif
}
//___________________________________________________loop______________________
void loop() {
if (millis() >= (samplerate + sampletime))
{
if ((Connected & B00000001) == 1 ) {
getT6700data();
}
if ((Connected & B00000110) == 6 ) {
getT9602data();
}
if ((Connected & B00001000) == 8 ) {
CalculateDustValue();
}
sampletime = millis(); //resets timer before printing output
#ifdef OELCD_OP
String SensorReading;
String AuxInfo;
String Units;
if (kk >= 5) {
kk = 1;
}
if (kk == 1) {
if ((Connected & B00000010) == 2 ) //is T9602 temp present?
{ SensorReading = String(temperature);
SensorReading.remove(4);
Units = char(247); Units += "C";
AuxInfo = "Temperature";
Offset = 10;
}
else {
kk++;
}
}
if (kk == 2) {
if ((Connected & B00000100) == 4 ) { //is T9602 hum present?
SensorReading = String(humidity);
SensorReading.remove(4);
Units = "%rH";
AuxInfo = char(32); AuxInfo += char(32);
AuxInfo += "Humidity";
Offset = 10;
}
else {
kk++;
}
}
if (kk == 3) {
if ((Connected & B00000001) == 1 ) //is T6700 present?
{ SensorReading = CO2ppmValue;
SensorReading.remove(4);
Units = "ppm";
AuxInfo = "Carbon"; AuxInfo += char(32); AuxInfo += "Dioxide";
Offset = 15;
}
else {
kk++;
}
}
if (kk == 4) {
if ((Connected & B00001000) == 8) { //is dust sensor present?
SensorReading = String(AQIColour);
Units = "";
AuxInfo = "AQI"; AuxInfo += char(32); AuxInfo += "Colour [";
AuxInfo += String(PM2_Value); AuxInfo += "]";
Offset = 0;
}
else {
kk++;
}
}
displayReading(SensorReading, AuxInfo, Units, Offset);
kk++;
#endif
#ifdef USB //output to PC through USB
if ((Connected & B00000001) == 1 ) { //is T6700 present?
Serial.print(CO2ppmValue);
Serial.print (",");
}
if ((Connected & B00000110) == 6 ) { //is T9602 present?
Serial.print(temperature); Serial.print (",");
Serial.print(humidity); Serial.print (",");
}
if ((Connected & B00001000) == 8 ) { //is dust sensor present?
Serial.print(PM2_Value); Serial.print (",");
Serial.print (AQIColour);
}
Serial.println ("");
#endif
}
}
//________________________________Screen Sub Routines_______________________________
#ifdef OELCD_OP
void displaySetupScreen() {
// Clear the buffer.
display.clearDisplay();
display.setTextSize(1);
display.setTextColor(WHITE);
display.setCursor(0, 30);
display.print(SplashScreen);
display.display();
delay(2000);
display.clearDisplay();
}
void displayReading(String aa, String bb, String cc, int dd) {
display.clearDisplay();
// display header detail
display.setTextColor(WHITE);
display.setTextSize(1);
display.setCursor(0, 0); //header
display.print(ScreenHeader);
// display screen header 2nd line
display.setCursor(0, 12);
display.setTextSize(1);
display.print(ScreenFooter);
// display reading
display.setTextSize(3);
display.setCursor(10 + dd, 28);
display.print(aa); //Sensor Reading
// display units
display.setTextSize(1);
display.setCursor(100, 35);
display.print(cc); //units
// display aux info
display.setTextSize(1);
display.setCursor(25, 57);
display.print(bb); //aux info
display.display();
}
#endif
//________________________________________Sensor Sub Routines____________________________
void getT9602data() //gets temp and hum values from T9602 over I2C
{
Wire.beginTransmission(ADDR_9602);
Wire.write(0);
Wire.endTransmission();
byte aa, bb, cc, dd;
Wire.requestFrom(ADDR_9602, 4);
data[0] = Wire.read();
data[1] = Wire.read();
data[2] = Wire.read();
data[3] = Wire.read();
// humidity = (rH_High [5:0] x 256 + rH_Low [7:0]) / 16384 x 100
humidity = (float)(((data[0] & 0x3F ) << 8) + data[1]) / 16384.0 * 100.0;
humidity = round(humidity);
// temperature = (Temp_High [7:0] x 64 + Temp_Low [7:2]/4 ) / 16384 x 165 - 40
temperature = (float)((unsigned)(data[2] * 64) + (unsigned)(data[3] >> 2 )) / 16384.0 * 165.0 - 40.0;
temperature = round(temperature * 10);
temperature = temperature / 10;
}
//gets CO2 ppm value from T6700 series over I2C bus
void getT6700data()
{
// start I2C
Wire.beginTransmission(ADDR_6700);
Wire.write(0x04); Wire.write(0x13); Wire.write(0x8B); Wire.write(0x00); Wire.write(0x01);
// end transmission
Wire.endTransmission();
// read report of current gas measurement in ppm
delay(1);
Wire.requestFrom(ADDR_6700, 6); // request 4 bytes from slave device
data[0] = Wire.read();
data[1] = Wire.read();
data[2] = Wire.read();
data[3] = Wire.read();
CO2ppmValue = ((data[2] & 0x3F ) << 8) | data[3];
}
//calculates the dust value from the stored
void CalculateDustValue()
// sample times accumulated by the interupts.
