Pocket-sized Drawing Tablet | Arduino

In this instructable I will tech you how to make a pocket-sized Arduino powered drawing tablet at home.

All you need is an Arduino Uno of Mega,

and an arduino tft screen.

I powered mine with a nine volt battery.

Simply push your tft screen into place on top of the arduino.

Now, plug your arduino into your computer. Open up the arduino ide and copy this code into it then upload:

#include // Core graphics library #include // Hardware-specific library #include

#if defined(__SAM3X8E__) #undef __FlashStringHelper::F(string_literal) #define F(string_literal) string_literal #endif

// When using the BREAKOUT BOARD only, use these 8 data lines to the LCD: // For the Arduino Uno, Duemilanove, Diecimila, etc.: // D0 connects to digital pin 8 (Notice these are // D1 connects to digital pin 9 NOT in order!) // D2 connects to digital pin 2 // D3 connects to digital pin 3 // D4 connects to digital pin 4 // D5 connects to digital pin 5 // D6 connects to digital pin 6 // D7 connects to digital pin 7

// For the Arduino Mega, use digital pins 22 through 29 // (on the 2-row header at the end of the board). // D0 connects to digital pin 22 // D1 connects to digital pin 23 // D2 connects to digital pin 24 // D3 connects to digital pin 25 // D4 connects to digital pin 26 // D5 connects to digital pin 27 // D6 connects to digital pin 28 // D7 connects to digital pin 29

// For the Arduino Due, use digital pins 33 through 40 // (on the 2-row header at the end of the board). // D0 connects to digital pin 33 // D1 connects to digital pin 34 // D2 connects to digital pin 35 // D3 connects to digital pin 36 // D4 connects to digital pin 37 // D5 connects to digital pin 38 // D6 connects to digital pin 39 // D7 connects to digital pin 40 /* #define YP 9 // must be an analog pin, use "An" notation! #define XM 8 // must be an analog pin, use "An" notation! #define YM A2 // can be a digital pin #define XP A3 // can be a digital pin */

#define YP A3 // must be an analog pin, use "An" notation! #define XM A2 // must be an analog pin, use "An" notation! #define YM 9 // can be a digital pin #define XP 8 // can be a digital pin /* #define TS_MINX 50 #define TS_MAXX 920

#define TS_MINY 100 #define TS_MAXY 940 */ //Touch For New ILI9341 TP #define TS_MINX 120 #define TS_MAXX 900

#define TS_MINY 70 #define TS_MAXY 920

// For better pressure precision, we need to know the resistance // between X+ and X- Use any multimeter to read it // For the one we're using, its 300 ohms across the X plate TouchScreen ts = TouchScreen(XP, YP, XM, YM, 300);

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

// Assign human-readable names to some common 16-bit color values: #define BLACK 0x0000 #define BLUE 0x001F #define RED 0xF800 #define GREEN 0x07E0 #define CYAN 0x07FF #define MAGENTA 0xF81F #define YELLOW 0xFFE0 #define WHITE 0xFFFF

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

#define BOXSIZE 40 #define PENRADIUS 3 int oldcolor, currentcolor;

void setup(void) { Serial.begin(9600); Serial.println(F("Paint!")); tft.reset(); uint16_t identifier = tft.readID(); if(identifier == 0x9325) { Serial.println(F("Found ILI9325 LCD driver")); } else if(identifier == 0x9328) { Serial.println(F("Found ILI9328 LCD driver")); } else if(identifier == 0x4535) { Serial.println(F("Found LGDP4535 LCD driver")); }else if(identifier == 0x7575) { Serial.println(F("Found HX8347G LCD driver")); } else if(identifier == 0x9341) { Serial.println(F("Found ILI9341 LCD driver")); } else if(identifier == 0x8357) { Serial.println(F("Found HX8357D LCD driver")); } else if(identifier==0x0101) { identifier=0x9341; Serial.println(F("Found 0x9341 LCD driver")); }else { Serial.print(F("Unknown LCD driver chip: ")); Serial.println(identifier, HEX); Serial.println(F("If using the Elegoo 2.8\" TFT Arduino shield, the line:")); Serial.println(F(" #define USE_Elegoo_SHIELD_PINOUT")); Serial.println(F("should appear in the library header (Elegoo_TFT.h).")); Serial.println(F("If using the breakout board, it should NOT be #defined!")); Serial.println(F("Also if using the breakout, double-check that all wiring")); Serial.println(F("matches the tutorial.")); identifier=0x9341; }

tft.begin(identifier); tft.setRotation(2);

tft.fillScreen(BLACK);

