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#include <Wire.h>
#include <dht.h>
U8GLIB_SSD1306_128X64 (U8G_I2C_OPT_NONE);
dht DHT;
#define DHT22_PIN 2
struct
{
uint32_t total;
uint32_t ok;
uint32_t crc_error;
uint32_t time_out;
uint32_t connect;
uint32_t ack_l;
uint32_t ack_h;
uint32_t unknown;
} stat = { 0,0,0,0,0,0,0,0};
int humidity;
double temperature;
double temperatureF;
int dewPoint1;
String thisTemp = "";
String thisHumidity = "";
String thisDewPoint = "";
void draw(void) {
u8g.setFont(u8g_font_9x15);
u8g.drawStr(39,10, "BD7IWD");
u8g.setFont(u8g_font_9x15);
thisTemp = String(temperature) + "260C";
const char* newTempC = (const char*) thisTemp.c_str();
u8g.drawStr(55,35, newTempC);
u8g.setFont(u8g_font_9x15);
u8g.drawStr(8,35, "Temp=");
u8g.setFont(u8g_font_9x15);
thisHumidity = String(humidity) + "%";
const char* newHumidity = (const char*) thisHumidity.c_str();
u8g.drawStr(95,55, newHumidity);
u8g.setFont(u8g_font_9x15);
u8g.drawStr(15,55, "humidity=");
}
void setup(void) {
Serial.begin(9600);
Wire.begin();
Serial.println("DHT22");
Serial.print("LIBRARY VERSION: ");
Serial.println(DHT_LIB_VERSION);
Serial.println();
}
void loop(void) {
uint32_t start = micros();
int chk = DHT.read22(DHT22_PIN);
uint32_t stop = micros();
stat.total++;
switch (chk)
{
case DHTLIB_OK:
stat.ok++;
Serial.print("OK,t");
break;
case DHTLIB_ERROR_CHECKSUM:
stat.crc_error++;
Serial.print("Checksum error,t");
break;
case DHTLIB_ERROR_TIMEOUT:
stat.time_out++;
Serial.print("Time out error,t");
break;
case DHTLIB_ERROR_CONNECT:
stat.connect++;
Serial.print("Connect error,t");
break;
case DHTLIB_ERROR_ACK_L:
stat.ack_l++;
Serial.print("Ack Low error,t");
break;
case DHTLIB_ERROR_ACK_H:
stat.ack_h++;
Serial.print("Ack High error,t");
break;
default:
stat.unknown++;
Serial.print("Unknown error,t");
break;
}
temperature = DHT.temperature;
humidity = DHT.humidity;
dewPoint(temperature,humidity);
u8g.firstPage();
do {
draw();
} while( u8g.nextPage() );
delay(2000);
}
double dewPoint(double celsius, double humidity)
{
double a = 17.271;
double b = 237.7;
double temp = (a * celsius) / (b + celsius) + log(humidity/100);
dewPoint1 = (b * temp) / (a - temp);
}
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