Beautifully Finished Humidity and Temperature Sensor © GPL3+

#include <Adafruit_NeoPixel.h>
#include <Adafruit_ST7735.h>
#include <Adafruit_GFX.h>
#include <FastLED.h>
#include <SPI.h>
#include <SD.h>
#include <cactus_io_DHT22.h> // There's a bunch of DHTXX libraries you can find online. They all have varying levels of features.

// Define Pins
#define TFT_CS    10
#define TFT_RST   9
#define TFT_DC    8
#define DHT_PIN   2
#define PIXEL_PIN 6
#define PIXEL_NUM 24
#define SD_PIN    4
#define BMP_BUF   20  

// Global Variables
int currentColor = 9999; //(Numbers correspond to chart. See below.)
CRGB leds[PIXEL_NUM];
Adafruit_ST7735   tft = Adafruit_ST7735(TFT_CS, TFT_DC, TFT_RST);
DHT22 dht(DHT_PIN);
int loopDelay = 2000; //ms

// SETUP
void setup() {
 
  Serial.begin(9600);
  Serial.println("Starting up.");

  // Begin DHT
  dht.begin();

  // Initialize LCD Screen
  tft.initR(INITR_144GREENTAB);

  // Initialize SD Card
  Serial.print("Initializing SD card.");
  if (!SD.begin(SD_PIN)) {
    Serial.println("Failed!");
    return;
  }

  // Set Screen Background to Black
  tft.fillScreen(ST7735_BLACK);

  // Initialize LEDs
  FastLED.addLeds<NEOPIXEL, PIXEL_PIN>(leds, PIXEL_NUM);

  // Let everything catch up before starting loop
  delay(500);

}


// LOOP
void loop() {

  // Get Sensor Data
  dht.readTemperature();
  dht.readHumidity();
  int f = dht.temperature_F; // Degrees in Fahrenheit
  int h = dht.humidity; // Percentage

  // Draw Degrees Icon
  tft.fillCircle(102, 42, 6, ST7735_WHITE);
  tft.fillCircle(102, 42, 4, ST7735_BLACK);

  // Draw Temperature on LCD Screen
  drawTemperature(f);

  // Humidity
  setHumidityColors(h);
  
  //Print Data to Serial Monitor
  Serial.print("Temperature: ");
  Serial.println(f);
  Serial.print("Humidity: ");
  Serial.print(h);
  Serial.println("%");

  // Delay
  delay(1000);
  
}


// Draw Bitmap - This is for the LCD Screen
void bmpDraw(char *filename, uint8_t x, uint8_t y) {

  File     bmpFile;
  int      bmpWidth, bmpHeight;   // W+H in pixels
  uint8_t  bmpDepth;              // Bit depth (currently must be 24)
  uint32_t bmpImageoffset;        // Start of image data in file
  uint32_t rowSize;               // Not always = bmpWidth; may have padding
  uint8_t  sdbuffer[3*BMP_BUF];   // pixel buffer (R+G+B per pixel)
  uint8_t  buffidx = sizeof(sdbuffer); // Current position in sdbuffer
  boolean  goodBmp = false;       // Set to true on valid header parse
  boolean  flip    = true;        // BMP is stored bottom-to-top
  int      w, h, row, col;
  uint8_t  r, g, b;
  uint32_t pos = 0, startTime = millis();

  if((x >= tft.width()) || (y >= tft.height())) return;

//  Serial.println();
//  Serial.print("Loading Bitmap Image: '");
//  Serial.print(filename);
//  Serial.println('\'');

  // Open requested file on SD card
  if ((bmpFile = SD.open(filename)) == NULL) {
    Serial.print("Bitmap file not found!");
    return;
  }

  // Parse BMP header
  if(read16(bmpFile) == 0x4D42) {
    read32(bmpFile);
    (void)read32(bmpFile);
    bmpImageoffset = read32(bmpFile);
    //Serial.println());
    read32(bmpFile);
    bmpWidth  = read32(bmpFile);
    bmpHeight = read32(bmpFile);
    if(read16(bmpFile) == 1) {
      bmpDepth = read16(bmpFile);
      //Serial.print("Bit Depth: ");
      if((bmpDepth == 24) && (read32(bmpFile) == 0)) {

        goodBmp = true;

        // BMP rows are padded (if needed) to 4-byte boundary
        rowSize = (bmpWidth * 3 + 3) & ~3;

        // If bmpHeight is negative, image is in top-down order.
        // This is not canon but has been observed in the wild.
        if(bmpHeight < 0) {
          bmpHeight = -bmpHeight;
          flip      = false;
        }

        // Crop area to be loaded
        w = bmpWidth;
        h = bmpHeight;
        if((x+w-1) >= tft.width())  w = tft.width()  - x;
        if((y+h-1) >= tft.height()) h = tft.height() - y;

        // Set TFT address window to clipped image bounds
        tft.setAddrWindow(x, y, x+w-1, y+h-1);

        for (row=0; row<h; row++) { // For each scanline...
          if(flip) {
            pos = bmpImageoffset + (bmpHeight - 1 - row) * rowSize;
          } else {
            pos = bmpImageoffset + row * rowSize;
          }
          if(bmpFile.position() != pos) {
            bmpFile.seek(pos);
            buffidx = sizeof(sdbuffer);
          }

          for (col=0; col<w; col++) {
            if (buffidx >= sizeof(sdbuffer)) {
              bmpFile.read(sdbuffer, sizeof(sdbuffer));
              buffidx = 0;
            }