tft.fillRect(0, 0, BOXSIZE, BOXSIZE, RED); tft.fillRect(BOXSIZE, 0, BOXSIZE, BOXSIZE, YELLOW); tft.fillRect(BOXSIZE*2, 0, BOXSIZE, BOXSIZE, GREEN); tft.fillRect(BOXSIZE*3, 0, BOXSIZE, BOXSIZE, CYAN); tft.fillRect(BOXSIZE*4, 0, BOXSIZE, BOXSIZE, BLUE); tft.fillRect(BOXSIZE*5, 0, BOXSIZE, BOXSIZE, MAGENTA); // tft.fillRect(BOXSIZE*6, 0, BOXSIZE, BOXSIZE, WHITE); tft.drawRect(0, 0, BOXSIZE, BOXSIZE, WHITE); currentcolor = RED; pinMode(13, OUTPUT); }

#define MINPRESSURE 10 #define MAXPRESSURE 1000

void loop() { digitalWrite(13, HIGH); TSPoint p = ts.getPoint(); digitalWrite(13, LOW);

// if sharing pins, you'll need to fix the directions of the touchscreen pins //pinMode(XP, OUTPUT); pinMode(XM, OUTPUT); pinMode(YP, OUTPUT); //pinMode(YM, OUTPUT);

// we have some minimum pressure we consider 'valid' // pressure of 0 means no pressing!

if (p.z > MINPRESSURE && p.z < MAXPRESSURE) { /* Serial.print("X = "); Serial.print(p.x); Serial.print("\tY = "); Serial.print(p.y); Serial.print("\tPressure = "); Serial.println(p.z); */ if (p.y < (TS_MINY-5)) { Serial.println("erase"); // press the bottom of the screen to erase tft.fillRect(0, BOXSIZE, tft.width(), tft.height()-BOXSIZE, BLACK); } // scale from 0->1023 to tft.width p.x = map(p.x, TS_MINX, TS_MAXX, tft.width(), 0); //p.x = tft.width()-map(p.x, TS_MINX, TS_MAXX, tft.width(), 0); p.y = (tft.height()-map(p.y, TS_MINY, TS_MAXY, tft.height(), 0)); //p.y = map(p.y, TS_MINY, TS_MAXY, tft.height(), 0); /* Serial.print("("); Serial.print(p.x); Serial.print(", "); Serial.print(p.y); Serial.println(")"); */ if (p.y < BOXSIZE) { oldcolor = currentcolor;

if (p.x < BOXSIZE) { currentcolor = RED; tft.drawRect(0, 0, BOXSIZE, BOXSIZE, WHITE); } else if (p.x < BOXSIZE*2) { currentcolor = YELLOW; tft.drawRect(BOXSIZE, 0, BOXSIZE, BOXSIZE, WHITE); } else if (p.x < BOXSIZE*3) { currentcolor = GREEN; tft.drawRect(BOXSIZE*2, 0, BOXSIZE, BOXSIZE, WHITE); } else if (p.x < BOXSIZE*4) { currentcolor = CYAN; tft.drawRect(BOXSIZE*3, 0, BOXSIZE, BOXSIZE, WHITE); } else if (p.x < BOXSIZE*5) { currentcolor = BLUE; tft.drawRect(BOXSIZE*4, 0, BOXSIZE, BOXSIZE, WHITE); } else if (p.x < BOXSIZE*6) { currentcolor = MAGENTA; tft.drawRect(BOXSIZE*5, 0, BOXSIZE, BOXSIZE, WHITE); }

if (oldcolor != currentcolor) { if (oldcolor == RED) tft.fillRect(0, 0, BOXSIZE, BOXSIZE, RED); if (oldcolor == YELLOW) tft.fillRect(BOXSIZE, 0, BOXSIZE, BOXSIZE, YELLOW); if (oldcolor == GREEN) tft.fillRect(BOXSIZE*2, 0, BOXSIZE, BOXSIZE, GREEN); if (oldcolor == CYAN) tft.fillRect(BOXSIZE*3, 0, BOXSIZE, BOXSIZE, CYAN); if (oldcolor == BLUE) tft.fillRect(BOXSIZE*4, 0, BOXSIZE, BOXSIZE, BLUE); if (oldcolor == MAGENTA) tft.fillRect(BOXSIZE*5, 0, BOXSIZE, BOXSIZE, MAGENTA); } } if (((p.y-PENRADIUS) > BOXSIZE) && ((p.y+PENRADIUS) < tft.height())) { tft.fillCircle(p.x, p.y, PENRADIUS, currentcolor); } } }

If that uploads correctly, you should have a working drawing tablet! Congratulations!! 😀