TFT LCD Screen Module:
Before we actually dive into the project it is important to know, how this 2.4” TFT LCD Module works and what are the types present in it. Let us take a look at the pinouts of this 2.4” TFT LCD screen module.
As you can see there are 28 pins which will perfectly fit into any Arduino Uno / Arduino Mega Board. A small classification of these pins is given in the table below
As you can see the pins can be classified in to four main classifications such as LCD Command Pins, LCD Data Pins, SD Card Pins and Power Pins, We need not know much about the detailed working of these pins since they will be take care by our Arduino Library.
You can also find an SD card slot at the bottom of the module shown above, which can be used to load an SD card with bmp image files, and these images can be displayed in our TFT LCD screen using the Arduino Program.
Another important thing to note is your Interface IC. There are many types of TFT modules available in the market starting from the original Adafruit TFT LCD module to cheap Chinese clones. A program which works perfectly for your Adafruit shield might not work the same for Chinese breakout boards. So, it is very important to know which types of LCD display your are holding in hand. This detail has to be obtained from the vendor. If you are having a cheap clone like mine then it is most probably using the ili9341 driver IC. You can follow this TFT LCD interfacing with Arduino tutorial to try out some basic example programs and get comfortable with the LCD screen.
Calibrating the TFT LCD Screen for Touch Screen:
If you planning to use the touch screen function of your TFT LCD module, then you have to calibrate it to make it work properly. A LCD screen without calibration might work unlikely, for instance you might touch at one place and the TFT might respond for a touch at some other place. These calibrations results will not be similar for all boards and hence you are left on your own to do this.
The best way to calibrate is to use the calibration example program (comes with library) or use the serial monitor to detect your error. However for this project since the size of buttons is large calibration should not be a big problem and I will also explain how you can calibrate your screen under the programming section below.
Interfacing with Arduino:
The 2.4” TFT LCD screen is a perfect Arduino Shield. You can directly push the LCD screen on top of the Arduino Uno and it will perfectly match with the pins and slid in through. However, as matters of safety cover the Programming terminal of your Arduino UNO with a small insulation tape, just in case if the terminal comes in contact with your TFT LCD screen. The LCD assembled on UNO will look something like this below.
Code:
/*______Import Libraries_______*/
#include <SPFD5408_Adafruit_GFX.h> // Core graphics library
#include <SPFD5408_Adafruit_TFTLCD.h> // Hardware-specific library
#include <SPFD5408_TouchScreen.h>
/*______End of Libraries_______*/
/*______Define LCD pins (I have asigned the default values)_______*/
#define YP A1 // must be an analog pin, use “An” notation!
#define XM A2 // must be an analog pin, use “An” notation!
#define YM 7 // can be a digital pin
#define XP 6 // can be a digital pin
#define LCD_CS A3
#define LCD_CD A2
#define LCD_WR A1
#define LCD_RD A0
#define LCD_RESET A4
/*_______End of defanitions______*/
/*______Assign names to colors and pressure_______*/
#define WHITE 0x0000 //Black->White
#define YELLOW 0x001F //Blue->Yellow
#define CYAN 0xF800 //Red->Cyan
#define PINK 0x07E0 //Green-> Pink
#define RED 0x07FF //Cyan -> Red
#define GREEN 0xF81F //Pink -> Green
#define BLUE 0xFFE0 //Yellow->Blue
#define BLACK 0xFFFF //White-> Black
#define MINPRESSURE 10
#define MAXPRESSURE 1000
/*_______Assigned______*/
/*____Calibrate TFT LCD_____*/
#define TS_MINX 125
#define TS_MINY 85
#define TS_MAXX 965
#define TS_MAXY 905
/*______End of Calibration______*/
TouchScreen ts = TouchScreen(XP, YP, XM, YM, 300); //300 is the sensitivity
Adafruit_TFTLCD tft(LCD_CS, LCD_CD, LCD_WR, LCD_RD, LCD_RESET); //Start communication with LCD
String symbol[4][4] = {
{ “7”, “8”, “9”, “/” },
{ “4”, “5”, “6”, “*” },
{ “1”, “2”, “3”, “-” },
{ “C”, “0”, “=”, “+” }
};
int X,Y;
long Num1,Num2,Number;
char action;
boolean result = false;
void setup() {
Serial.begin(9600); //Use serial monitor for debugging
tft.reset(); //Always reset at start
tft.begin(0x9341); // My LCD uses LIL9341 Interface driver IC
tft.setRotation(2); // I just roated so that the power jack faces up – optional
tft.fillScreen(WHITE);
