아두이노 온도 습도 미터기 DHT11 과 OLED display 사용

아두이노 온도 습도 미터기 DHT11 과 OLED display 사용

Arduino Nano Humidity Meter with DHT11 and I2C OLED display

아두이노 나노를 사용하였다. 연결은 아래 두 개를 합친다.

아두이노 나노와 OLED 연결도 - OLED는 I2C 인터페이스 이므로 아래 그림과 같이 A4, A5 번이 SDA, SCL 에 연결해야 한다. 

VCC – VCC

GND - GND

SCL – A5

SDA – A4

이미지 출처 : https://www.instructables.com/id/Monochrome-096-i2c-OLED-display-with-arduino-SSD13/

 이렇게 연결을 한다.

다음은 아두이노 나노와 온도 습도 센서 DHT11 을 연결한다. 

주의할 점은 아래 도면은 아두이노 우노의 7번 핀에 연결되었지만 실제 소스코드는 2번 핀에 연결되므로 2번에 연결해 준다. 아니면 7번에 연결하고 코드에서 7번으로 수정해도 마찬가지로 잘 동작한다. 원리가 중요하다. 

아래 동작하는  소스코드를 옮긴다. 소스코드 출처는 https://gist.github.com/embeddeduser/e7adc347397f1b3d1a9ae7e2598b4dc3 이고 보드에 맞게 수정하였다. 로그인 해야 코드를 볼 수 있다. 참고하기 바란다. 

// Written by EmbeddedUser 
// Refer to blog http://www.jaimeferns.in/2016/10/how-to-build-humidity-and-temperature.html
// Youtube Video https://www.youtube.com/watch?v=g-rcEd_2I-w
// Humidity meter with DHT11, Arduino and I2c OLED display
// Now support displaying sensor error and configuring deg C or deg F
 
#include <DHT.h>   //온도 습도센서 라이브러리
#include "U8glib.h"  //OLED 라이브러리
 
// Display defaults to Degree F. TO use metric display,
// comment out next line to display temperature in Degree C,
#define METRIC  //이걸 살리면 섭씨 셀지우스, 주석처리하면 화씨 온도표시
 
#define DHTPIN 2          // what digital pin we're connected to
// Uncomment whatever type you're using!
#define DHTTYPE DHT11     // DHT 11
//#define DHTTYPE DHT22   // DHT 22  (AM2302), AM2321
//#define DHTTYPE DHT21   // DHT 21 (AM2301)
 
// Connect pin 1 (on the left) of the sensor to +5V
// NOTE: If using a board with 3.3V logic like an Arduino Due connect pin 1
// to 3.3V instead of 5V!
// Connect pin 2 of the sensor to whatever your DHTPIN is
// Connect pin 4 (on the right) of the sensor to GROUND
// Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor
 
// Initialize DHT sensor.
// Note that older versions of this library took an optional third parameter to
// tweak the timings for faster processors.  This parameter is no longer needed
// as the current DHT reading algorithm adjusts itself to work on faster procs.
DHT dht(DHTPIN, DHTTYPE);
 
U8GLIB_SSD1306_128X64 u8g(U8G_I2C_OPT_NONE);  // 사용하는 OLE에 맞는 것 선택 반드시!
//U8GLIB_SSD1306_128X64 u8g(U8G_I2C_OPT_NO_ACK);  // Display which does not send AC
//U8GLIB_SSD1306_128X64 u8g(U8G_I2C_OPT_NONE|U8G_I2C_OPT_DEV_0);  // I2C / TWI
//U8GLIB_SSD1306_128X64 u8g(U8G_I2C_OPT_DEV_0|U8G_I2C_OPT_NO_ACK|U8G_I2C_OPT_FAST); // Fast I2C / TWI
//U8GLIB_SSD1306_128X64 u8g(U8G_I2C_OPT_NO_ACK);  // Display which does not send AC
 
const uint8_t logo[] PROGMEM =
{
  0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
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  0xc0, 0x1c, 0x30, 0x0, 0x0, 0x1, 0xff, 0x8e, 0xc, 0x63, 0x30, 0x18, 0x1c, 0x38, 0x6,
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  0x31, 0xff, 0x8f, 0xd8, 0x7f, 0xe0, 0xfe, 0x3, 0xc0, 0x0, 0x0, 0x1, 0xc3, 0x83, 0xcc,
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  0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
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  0x0, 0x0, 0x0, 0x0
};
 
bool first = true;
float hum = 0.0;
float temp = 0.0;
float hIndex = 0.0;
bool dht_test(float* humPerc, float* tempF, float* heatIndex);
 
void setup(void)
{
  Serial.begin(9600);
  dht.begin();
  first = true;
 
