Arduino 2.4" TFT tft.drawChar() working?

I am a beginner in Arduino programming. What I have here is a program (part of a bigger idea) where I try to display a character 'E' on a blue background. There are no compile time errors.

#include "TFTLCD.h"
#include "TouchScreen.h"

#define YP A1
#define XM A2
#define YM 7 
#define XP 6

#define TS_MINX 150
#define TS_MAXX 920
#define TS_MINY 120
#define TS_MAXY 940

TouchScreen ts = TouchScreen(XP,YP,XM,YM,300);

#define LCD_CS A3
#define LCD_CD A2
#define LCD_WR A1
#define LCD_RD A0 
#define LCD_RESET A4

#define BLACK           0x0000
#define BLUE            0x001F
#define RED             0xF800
#define GREEN           0x07E0
#define CYAN            0x07FF
#define MAGENTA         0xF81F
#define YELLOW          0xFFE0 
#define WHITE           0xFFFF

TFTLCD tft(LCD_CS, LCD_CD, LCD_WR, LCD_RD, LCD_RESET);

#define MINPRESSURE 10
#define MAXPRESSURE 1000

void setup()
{
  Serial.begin(9600);
  Serial.println("Simple Calculator");
  
  tft.reset();
  tft.initDisplay();
  tft.fillScreen(BLUE);
  
  tft.drawChar('E',10,10,2,YELLOW);
}

void loop()
{
}

The problem is the character 'E' does not display on the TFT TouchShield (2.4" 240*320). On program execution, I get a blue background but then it goes away which is replaced by a black background with a blue rectangle-kindof patch at the bottom of the screen, a few pixels wide. What could be the problem? Thanks!

Can you get the demo program that came with the library to display text?

I'm not familiar with that actual library. What does the "2" do in tft.drawChar('E',10,10,2,YELLOW);? Can you give us a link to the library or attach it to your reply?

I have attached the TFTLCD and the TouchScreen library files as well. Unfortunately I haven’t referred to any text displaying example prior to writing the code. I just looked at the syntax and started with the program.

As far as the syntax is concerned, the ‘2’ corresponds to the font size of the text character.
Reference : http://www.seeedstudio.com/wiki/2.8’’_TFT_Touch_Shield_V1.0

Thanks for replying MorganS!

Here’s a code (unnecessarily lengthy :frowning: ) that was in the example section. It’s titled graphics test and tests various functions like drawRect(), fillScreen() and so on but doesn’t use drawChar() function. They have used the tft.println() function instead.

#define LCD_CS A3    
#define LCD_CD A2    
#define LCD_WR A1   
#define LCD_RD A0    
// you can also just connect RESET to the arduino RESET pin
#define LCD_RESET A4
//Duemilanove/Diecimila/UNO/etc ('168 and '328 chips) microcontoller:
// Color definitions
#define BLACK           0x0000
#define BLUE            0x001F
#define RED             0xF800
#define GREEN           0x07E0
#define CYAN            0x07FF
#define MAGENTA         0xF81F
#define YELLOW          0xFFE0 
#define WHITE           0xFFFF

#include "TFTLCD.h"

TFTLCD tft(LCD_CS, LCD_CD, LCD_WR, LCD_RD, LCD_RESET);

void setup(void) {
  Serial.begin(9600);
  Serial.println("8 Bit LCD test!");
  
  
  tft.reset();
  

  tft.initDisplay();
  
  testtext(RED);
  delay(2000);
  testlines(CYAN);
  delay(500);
  testfastlines(RED, BLUE);
  delay(500);
  testdrawrects(GREEN);
  delay(500);
  testfillrects(YELLOW, MAGENTA);
  delay(500);
  tft.fillScreen(BLACK);
  testfillcircles(10, MAGENTA);
  testdrawcircles(10, WHITE);
  delay(500); 
  testtriangles();
  delay(500); 
  testfilltriangles();
  delay(500); 
  testRoundRect();
  delay(500); 
  testFillRoundRect();
}

void loop(void) {
  for (uint8_t rotation=0; rotation<4; rotation++) {
    tft.setRotation(rotation); 
    testtext(RED);
    delay(1000);
  }
}



void testFillRoundRect() {
  tft.fillScreen(BLACK);
  
  for (uint16_t x=tft.width(); x > 20 ; x-=6) {
    tft.fillRoundRect(tft.width()/2 -x/2, tft.height()/2 -x/2 , x, x, x/8,  tft.Color565(0, x, 0));
 }
}

void testRoundRect() {
  tft.fillScreen(BLACK);
  
  for (uint16_t x=0; x < tft.width(); x+=6) {
    tft.drawRoundRect(tft.width()/2 -x/2, tft.height()/2 -x/2 , x, x, x/8, tft.Color565(x, 0, 0));
 }
}

