Do I need to buy hardware for this tutorial?

No. Everything runs in the browser: Circuitly simulates the board, the components and the code. Real hardware is optional if you want to rebuild the circuit afterwards.

Which components are used?

Arduino UNO board, ST7789 TFT display (SPI). They are already available in the simulator library.

How long does it take?

About 30 minutes, expert level, in 4 guided steps.

What should I know before starting?

The previous tutorial in the series, “16×2 LCD display”, is enough preparation. No software install is required.

Is the code provided and checked?

Yes: a starter sketch is provided, and the simulator checks your wiring and your code automatically at every step.

All tutorials

4 · Displays & buses

Colour TFT screen over SPI

Expert30 min

Goal

Drive a 240×240 ST7789 with the hardware SPI port.

Why it matters

SPI is far faster than I²C: essential for video.

What you need

Arduino UNO board
ST7789 TFT display (SPI)

Nothing to buy: every component below is simulated in the browser.

Steps

01Drag the TFT 240×240 (SPI) component onto the canvas.
02Keep DC on D8 — SCK is D13 and MOSI is D11 on the UNO.
03Load the starter sketch: it initialises the panel and draws colour bars.
04Edit the colour array to draw your own interface.

Starter sketch

// ST7789 240x240 SPI display driven directly — DC on D8, RST on D9, CS on D10.
#include <SPI.h>

#define TFT_DC 8
#define TFT_RST 9
#define TFT_CS 10

void cmd(uint8_t c) {
  digitalWrite(TFT_DC, LOW);
  digitalWrite(TFT_CS, LOW);
  SPI.transfer(c);
  digitalWrite(TFT_CS, HIGH);
}

void dat(uint8_t d) {
  digitalWrite(TFT_DC, HIGH);
  digitalWrite(TFT_CS, LOW);
  SPI.transfer(d);
  digitalWrite(TFT_CS, HIGH);
}

void window(int x0, int y0, int x1, int y1) {
  cmd(0x2A); dat(x0 >> 8); dat(x0); dat(x1 >> 8); dat(x1);
  cmd(0x2B); dat(y0 >> 8); dat(y0); dat(y1 >> 8); dat(y1);
  cmd(0x2C);
}

void fill(int x, int y, int w, int h, uint16_t color) {
  window(x, y, x + w - 1, y + h - 1);
  digitalWrite(TFT_DC, HIGH);
  digitalWrite(TFT_CS, LOW);
  for (long i = 0; i < (long)w * h; i++) {
    SPI.transfer(color >> 8);
    SPI.transfer(color & 0xFF);
  }
  digitalWrite(TFT_CS, HIGH);
}

void setup() {
  pinMode(TFT_DC, OUTPUT);
  pinMode(TFT_RST, OUTPUT);
  pinMode(TFT_CS, OUTPUT);
  digitalWrite(TFT_CS, HIGH);
  SPI.begin();

  digitalWrite(TFT_RST, LOW); delay(20);
  digitalWrite(TFT_RST, HIGH); delay(50);

  cmd(0x01); delay(50);   // software reset
  cmd(0x11); delay(50);   // sleep out
  cmd(0x3A); dat(0x55);   // 16-bit color
  cmd(0x36); dat(0x00);   // memory access
  cmd(0x21);              // inversion on (typical for 240x240 panels)
  cmd(0x29);              // display on

  fill(0, 0, 240, 240, 0x0000);
}

uint16_t bar = 0;

void loop() {
  const uint16_t colors[4] = { 0xF800, 0x07E0, 0x001F, 0xFFE0 };
  fill(0, (bar % 4) * 60, 240, 60, colors[bar % 4]);
  bar++;
  delay(400);
}

This tutorial runs inside the Circuitly simulator: your wiring and your code are checked automatically at every step.

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Frequently asked questions

Do I need to buy hardware for this tutorial?: No. Everything runs in the browser: Circuitly simulates the board, the components and the code. Real hardware is optional if you want to rebuild the circuit afterwards.
Which components are used?: Arduino UNO board, ST7789 TFT display (SPI). They are already available in the simulator library.
How long does it take?: About 30 minutes, expert level, in 4 guided steps.
What should I know before starting?: The previous tutorial in the series, “16×2 LCD display”, is enough preparation. No software install is required.
Is the code provided and checked?: Yes: a starter sketch is provided, and the simulator checks your wiring and your code automatically at every step.

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