44. Project: TFT Sensor Display

This lesson uses: Arduino UNO R3 board, TinkerBlock TK89 1.8'' TFT module, TinkerBlock TK38 DHT11 module, jumper wires (or breadboard). Project: show sensor data on TFT; outcome: screen refreshes periodically with current temperature and humidity (Temp: xxC, Humi: xx%).

1. Project goal

Build a sensor display system:

• Read DHT11 temperature and humidity
• Show temperature and humidity on the TFT screen

2. Wiring

• TK89 TFT: GND → GND, VCC → 5V, CS → D10, RST → D8, DC → D9, MOSI → D11, SCK → D13, LED → 3.3V or 5V
• TK38 DHT11: GND → GND, VCC → 5V, DATA → D2

3. Program structure

Same as last lesson: two fixed blocks setup() and loop().

• setup(): Include libraries, init display and sensor; runs once.
• loop(): Keep repeating “read sensor → show on screen → wait → repeat”.

Temp and humidity are shown on the TFT and refresh every few seconds.

4. Code to write

Type the code below at the top of the file and in setup() and loop() (do not copy-paste; typing it yourself helps you remember):

// TFT shows DHT11 temp/humidity; refresh every 2 s
#include <Adafruit_GFX.h>
#include <Adafruit_ST7735.h>
#include <SPI.h>
#include <DHT.h>
#define CS_PIN 10   // TFT SPI CS
#define RST_PIN 8
#define DC_PIN 9
#define DHTPIN 2    // DHT11 DATA
#define DHTTYPE DHT11

Adafruit_ST7735 tft = Adafruit_ST7735(CS_PIN, DC_PIN, RST_PIN);
DHT dht(DHTPIN, DHTTYPE);

void setup() {
  tft.initR(INITR_BLACKTAB);
  tft.fillScreen(ST7735_BLACK);
  tft.setTextColor(ST7735_WHITE);
  tft.setTextSize(2);
  dht.begin();
}

void loop() {
  float humidity = dht.readHumidity();
  float temperature = dht.readTemperature();
  tft.fillScreen(ST7735_BLACK);   // Clear before redraw to avoid ghosting
  tft.setCursor(10, 10);
  tft.print("Temp: ");
  tft.print(temperature);
  tft.println("C");
  tft.setCursor(10, 40);
  tft.print("Humi: ");
  tft.print(humidity);
  tft.println("%");
  delay(2000);   // Update every 2 s
}

Program notes

Overall idea: DHT reads temp/humidity; TFT uses fillScreen to clear then setCursor + print for "Temp: xx" and "Humi: xx", refresh every 2 s. This example uses Adafruit_ST7735; if you use Arduino_GFX (e.g. L24) replace the library and init, logic is the same.

5. Hands-on

1. After entering the code, click Verify (✓) to compile
2. Click Upload (→) to upload to the board
3. Watch TK89 TFT: current temperature and humidity
4. Try yourself: add more sensor data (e.g. light, voltage)

Expected result: TFT shows current temp/humidity and other sensor data.

Proceed to Lesson 45.

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