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Working with STM32F429-discovery Display Part 2: LCD Initializing

Posted in Embedded Systems, LCD, Peripheral Drivers, STM32

In the previous guide (here), we took a look at STM32F429 Discovery and it’s features and the environment has been setup. In this guide, we shall cover the following:

  • Delay initializing.
  • LCD initializing.
  • Support functions.
  • Code
  • Results.

1. Delay initializing:

We start off by creating new header file with name of delay.h.

Within the header file, include the header guard:

#ifndef DELAY_H_
#define DELAY_H_



#endif /* DELAY_H_ */

Include the following header file:

#include "stdint.h"

Declare the following functions:

void delay_init(uint32_t freq);
uint64_t millis();
void delay(uint32_t time);

Hence, the entire header file as following:

#ifndef DELAY_H_
#define DELAY_H_

#include "stdint.h"

void delay_init(uint32_t freq);
uint64_t millis();
void delay(uint32_t time);




#endif /* DELAY_H_ */

Now. Create new source code with name of delay.c.

Within the source file:

#include "delay.h"
#include "stm32f4xx.h"



#define	CTRL_ENABLE					(1U<<0)
#define CTRL_CLKSRC					(1U<<2)
#define CTRL_COUNTFLAG				(1U<<16)
#define CTRL_TICKINT				(1U<<1)


volatile uint64_t mil;

void delay_init(uint32_t freq)
{

	SysTick->LOAD  = (freq/1000) - 1;

	/*Clear systick current value register */
	SysTick->VAL = 0;

	/*Enable systick and select internal clk src*/
	SysTick->CTRL = CTRL_ENABLE | CTRL_CLKSRC ;

	/*Enable systick interrupt*/
	SysTick->CTRL  |= CTRL_TICKINT;

}



uint64_t millis()
	{
	__disable_irq();
	uint64_t ml=mil;
	__enable_irq();
	return ml;
	}



void delay(uint32_t time)
	{

	uint64_t start=millis();
	while((millis() - start) < time);
	}

void SysTick_Handler(void)
{
	mil++;

}

How to implement the systick interrupt, check this guide.

Thats all for the delay part. Next, the LCD initialization.

2. LCD Initializing:

Create new header file with name of ILI9341.h.

Include the header guard as following:

#ifndef ILI9341_H_
#define ILI9341_H_



#endif

Within the header file, include the following header files:

//List of includes
#include <stdbool.h>
#include "delay.h"
#include <stdint.h>
#include <math.h>

Now, we shall declare list of symbolics, we start off by the dimensions of the LCD as following:

//LCD dimensions defines
#define ILI9341_WIDTH       240
#define ILI9341_HEIGHT      320

Total pixels:

#define ILI9341_PIXEL_COUNT	ILI9341_WIDTH * ILI9341_HEIGHT

List of LCD commands:

//ILI9341 LCD commands
#define ILI9341_RESET			 		    0x01
#define ILI9341_SLEEP_OUT		  			0x11
#define ILI9341_GAMMA			    		0x26
#define ILI9341_DISPLAY_OFF					0x28
#define ILI9341_DISPLAY_ON					0x29
#define ILI9341_COLUMN_ADDR					0x2A
#define ILI9341_PAGE_ADDR			  		0x2B
#define ILI9341_GRAM				    	0x2C
#define ILI9341_TEARING_OFF					0x34
#define ILI9341_TEARING_ON					0x35
#define ILI9341_DISPLAY_INVERSION			0xb4
#define ILI9341_MAC			        		0x36
#define ILI9341_PIXEL_FORMAT    			0x3A
#define ILI9341_WDB			    	  		0x51
#define ILI9341_WCD				      		0x53
#define ILI9341_RGB_INTERFACE   			0xB0
#define ILI9341_FRC					    	0xB1
#define ILI9341_BPC					    	0xB5
#define ILI9341_DFC				 	    	0xB6
#define ILI9341_Entry_Mode_Set				0xB7
#define ILI9341_POWER1						0xC0
#define ILI9341_POWER2						0xC1
#define ILI9341_VCOM1						0xC5
#define ILI9341_VCOM2						0xC7
#define ILI9341_POWERA						0xCB
#define ILI9341_POWERB						0xCF
#define ILI9341_PGAMMA						0xE0
#define ILI9341_NGAMMA						0xE1
#define ILI9341_DTCA						0xE8
#define ILI9341_DTCB						0xEA
#define ILI9341_POWER_SEQ					0xED
#define ILI9341_3GAMMA_EN					0xF2
#define ILI9341_INTERFACE					0xF6
#define ILI9341_PRC				   	  		0xF7
#define ILI9341_VERTICAL_SCROLL 			0x33

#define ILI9341_MEMCONTROL         	0x36
#define ILI9341_MADCTL_MY  			0x80
#define ILI9341_MADCTL_MX  			0x40
#define ILI9341_MADCTL_MV  			0x20
#define ILI9341_MADCTL_ML  			0x10
#define ILI9341_MADCTL_RGB 			0x00
#define ILI9341_MADCTL_BGR 			0x08
#define ILI9341_MADCTL_MH  			0x04

