Temp/Humidity Sensor with 128x64 LCD

temp-humidity 128x64.c

#include "DHT.h"
#include "U8glib.h"

#define DHTPIN 5  // data pin for DHT 22
#define DHTTYPE DHT22  // Identifier from library. Will not work without this!

DHT dht(DHTPIN, DHTTYPE);
U8GLIB_ST7920_128X64_4X u8g(13, 11, 10);	// SPI Com: SCK = en = 18, MOSI = rw = 16, CS = di = 17

void draw()
{
  float hum_r[2];  // used for himidity reading. the first in the array is the actual reading, the second is truncated to x.xx
  float temp_r[2];  // used for temp reading. same rules apply as for the humidity formatting
  int hum;  // used for truncation of humidity reading (float hum_r * 100), then convert to an integer for rounding, then truncate
  int temp; // same as hum
  byte high_temp = 24;  // highest allowable temperature in the house in degrees Celsius
  byte low_temp = 21;  // lowest allowable temperature in the house in degrees Celsius

  u8g.setColorIndex(1);
  u8g.setFont(u8g_font_6x10);

  hum_r[1] = dht.readHumidity();
  temp_r[1] = dht.readTemperature();
  // this next whole block of code is just for truncating decimals beyond XX.xx When it takes the initial hum/temp reading, it takes
  // many more decimal places than this, so I round->truncate it for comparison and display purposes.
  hum = hum_r[1] * 100;
  temp = temp_r[1] * 100;
  hum_r[1] = hum;
  temp_r[1] = temp;
  hum_r[1] = hum_r[1] / 100;
  temp_r[1] = temp_r[1] / 100;
  // now everything's rounded and truncated, and put back into a decimal XX.xx

  if (isnan(temp_r[1]) or isnan(hum_r[1]))
  {
    u8g.setPrintPos(0, 7);
    u8g.print("Invalid data! Check your wiring.");
    delay(5000);  // this means it got values from the sensor that weren't real numbers, so it was probably garbage data.
    // So I put a delay in here for 5 seconds to give it a chance to get real data. If it doesn't do anything
    // for another 5 seconds, we got a problem. Check your wiring.
  }
  else
  {
    byte seconds, minutes, hours, days;
    seconds = millis() / 1000 % 60;
    minutes = millis() / 1000 / 60 % 60;
    hours = millis() / 1000 / 60 / 60 % 24;
    days = millis() / 1000 / 60 / 60 / 24;

    u8g.drawBox(0, 0, 127, 10);
    u8g.setColorIndex(0);
    u8g.setPrintPos(1, 8);
    u8g.print("All temps in DEG C");
    u8g.setColorIndex(1);
    u8g.setPrintPos(1, 18);
    u8g.print("Hi=");
    u8g.print(high_temp);
    u8g.print(".0");
    u8g.print("   Temp=");
    u8g.print(temp_r[1]);
    u8g.setPrintPos(1, 26);
    u8g.print("Lo=");
    u8g.print(low_temp);
    u8g.print(".0");
    u8g.setPrintPos(1, 40);
    u8g.print("H=");
    u8g.print(hum_r[1]);
    u8g.print("%");
    u8g.setPrintPos(1, 63);
    u8g.print(days);
    u8g.print("d ");
    u8g.print(hours);
    u8g.print("h ");
    u8g.print(minutes);
    u8g.print("m ");
    u8g.print(seconds);
    u8g.print("s");
    
    if (temp_r[1] > high_temp)
    {
      u8g.drawFrame(65, 30, 29, 13);
      u8g.setPrintPos(68, 40);
      u8g.print("Heat");
      u8g.drawBox(100, 30, 25, 13);
      u8g.setColorIndex(0);
      u8g.setPrintPos(104, 40);
      u8g.print("A/C");
    }
    else if (temp_r[1] < low_temp)
    {
      u8g.drawFrame(100, 30, 25, 13);
      u8g.setPrintPos(104, 40);
      u8g.print("A/C");
      u8g.drawBox(65, 30, 29, 13);
      u8g.setColorIndex(0);
      u8g.setPrintPos(68, 40);
      u8g.print("Heat");
    }
    else
    {
      u8g.drawFrame(65, 30, 29, 13);
      u8g.setPrintPos(68, 40);
      u8g.print("Heat");
      u8g.drawFrame(100, 30, 25, 13);
      u8g.setPrintPos(104, 40);
      u8g.print("A/C");
    }
  }

  hum_r[0] = hum_r[1];
  temp_r[0] = temp_r[1];
}

void setup()
{
  dht.begin();
  delay(200);
}

void loop()
{
  do
  {
    draw();
  } while (u8g.nextPage());
}