            // Convert pixel from BMP to TFT format, push to display
            b = sdbuffer[buffidx++];
            g = sdbuffer[buffidx++];
            r = sdbuffer[buffidx++];
            tft.pushColor(tft.Color565(r,g,b));
          }
        }
      }
    }
  }

  bmpFile.close();
  if(!goodBmp) Serial.println("BMP format not recognized.");

}

// This is for the Bitmap/LCD Screen
uint16_t read16(File f) {
  uint16_t result;
  ((uint8_t *)&result)[0] = f.read(); // LSB
  ((uint8_t *)&result)[1] = f.read(); // MSB
  return result;
}

// This is for the Bitmap/LCD Screen
uint32_t read32(File f) {
  uint32_t result;
  ((uint8_t *)&result)[0] = f.read(); // LSB
  ((uint8_t *)&result)[1] = f.read();
  ((uint8_t *)&result)[2] = f.read();
  ((uint8_t *)&result)[3] = f.read(); // MSB
  return result;
}


// Draw Temperature on LCD Screen
void drawTemperature(int temp) {

  // Get Number of Digits in the Temperature
  int digits = numDigits(temp);
 
  // Define Cursor Positions to Draw Bitmaps
  int x1_2 = 62;
  int x2_2 = 32;
  int x1_3 = 1;
  int x2_3 = 1;
  int x3_3 = 1;
  int y = 38;

  char digit1[12];
  char digit2[12];
  char digit3[12];
  char digitStr1[24];
  char digitStr2[24];
  char digitStr3[24];
  
  // Get First Digit
  itoa(temp % 10, digit1,10); 
  //Serial.println(temp % 10);
  strcpy(digitStr1, "");
  strcat(digitStr1, digit1);
  strcat(digitStr1, ".bmp");

  // Get Second Digit
  if(digits == 2){
    itoa((temp / 10) % 10, digit2,10);
    strcpy(digitStr2, "");
    strcat(digitStr2, digit2);
    strcat(digitStr2, ".bmp");
  }

  // Get Third Digit
  if(digits == 3){
    itoa((temp / 100) % 10, digit3,10);
    strcpy(digitStr3, "");
    strcat(digitStr3, digit3);
    strcat(digitStr3, ".bmp");
  }  
  
  if(digits > 2){
    bmpDraw(digitStr1,x1_3,y);
    bmpDraw(digitStr2,x2_3,y);
    bmpDraw(digitStr3,x3_3,y);
  } else {
    bmpDraw(digitStr1,x1_2,y);
    bmpDraw(digitStr2,x2_2,y);
  }

}


// Get number of digits in temperature to determine placement on screen
int numDigits(int number){

  int valLen = 0;  
  if(number > 99)
    valLen = 3;
  else
    valLen = 2;
  return valLen;

}


// Set LED Colors
void setColors(int r, int g, int b){

  for(int i = 0; i < PIXEL_NUM; i++){
    
    leds[i].setRGB( r, g, b);
    leds[i].fadeLightBy(125);
    FastLED.show();    
    delay(100);
  
  }
  
}


// Determine which colors to use based on Humidity level
void setHumidityColors(int humidity){

  // Humidity Color Chart - This is just something we came up with.
  // Red - 0-17%
  // Orange - 18-34%
  // Yellow - 35-51%
  // Green - 52-68%
  // Blue - 69-85%
  // Purple - 86-100%

  // Define Colors
  int cRed[3] = {255,0,0};
  int cOrange[3] = {255,90,0};
  int cYellow[3] = {255,255,0};
  int cGreen[3] = {0,255,0};
  int cBlue[3] = {0,175,255};
  int cPurple[3] = {255,0,255};

  int range = map(humidity, 0, 100, 0, 6);
  switch (range) {
    case 0:    // Red
      if(currentColor == 0){
        break;
      }
      else {
        setColors(cRed[0], cRed[1], cRed[2]);
        currentColor = 0;
      }
      break;
    case 1:    // Orange
      if(currentColor == 1){
        break;
      }
      else {
        setColors(cOrange[0], cOrange[1], cOrange[2]);
        currentColor = 1;
      }
      break;
    case 2:    // Yellow
      if(currentColor == 2){
        break;
      }
      else {
        setColors(cYellow[0], cYellow[1], cYellow[2]);
        currentColor = 2;
      }
      break;
    case 3:    // Green
      if(currentColor == 3){
        break;
      }
      else {
        setColors(cGreen[0], cGreen[1], cGreen[2]);
        currentColor = 3;
      }
      break;
    case 4:    // Blue
      if(currentColor == 4){
        break;
      }
      else {
        setColors(cBlue[0], cBlue[1], cBlue[2]);
        currentColor = 4;
      }
      break;
    case 5:    // Purple
      if(currentColor == 5){
        break;
      }
      else {
        setColors(cPurple[0], cPurple[1], cPurple[2]);
        currentColor = 5;
      }      
      break;
  }
}