Using a TFT LCD Display
What is the TFT LCD Display?
A TFT LCD display is a type of screen that uses Thin-Film Transistor (TFT) technology to control the pixels of a Liquid Crystal Display (LCD). It is one of the most common display types found in devices like smartphones, tablets, monitors, car dashboards, industrial equipment, and many embedded electronics.
In this tutorial, we will be using JOY-IT SBC-LCD01 with SPI communication.
3.3V Logic
A lot of LCD displays have a logic level of 3.3V, including SBC-LCD01. If you use any classic Arduino (UNO and Leonardo) with 5V logic, the display may misbehave. 3.3V Arduino includes Due, Zero, Nano 33 and MKR series. In this tutorial, we will be using Nano 33 Sense Rev2.
Wiring
Wiring up the sensor is simple:
Find the correct Pins for SPI communication
Every Arduino model has their own unique pinout. Make sure you are using the correct pins for SPI clock and MOSI.
- VCC to 3.3V
- GND to GND
- SCL to SPI CLock Pin (Pin 13 on Nano 33 Sense)
- SDA to SPI MOSI Pin (Pin 11 on Nano 33 Sense)
- RST to Pin 4
- DC to Pin 5
Library
To use this code you will need the Adafruit ST7735 and ST7789 Library and Adafruit GFX Library
We have a tutorial on how to install a library here.
Getting started
This code will display "Joy-IT" on the screen.
#include <Adafruit_GFX.h>
#include <Adafruit_ST7789.h>
#include <SPI.h>
#define CS -1 // Declaration of Chip Select
#define DC 5 // Declaration of Data / Command Pin
#define RST 4 // Declaration of RESET Pin
Adafruit_ST7789 lcd = Adafruit_ST7789(CS, DC, RST);
void setup(void) {
lcd.init(240, 240, SPI_MODE2);
lcd.setRotation(1);
delay(500);
// fill Display with a colour and a String
lcd.fillScreen(0x22ED);
lcd.setCursor(20, 100);
lcd.setTextColor(ST77XX_WHITE);
lcd.setTextSize(6);
lcd.print("Joy-IT");
}
void loop() {
// empty
}
This example code is modified from the library to fit the Joy-It LCD display.
#include <Adafruit_GFX.h> // Core graphics library
#include <Adafruit_ST7789.h> // Hardware-specific library for ST7789
#include <SPI.h>
#define CS -1 // Declaration of Chip Select
#define DC 5 // Declaration of Data / Command Pin
#define RST 4 // Declaration of RESET Pin
Adafruit_ST7789 tft = Adafruit_ST7789(CS, DC, RST);
float p = 3.1415926;
void setup(void) {
Serial.begin(9600);
Serial.print(F("Hello! ST77xx TFT Test"));
tft.init(240, 240 , SPI_MODE2); // Init ST7789 240x240
Serial.println(F("Initialized"));
uint16_t time = millis();
tft.fillScreen(ST77XX_BLACK);
time = millis() - time;
Serial.println(time, DEC);
delay(500);
// large block of text
tft.fillScreen(ST77XX_BLACK);
testdrawtext("Lorem ipsum dolor sit amet, consectetur adipiscing elit. Curabitur adipiscing ante sed nibh tincidunt feugiat. Maecenas enim massa, fringilla sed malesuada et, malesuada sit amet turpis. Sed porttitor neque ut ante pretium vitae malesuada nunc bibendum. Nullam aliquet ultrices massa eu hendrerit. Ut sed nisi lorem. In vestibulum purus a tortor imperdiet posuere. ", ST77XX_WHITE);
delay(1000);
// tft print function!
tftPrintTest();
delay(4000);
// a single pixel
tft.drawPixel(tft.width()/2, tft.height()/2, ST77XX_GREEN);
delay(500);
// line draw test
testlines(ST77XX_YELLOW);
delay(500);
// optimized lines
testfastlines(ST77XX_RED, ST77XX_BLUE);
delay(500);
testdrawrects(ST77XX_GREEN);
delay(500);
testfillrects(ST77XX_YELLOW, ST77XX_MAGENTA);
delay(500);
tft.fillScreen(ST77XX_BLACK);
testfillcircles(10, ST77XX_BLUE);
testdrawcircles(10, ST77XX_WHITE);
delay(500);
testroundrects();
delay(500);
testtriangles();
delay(500);
mediabuttons();
delay(500);
Serial.println("done");
delay(1000);
}
void loop() {
tft.invertDisplay(true);
delay(500);
tft.invertDisplay(false);
delay(500);
}
void testlines(uint16_t color) {
tft.fillScreen(ST77XX_BLACK);
for (int16_t x=0; x < tft.width(); x+=6) {
tft.drawLine(0, 0, x, tft.height()-1, color);
delay(0);
}
for (int16_t y=0; y < tft.height(); y+=6) {
tft.drawLine(0, 0, tft.width()-1, y, color);
delay(0);
}
tft.fillScreen(ST77XX_BLACK);
for (int16_t x=0; x < tft.width(); x+=6) {
tft.drawLine(tft.width()-1, 0, x, tft.height()-1, color);