IntroScreen();
draw_BoxNButtons();
}
void loop() {
TSPoint p = waitTouch();
X = p.y; Y = p.x;
// Serial.print(X); Serial.print(‘,’); Serial.println(Y);// + ” ” + Y);
DetectButtons();
if (result==true)
CalculateResult();
DisplayResult();
delay(300);
}
TSPoint waitTouch() {
TSPoint p;
do {
p = ts.getPoint();
pinMode(XM, OUTPUT);
pinMode(YP, OUTPUT);
} while((p.z < MINPRESSURE )|| (p.z > MAXPRESSURE));
p.x = map(p.x, TS_MINX, TS_MAXX, 0, 320);
p.y = map(p.y, TS_MINY, TS_MAXY, 0, 240);;
return p;
}
void DetectButtons()
{
if (X<50 && X>0) //Detecting Buttons on Column 1
{
if (Y>0 && Y<85) //If cancel Button is pressed
{Serial.println (“Button Cancel”); Number=Num1=Num2=0; result=false;}
if (Y>85 && Y<140) //If Button 1 is pressed
{Serial.println (“Button 1”);
if (Number==0)
Number=1;
else
Number = (Number*10) + 1; //Pressed twice
}
if (Y>140 && Y<192) //If Button 4 is pressed
{Serial.println (“Button 4”);
if (Number==0)
Number=4;
else
Number = (Number*10) + 4; //Pressed twice
}
if (Y>192 && Y<245) //If Button 7 is pressed
{Serial.println (“Button 7”);
if (Number==0)
Number=7;
else
Number = (Number*10) + 7; //Pressed twice
}
}
if (X<105 && X>50) //Detecting Buttons on Column 2
{
if (Y>0 && Y<85)
{Serial.println (“Button 0”); //Button 0 is Pressed
if (Number==0)
Number=0;
else
Number = (Number*10) + 0; //Pressed twice
}
if (Y>85 && Y<140)
{Serial.println (“Button 2”);
if (Number==0)
Number=2;
else
Number = (Number*10) + 2; //Pressed twice
}
if (Y>140 && Y<192)
{Serial.println (“Button 5”);
if (Number==0)
Number=5;
else
Number = (Number*10) + 5; //Pressed twic
}
if (Y>192 && Y<245)
{Serial.println (“Button 8”);
if (Number==0)
Number=8;
else
Number = (Number*10) + 8; //Pressed twic
}
}
if (X<165 && X>105) //Detecting Buttons on Column 3
{
if (Y>0 && Y<85)
{Serial.println (“Button Equal”);
Num2=Number;
result = true;
}
if (Y>85 && Y<140)
{Serial.println (“Button 3”);
if (Number==0)
Number=3;
else
Number = (Number*10) + 3; //Pressed twice
}
if (Y>140 && Y<192)
{Serial.println (“Button 6”);
if (Number==0)
Number=6;
else
Number = (Number*10) + 6; //Pressed twice
}
if (Y>192 && Y<245)
{Serial.println (“Button 9”);
if (Number==0)
Number=9;
else
Number = (Number*10) + 9; //Pressed twice
}
}
if (X<213 && X>165) //Detecting Buttons on Column 3
{
Num1 = Number;
Number =0;
tft.setCursor(200, 20);
tft.setTextColor(RED);
if (Y>0 && Y<85)
{Serial.println (“Addition”); action = 1; tft.println(‘+’);}
if (Y>85 && Y<140)
{Serial.println (“Subtraction”); action = 2; tft.println(‘-‘);}
if (Y>140 && Y<192)
{Serial.println (“Multiplication”); action = 3; tft.println(‘*’);}
if (Y>192 && Y<245)
{Serial.println (“Devesion”); action = 4; tft.println(‘/’);}
delay(300);
}
}
void CalculateResult()
{
if (action==1)
Number = Num1+Num2;
if (action==2)
Number = Num1-Num2;
if (action==3)
Number = Num1*Num2;
if (action==4)
Number = Num1/Num2;
}
void DisplayResult()
{
tft.fillRect(0, 0, 240, 80, CYAN); //clear result box
tft.setCursor(10, 20);
tft.setTextSize(4);
tft.setTextColor(BLACK);
tft.println(Number); //update new value
}
void IntroScreen()
{
tft.setCursor (55, 120);
tft.setTextSize (3);
tft.setTextColor(RED);
tft.println(“ARDUINO”);
tft.setCursor (30, 160);
tft.println(“CALCULATOR”);
tft.setCursor (30, 220);
tft.setTextSize (2);
tft.setTextColor(BLUE);
tft.println(“-Circut Digest”);
delay(1800);
}
void draw_BoxNButtons()
{
//Draw the Result Box
tft.fillRect(0, 0, 240, 80, CYAN);
//Draw First Column
tft.fillRect (0,260,60,60,RED);
tft.fillRect (0,200,60,60,BLACK);
tft.fillRect (0,140,60,60,BLACK);
tft.fillRect (0,80,60,60,BLACK);
//Draw Third Column
tft.fillRect (120,260,60,60,GREEN);
tft.fillRect (120,200,60,60,BLACK);
tft.fillRect (120,140,60,60,BLACK);
tft.fillRect (120,80,60,60,BLACK);
//Draw Secound & Fourth Column
for (int b=260; b>=80; b-=60)
{ tft.fillRect (180,b,60,60,BLUE);
tft.fillRect (60,b,60,60,BLACK);}
//Draw Horizontal Lines
for (int h=80; h<=320; h+=60)
tft.drawFastHLine(0, h, 240, WHITE);
//Draw Vertical Lines
for (int v=0; v<=240; v+=60)
tft.drawFastVLine(v, 80, 240, WHITE);
//Display keypad lables
for (int j=0;j<4;j++) {
for (int i=0;i<4;i++) {
tft.setCursor(22 + (60*i), 100 + (60*j));
tft.setTextSize(3);
tft.setTextColor(WHITE);
tft.println(symbol[j][i]);
}
}
}
Application:
- mobile devices,
- appliance,
- medical devices,
- instrumentation,
- Aircraft and certainly computer displaydevices as well as TV’s.
Reference:
https://create.arduino.cc/projecthub/electropeak/arduino-2-4-touch-screen-lcd-shield-tutorial-fe6f05
https://www.instructables.com/id/How-to-use-24-inch-TFT-LCD-SPFD5408-with-Arduino-U/