void testtriangles() {
  tft.fillScreen(BLACK);
  for (uint16_t i=0; i<tft.width()/2; i+=5) {
    tft.drawTriangle(tft.width()/2, tft.height()/2-i,
                     tft.width()/2-i, tft.height()/2+i,
                     tft.width()/2+i, tft.height()/2+i, tft.Color565(0, 0, i));
  }
}

void testfilltriangles() {
  tft.fillScreen(BLACK);
  
  for (uint16_t i=tft.width()/2; i>10; i-=5) {
    tft.fillTriangle(tft.width()/2, tft.height()/2-i,
                     tft.width()/2-i, tft.height()/2+i,
                     tft.width()/2+i, tft.height()/2+i, 
                     tft.Color565(0, i, i));
    tft.drawTriangle(tft.width()/2, tft.height()/2-i,
                     tft.width()/2-i, tft.height()/2+i,
                     tft.width()/2+i, tft.height()/2+i, tft.Color565(i, i, 0));    
  }
}
void testtext(uint16_t color) {
  tft.fillScreen(BLACK);
  tft.setCursor(0, 20);
  tft.setTextColor(color);
  tft.setTextSize(1);
  tft.println("Hello World!");
  tft.setTextSize(2);
  tft.println(1234.56);
  tft.setTextSize(3);
  tft.println(0xDEADBEEF, HEX);
}

void testfillcircles(uint8_t radius, uint16_t color) {
  for (uint16_t x=radius; x < tft.width(); x+=radius*2) {
    for (uint16_t y=radius; y < tft.height(); y+=radius*2) {
      tft.fillCircle(x, y, radius, color);
    }
  }  
}

void testdrawcircles(uint8_t radius, uint16_t color) {
  for (uint16_t x=0; x < tft.width()+radius; x+=radius*2) {
    for (uint16_t y=0; y < tft.height()+radius; y+=radius*2) {
      tft.drawCircle(x, y, radius, color);
    }
  }  
}


void testfillrects(uint16_t color1, uint16_t color2) {
 tft.fillScreen(BLACK);
 for (uint16_t x=tft.width()-1; x > 6; x-=6) {
   //Serial.println(x, DEC);
   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 testdrawrects(uint16_t color) {
 tft.fillScreen(BLACK);
 for (uint16_t x=0; x < tft.width(); x+=6) {
   tft.drawRect(tft.width()/2 -x/2, tft.height()/2 -x/2 , x, x, color);
 }
}

void testfastlines(uint16_t color1, uint16_t color2) {
   tft.fillScreen(BLACK);
   for (uint16_t y=0; y < tft.height(); y+=5) {
     tft.drawHorizontalLine(0, y, tft.width(), color1);
   }
   for (uint16_t x=0; x < tft.width(); x+=5) {
     tft.drawVerticalLine(x, 0, tft.height(), color2);
   }
  
}

void testlines(uint16_t color) {
   tft.fillScreen(BLACK);
   for (uint16_t x=0; x < tft.width(); x+=6) {
     tft.drawLine(0, 0, x, tft.height()-1, color);
   }
   for (uint16_t y=0; y < tft.height(); y+=6) {
     tft.drawLine(0, 0, tft.width()-1, y, color);
   }
   
   tft.fillScreen(BLACK);
   for (uint16_t x=0; x < tft.width(); x+=6) {
     tft.drawLine(tft.width()-1, 0, x, tft.height()-1, color);
   }
   for (uint16_t y=0; y < tft.height(); y+=6) {
     tft.drawLine(tft.width()-1, 0, 0, y, color);
   }
   
   tft.fillScreen(BLACK);
   for (uint16_t x=0; x < tft.width(); x+=6) {
     tft.drawLine(0, tft.height()-1, x, 0, color);
   }
   for (uint16_t y=0; y < tft.height(); y+=6) {
     tft.drawLine(0, tft.height()-1, tft.width()-1, y, color);
   }

   tft.fillScreen(BLACK);
   for (uint16_t x=0; x < tft.width(); x+=6) {
     tft.drawLine(tft.width()-1, tft.height()-1, x, 0, color);
   }
   for (uint16_t y=0; y < tft.height(); y+=6) {
     tft.drawLine(tft.width()-1, tft.height()-1, 0, y, color);
   }
}


void testBars() {
  uint16_t i,j;
  for(i=0; i < tft.height(); i++)
  {
    for(j=0; j < tft.width(); j++)
    {
      if(i>279) tft.writeData(WHITE);
      else if(i>239) tft.writeData(BLUE);
      else if(i>199) tft.writeData(GREEN);
      else if(i>159) tft.writeData(CYAN);
      else if(i>119) tft.writeData(RED);
      else if(i>79) tft.writeData(MAGENTA);
      else if(i>39) tft.writeData(YELLOW);
      else tft.writeData(BLACK);
    }
  }
}

glcdfont.c (8.14 KB)

TFTLCD.cpp (23.3 KB)

TFTLCD.h (5.22 KB)

TouchScreen.cpp (5.28 KB)

TouchScreen.h (725 Bytes)