delay(0);
}
for (int16_t y=0; y < tft.height(); y+=6) {
tft.drawLine(tft.width()-1, 0, 0, y, color);
delay(0);
}
tft.fillScreen(ST77XX_BLACK);
for (int16_t x=0; x < tft.width(); x+=6) {
tft.drawLine(0, tft.height()-1, x, 0, color);
delay(0);
}
for (int16_t y=0; y < tft.height(); y+=6) {
tft.drawLine(0, tft.height()-1, tft.width()-1, y, color);
delay(0);
}
tft.fillScreen(ST77XX_BLACK);
for (int16_t x=0; x < tft.width(); x+=6) {
tft.drawLine(tft.width()-1, tft.height()-1, x, 0, color);
delay(0);
}
for (int16_t y=0; y < tft.height(); y+=6) {
tft.drawLine(tft.width()-1, tft.height()-1, 0, y, color);
delay(0);
}
}
void testdrawtext(char *text, uint16_t color) {
tft.setCursor(0, 0);
tft.setTextColor(color);
tft.setTextWrap(true);
tft.print(text);
}
void testfastlines(uint16_t color1, uint16_t color2) {
tft.fillScreen(ST77XX_BLACK);
for (int16_t y=0; y < tft.height(); y+=5) {
tft.drawFastHLine(0, y, tft.width(), color1);
}
for (int16_t x=0; x < tft.width(); x+=5) {
tft.drawFastVLine(x, 0, tft.height(), color2);
}
}
void testdrawrects(uint16_t color) {
tft.fillScreen(ST77XX_BLACK);
for (int16_t x=0; x < tft.width(); x+=6) {
tft.drawRect(tft.width()/2 -x/2, tft.height()/2 -x/2 , x, x, color);
}
}
void testfillrects(uint16_t color1, uint16_t color2) {
tft.fillScreen(ST77XX_BLACK);
for (int16_t x=tft.width()-1; x > 6; x-=6) {
tft.fillRect(tft.width()/2 -x/2, tft.height()/2 -x/2 , x, x, color1);
tft.drawRect(tft.width()/2 -x/2, tft.height()/2 -x/2 , x, x, color2);
}
}
void testfillcircles(uint8_t radius, uint16_t color) {
for (int16_t x=radius; x < tft.width(); x+=radius*2) {
for (int16_t y=radius; y < tft.height(); y+=radius*2) {
tft.fillCircle(x, y, radius, color);
}
}
}
void testdrawcircles(uint8_t radius, uint16_t color) {
for (int16_t x=0; x < tft.width()+radius; x+=radius*2) {
for (int16_t y=0; y < tft.height()+radius; y+=radius*2) {
tft.drawCircle(x, y, radius, color);
}
}
}
void testtriangles() {
tft.fillScreen(ST77XX_BLACK);
uint16_t color = 0xF800;
int t;
int w = tft.width()/2;
int x = tft.height()-1;
int y = 0;
int z = tft.width();
for(t = 0 ; t <= 15; t++) {
tft.drawTriangle(w, y, y, x, z, x, color);
x-=4;
y+=4;
z-=4;
color+=100;
}
}
void testroundrects() {
tft.fillScreen(ST77XX_BLACK);
uint16_t color = 100;
int i;
int t;
for(t = 0 ; t <= 4; t+=1) {
int x = 0;
int y = 0;
int w = tft.width()-2;
int h = tft.height()-2;
for(i = 0 ; i <= 16; i+=1) {
tft.drawRoundRect(x, y, w, h, 5, color);
x+=2;
y+=3;
w-=4;
h-=6;
color+=1100;
}
color+=100;
}
}
void tftPrintTest() {
tft.setTextWrap(false);
tft.fillScreen(ST77XX_BLACK);
tft.setCursor(0, 30);
tft.setTextColor(ST77XX_RED);
tft.setTextSize(1);
tft.println("Hello World!");
tft.setTextColor(ST77XX_YELLOW);
tft.setTextSize(2);
tft.println("Hello World!");
tft.setTextColor(ST77XX_GREEN);
tft.setTextSize(3);
tft.println("Hello World!");
tft.setTextColor(ST77XX_BLUE);
tft.setTextSize(4);
tft.print(1234.567);
delay(1500);
tft.setCursor(0, 0);
tft.fillScreen(ST77XX_BLACK);
tft.setTextColor(ST77XX_WHITE);
tft.setTextSize(0);
tft.println("Hello World!");
tft.setTextSize(1);
tft.setTextColor(ST77XX_GREEN);
tft.print(p, 6);
tft.println(" Want pi?");
tft.println(" ");
tft.print(8675309, HEX); // print 8,675,309 out in HEX!
tft.println(" Print HEX!");
tft.println(" ");
tft.setTextColor(ST77XX_WHITE);
tft.println("Sketch has been");
tft.println("running for: ");
tft.setTextColor(ST77XX_MAGENTA);
tft.print(millis() / 1000);
tft.setTextColor(ST77XX_WHITE);
tft.print(" seconds.");
}
void mediabuttons() {
// play
tft.fillScreen(ST77XX_BLACK);
tft.fillRoundRect(25, 10, 78, 60, 8, ST77XX_WHITE);
tft.fillTriangle(42, 20, 42, 60, 90, 40, ST77XX_RED);
delay(500);
// pause
tft.fillRoundRect(25, 90, 78, 60, 8, ST77XX_WHITE);
tft.fillRoundRect(39, 98, 20, 45, 5, ST77XX_GREEN);
tft.fillRoundRect(69, 98, 20, 45, 5, ST77XX_GREEN);
delay(500);
// play color
tft.fillTriangle(42, 20, 42, 60, 90, 40, ST77XX_BLUE);
delay(50);
// pause color
tft.fillRoundRect(39, 98, 20, 45, 5, ST77XX_RED);
tft.fillRoundRect(69, 98, 20, 45, 5, ST77XX_RED);
// play color
tft.fillTriangle(42, 20, 42, 60, 90, 40, ST77XX_GREEN);
}