  // assign default color value
  if (u8g.getMode() == U8G_MODE_R3G3B2)
  {
    u8g.setColorIndex(255);     // white
  }
  else if (u8g.getMode() == U8G_MODE_GRAY2BIT)
  {
    u8g.setColorIndex(3);         // max intensity
  }
  else if (u8g.getMode() == U8G_MODE_BW)
  {
    u8g.setColorIndex(1);         // pixel on
  }
  else if (u8g.getMode() == U8G_MODE_HICOLOR)
  {
    u8g.setHiColorByRGB(255, 255, 255);
  }
 
  // picture loop
  u8g.firstPage();
 
  do
  {
    u8g.drawBitmapP(0, 0, 16, 64, logo);
  }
  while (u8g.nextPage());
 
  dht_test(&hum, &temp, &hIndex);
}
void HumMeter(float* humPerc, float* temp, float* heatIndex)
{
  u8g.setFont(u8g_font_fub11);
  u8g.setFontRefHeightExtendedText();
  u8g.setDefaultForegroundColor();
  u8g.setFontPosTop();
  u8g.drawStr(4, 0, "Hum %");
  u8g.setPrintPos(80, 0);
  u8g.print(*humPerc);
#ifdef METRIC
  // if metric system, display Celsius
  u8g.drawStr(4, 20, "Temp C");
#else
  //display Farenheit
  u8g.drawStr(4, 20, "Temp F");
#endif
 
  u8g.setPrintPos(80, 20);
  u8g.print(*temp);
  u8g.drawStr(4, 40, "Heat Ind");
  u8g.setPrintPos(80, 40);
  u8g.print(*heatIndex);
}
 
void loop(void)
{
  bool result = dht_test(&hum, &temp, &hIndex);
 
  if (first)
  {
    // skip displaying readings first time, as its stale data.
    first = false;
  }
  else
  {
    if(result == false)
    {
      u8g.firstPage();
      do 
      {
        // sensor error
        u8g.setFont(u8g_font_fub11);
        u8g.setFontRefHeightExtendedText();
        u8g.setDefaultForegroundColor();
        u8g.setFontPosTop();
        u8g.drawStr(10, 30, "Sensor Error");
      }
      while (u8g.nextPage());
    }
    else
    {
      u8g.firstPage();
      do
      {
        HumMeter(&hum, &temp, &hIndex);
      }
      while (u8g.nextPage());
    }
  }
}
bool dht_test(float* humPerc, float* temp, float* heatIndex)
{
  // Wait a few seconds between measurements.
  delay(2000);
  *humPerc = 0;
  *temp = 0;
  *heatIndex = 0;
  
  // Reading temperature or humidity takes about 250 milliseconds!
  // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
  float h = dht.readHumidity();
  // Read temperature as Celsius (the default)
  float t = dht.readTemperature();
  // Read temperature as Fahrenheit (isFahrenheit = true)
  float f = dht.readTemperature(true);
 
  // Check if any reads failed and exit early (to try again).
  if (isnan(h) || isnan(t) || isnan(f))
  {
    Serial.println("Failed to read from DHT sensor!");
    return false;
  }
 
  // Compute heat index in Fahrenheit (the default)
  float hif = dht.computeHeatIndex(f, h);
  // Compute heat index in Celsius (isFahreheit = false)
  float hic = dht.computeHeatIndex(t, h, false);
 
  Serial.print("Humidity: ");
  Serial.print(h);
  Serial.print(" %\t");
  Serial.print("Temperature: ");
  Serial.print(t);
  Serial.print(" *C ");
  Serial.print(f);
  Serial.print(" *F\t");
  Serial.print("Heat index: ");
  Serial.print(hic);
  Serial.print(" *C ");
  Serial.print(hif);
  Serial.println(" *F");
  *humPerc = h;
#ifdef METRIC
  // metric system, load degree celsius
  *temp = t;
  *heatIndex = hic;
#else
  *temp = f;
  *heatIndex = hif;
#endif
  return true;
}
 
 

아래는 동작사진이다. 실제 OLED 에 표시되는 모양과 씨리얼 포트에 출력하는 결과를 나타낸다.