{
// create local variables to hold a local copies of the channel inputs
// these are declared static so that thier values will be retained
// between calls to loop.
static uint16_t unPM2_In;
static uint16_t unPM2_Time;
// local copy of update flags
static uint8_t bUpdateFlags;
static long PM2_Output[25];
// check shared update flags to see if any channels have a new signal
if (bUpdateFlagsShared)
{
noInterrupts(); // turn interrupts off quickly while we take local copies of the shared variables
bUpdateFlags = bUpdateFlagsShared;
if (bUpdateFlags & PM2_FLAG)
{
unPM2_In = unPM2_InShared;
unPM2_Time = (unPM2_Time + unPM2_In);
}
bUpdateFlagsShared = 0;
interrupts();
}
PM2_Output[SampleCount] = unPM2_Time ;
unPM2_Time = 0;
PM2_Output[0] = PM2_Output[1] + PM2_Output[2] + PM2_Output[3] + PM2_Output[4] + PM2_Output[5] + PM2_Output[6] + PM2_Output[7] + PM2_Output[8] + PM2_Output[9] + PM2_Output[10] + PM2_Output[11] + PM2_Output[12] + PM2_Output[13] + PM2_Output[14] + PM2_Output[15] + PM2_Output[16] + PM2_Output[17] + PM2_Output[18] + PM2_Output[19] + PM2_Output[20] + PM2_Output[21] + PM2_Output[22] + PM2_Output[23] + PM2_Output[24];
/* converts LP outputs to values, calculate % LPO first, then converet to µg/m3 assuming conversion is linear
output (µS) concentration change (250 or 600)
----------------------------------- x 100 x --------------------------------- + offset (0 or 250)
sample rate (mS) x 1000 x NoOfSamples percentage change (3 0r 7)
*/
if (PM2_Output[0] / (samplerate * NoOfSamples * 10 ) >= 3);
{
PM2_Value = round((float)PM2_Output[0] / (samplerate * NoOfSamples * 10 ) * 600 / 7 + 250);
}
{
PM2_Value = round((float)PM2_Output[0] / (samplerate * NoOfSamples * 10 ) * 250 / 3);
}
bUpdateFlags = 0; //reset flags and variables
// Serial.print (PM2_Output[SampleCount]); Serial.print("\t");
if (SampleCount >= NoOfSamples)
{
SampleCount = 1;
// Serial.print (PM2_Output[0]); Serial.print("\t");Serial.println("\t");
}
else
{
SampleCount++;
}
// Colour Values based on US EPA Air Quality Index for PM 2.5 and PM 10
if (PM2_Value <= 12)
{
AQIColour = "Green ";
}
else if (PM2_Value <= 35)
{
AQIColour = "Yellow";
}
else if (PM2_Value <= 55)
{
AQIColour = "Orange";
}
else if (PM2_Value <= 150)
{
AQIColour = char(32);
AQIColour += "Red";
}
else if (PM2_Value <= 250)
{
AQIColour = "Purple";
}
else {
AQIColour = "Maroon";
}
}
// simple interrupt service routine
void calcPM2()
{
if (digitalRead(PM2_IN_PIN) == LOW)
{
ulPM2_Start = micros();
}
else
{
unPM2_InShared = (uint16_t)(micros() - ulPM2_Start);
bUpdateFlagsShared |= PM2_FLAG;
}
}四、程序烧录
1、连接USB数据线至开发板；
2、选择端口号对应的开发板；
3、点击 上传 烧录程序到开发板上；
五、演示效果
启用 #define USB 将在串口输出相关信息；
输出板载 SM-PWM-01C 传感器检测到的数值；
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