查看“Arduino系列教程八：PM2.5灰尘传感器”的源代码




[[File:180624jd7kk3pi7dt1wws0.jpg]]

 本教程实现功能：通过传感器获取当前空气PM2.5的值，并通过串口发送给上位机显示。
<b>PM2.5传感器概述：</b>
 可以检测直径大于0.8um的灰尘颗粒浓度，作为一名创客，想了解空气质量？想DIY一个PM2.5检测仪？想设计一个空气净化器？，那么这款传感器就是你的必备神器
<b>硬件准备：</b>
<li>
UNO PLUS
</li><li>
I/O Expansion Shield
</li><li>
Dust Sensor
</li>
<b>硬件连接：</b>
 1. 将IO Expansion 扩展板接入UNO PLUS，用跳线帽将两个板子的电压都配置为 5V
 2. Dust Sensor 与IO Expansion的连接
 VCC   --   VCC
 GND  --   GND
 AOUT --  A5
 ILED  --  D2
 3. 连接效果如下图


[[File:182933mti1bzrt3oqt3tz4.jpg]]





<b>程序：</b>

<syntaxhighlight lang="python">
#define        COV_RATIO                       0.2            //ug/mmm / mv
#define        NO_DUST_VOLTAGE                 400            //mv
#define        SYS_VOLTAGE                     5000           //ADC参考电压    

/*
I/O define
*/
const int iled = 2;                                           //drive the led of sensor
const int vout = 5;                                           //analog input

/*
variable
*/
float density, voltage;
int   adcvalue;

/*
private function
*/
int Filter(int m)
{
  static int flag_first = 0, _buff[10], sum;
  const int _buff_max = 10;
  int i;
  
  if(flag_first == 0)
  {
    flag_first = 1;

    for(i = 0, sum = 0; i < _buff_max; i++)
    {
      _buff[i] = m;
      sum += _buff[i];
    }
    return m;
  }
  else
  {
    sum -= _buff[0];
    for(i = 0; i < (_buff_max - 1); i++)
    {
      _buff[i] = _buff[i + 1];
    }
    _buff[9] = m;
    sum += _buff[9];
    
    i = sum / 10.0;
    return i;
  }
}


void setup(void)
{
  pinMode(iled, OUTPUT);
  digitalWrite(iled, LOW);                                     //iled default closed
  
  Serial.begin(9600);                                          //send and receive at 9600 baud
  Serial.print("*********************************** WaveShare ***********************************\n");
}

void loop(void)
{
  /*
  get adcvalue
  */
  digitalWrite(iled, HIGH);
  delayMicroseconds(280);
  adcvalue = analogRead(vout);
  digitalWrite(iled, LOW);
  
  adcvalue = Filter(adcvalue);
  
  /*
  covert voltage (mv)
  */
  voltage = (SYS_VOLTAGE / 1024.0) * adcvalue * 11;
  
  /*
  voltage to density
  */
  if(voltage >= NO_DUST_VOLTAGE)
  {
    voltage -= NO_DUST_VOLTAGE;
    
    density = voltage * COV_RATIO;
  }
  else
    density = 0;
    
  /*
  display the result
  */
  Serial.print("The current dust concentration is: ");
  Serial.print(density);
  Serial.print(" ug/m3\n");  
  
  delay(1000);
}</syntaxhighlight> 



<b>实现输出：</b>


[[File:183005f800q94zshv8s0v3.jpg]]


<b>程序代码下载：</b>

<a class="attach" href="portal.php?mod=attachment&amp;id=33" target="_blank">DustSensor.zip