List of colors:

//List of colors
#define COLOR_BLACK           0x0000  
#define COLOR_NAVY            0x000F      
#define COLOR_DGREEN          0x03E0     
#define COLOR_DCYAN           0x03EF  
#define COLOR_MAROON          0x7800 
#define COLOR_PURPLE          0x780F
#define COLOR_OLIVE           0x7BE0     
#define COLOR_LGRAY           0xC618      
#define COLOR_DGRAY           0x7BEF    
#define COLOR_BLUE            0x001F    
#define COLOR_BLUE2			  0x051D
#define COLOR_GREEN           0x07E0      
#define COLOR_GREEN2		  0xB723
#define COLOR_GREEN3		  0x8000
#define COLOR_CYAN            0x07FF   
#define COLOR_RED             0xF800    
#define COLOR_MAGENTA         0xF81F    
#define COLOR_YELLOW          0xFFE0   
#define COLOR_WHITE           0xFFFF     
#define COLOR_ORANGE          0xFD20     
#define COLOR_GREENYELLOW     0xAFE5     
#define COLOR_BROWN 		  0XBC40 
#define COLOR_BRRED 	 	  0XFC07

Required macros:

//Functions defines Macros
#define swap(a, b) { int16_t t = a; a = b; b = t; }
#define min(a,b) (((a)<(b))?(a):(b))

Font declarations:

static //Text simple font array (You can your own font)
const unsigned char Font[] = {
	0x00, 0x00, 0x00, 0x00, 0x00,
	0x3E, 0x5B, 0x4F, 0x5B, 0x3E,
	0x3E, 0x6B, 0x4F, 0x6B, 0x3E,
	0x1C, 0x3E, 0x7C, 0x3E, 0x1C,
	0x18, 0x3C, 0x7E, 0x3C, 0x18,
	0x1C, 0x57, 0x7D, 0x57, 0x1C,
	0x1C, 0x5E, 0x7F, 0x5E, 0x1C,
	0x00, 0x18, 0x3C, 0x18, 0x00,
	0xFF, 0xE7, 0xC3, 0xE7, 0xFF,
	0x00, 0x18, 0x24, 0x18, 0x00,
	0xFF, 0xE7, 0xDB, 0xE7, 0xFF,
	0x30, 0x48, 0x3A, 0x06, 0x0E,
	0x26, 0x29, 0x79, 0x29, 0x26,
	0x40, 0x7F, 0x05, 0x05, 0x07,
	0x40, 0x7F, 0x05, 0x25, 0x3F,
	0x5A, 0x3C, 0xE7, 0x3C, 0x5A,
	0x7F, 0x3E, 0x1C, 0x1C, 0x08,
	0x08, 0x1C, 0x1C, 0x3E, 0x7F,
	0x14, 0x22, 0x7F, 0x22, 0x14,
	0x5F, 0x5F, 0x00, 0x5F, 0x5F,
	0x06, 0x09, 0x7F, 0x01, 0x7F,
	0x00, 0x66, 0x89, 0x95, 0x6A,
	0x60, 0x60, 0x60, 0x60, 0x60,
	0x94, 0xA2, 0xFF, 0xA2, 0x94,
	0x08, 0x04, 0x7E, 0x04, 0x08,
	0x10, 0x20, 0x7E, 0x20, 0x10,
	0x08, 0x08, 0x2A, 0x1C, 0x08,
	0x08, 0x1C, 0x2A, 0x08, 0x08,
	0x1E, 0x10, 0x10, 0x10, 0x10,
	0x0C, 0x1E, 0x0C, 0x1E, 0x0C,
	0x30, 0x38, 0x3E, 0x38, 0x30,
	0x06, 0x0E, 0x3E, 0x0E, 0x06,
	0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x5F, 0x00, 0x00,
	0x00, 0x07, 0x00, 0x07, 0x00,
	0x14, 0x7F, 0x14, 0x7F, 0x14,
	0x24, 0x2A, 0x7F, 0x2A, 0x12,
	0x23, 0x13, 0x08, 0x64, 0x62,
	0x36, 0x49, 0x56, 0x20, 0x50,
	0x00, 0x08, 0x07, 0x03, 0x00,
	0x00, 0x1C, 0x22, 0x41, 0x00,
	0x00, 0x41, 0x22, 0x1C, 0x00,
	0x2A, 0x1C, 0x7F, 0x1C, 0x2A,
	0x08, 0x08, 0x3E, 0x08, 0x08,
	0x00, 0x80, 0x70, 0x30, 0x00,
	0x08, 0x08, 0x08, 0x08, 0x08,
	0x00, 0x00, 0x60, 0x60, 0x00,
	0x20, 0x10, 0x08, 0x04, 0x02,
	0x3E, 0x51, 0x49, 0x45, 0x3E,
	0x00, 0x42, 0x7F, 0x40, 0x00,
	0x72, 0x49, 0x49, 0x49, 0x46,
	0x21, 0x41, 0x49, 0x4D, 0x33,
	0x18, 0x14, 0x12, 0x7F, 0x10,
	0x27, 0x45, 0x45, 0x45, 0x39,
	0x3C, 0x4A, 0x49, 0x49, 0x31,
	0x41, 0x21, 0x11, 0x09, 0x07,
	0x36, 0x49, 0x49, 0x49, 0x36,
	0x46, 0x49, 0x49, 0x29, 0x1E,
	0x00, 0x00, 0x14, 0x00, 0x00,
	0x00, 0x40, 0x34, 0x00, 0x00,
	0x00, 0x08, 0x14, 0x22, 0x41,
	0x14, 0x14, 0x14, 0x14, 0x14,
	0x00, 0x41, 0x22, 0x14, 0x08,
	0x02, 0x01, 0x59, 0x09, 0x06,
	0x3E, 0x41, 0x5D, 0x59, 0x4E,
	0x7C, 0x12, 0x11, 0x12, 0x7C,
	0x7F, 0x49, 0x49, 0x49, 0x36,
	0x3E, 0x41, 0x41, 0x41, 0x22,
	0x7F, 0x41, 0x41, 0x41, 0x3E,
	0x7F, 0x49, 0x49, 0x49, 0x41,
	0x7F, 0x09, 0x09, 0x09, 0x01,
	0x3E, 0x41, 0x41, 0x51, 0x73,
	0x7F, 0x08, 0x08, 0x08, 0x7F,
	0x00, 0x41, 0x7F, 0x41, 0x00,
	0x20, 0x40, 0x41, 0x3F, 0x01,
	0x7F, 0x08, 0x14, 0x22, 0x41,
	0x7F, 0x40, 0x40, 0x40, 0x40,
	0x7F, 0x02, 0x1C, 0x02, 0x7F,
	0x7F, 0x04, 0x08, 0x10, 0x7F,
	0x3E, 0x41, 0x41, 0x41, 0x3E,
	0x7F, 0x09, 0x09, 0x09, 0x06,
	0x3E, 0x41, 0x51, 0x21, 0x5E,
	0x7F, 0x09, 0x19, 0x29, 0x46,
	0x26, 0x49, 0x49, 0x49, 0x32,
	0x03, 0x01, 0x7F, 0x01, 0x03,
	0x3F, 0x40, 0x40, 0x40, 0x3F,
	0x1F, 0x20, 0x40, 0x20, 0x1F,
	0x3F, 0x40, 0x38, 0x40, 0x3F,
	0x63, 0x14, 0x08, 0x14, 0x63,
	0x03, 0x04, 0x78, 0x04, 0x03,
	0x61, 0x59, 0x49, 0x4D, 0x43,
	0x00, 0x7F, 0x41, 0x41, 0x41,
	0x02, 0x04, 0x08, 0x10, 0x20,
	0x00, 0x41, 0x41, 0x41, 0x7F,
	0x04, 0x02, 0x01, 0x02, 0x04,
	0x40, 0x40, 0x40, 0x40, 0x40,
	0x00, 0x03, 0x07, 0x08, 0x00,
	0x20, 0x54, 0x54, 0x78, 0x40,
	0x7F, 0x28, 0x44, 0x44, 0x38,
	0x38, 0x44, 0x44, 0x44, 0x28,
	0x38, 0x44, 0x44, 0x28, 0x7F,
	0x38, 0x54, 0x54, 0x54, 0x18,
	0x00, 0x08, 0x7E, 0x09, 0x02,
	0x18, 0xA4, 0xA4, 0x9C, 0x78,
	0x7F, 0x08, 0x04, 0x04, 0x78,
	0x00, 0x44, 0x7D, 0x40, 0x00,
	0x20, 0x40, 0x40, 0x3D, 0x00,
	0x7F, 0x10, 0x28, 0x44, 0x00,
	0x00, 0x41, 0x7F, 0x40, 0x00,
	0x7C, 0x04, 0x78, 0x04, 0x78,
	0x7C, 0x08, 0x04, 0x04, 0x78,
	0x38, 0x44, 0x44, 0x44, 0x38,
	0xFC, 0x18, 0x24, 0x24, 0x18,
	0x18, 0x24, 0x24, 0x18, 0xFC,
	0x7C, 0x08, 0x04, 0x04, 0x08,
	0x48, 0x54, 0x54, 0x54, 0x24,
	0x04, 0x04, 0x3F, 0x44, 0x24,
	0x3C, 0x40, 0x40, 0x20, 0x7C,
	0x1C, 0x20, 0x40, 0x20, 0x1C,
	0x3C, 0x40, 0x30, 0x40, 0x3C,
	0x44, 0x28, 0x10, 0x28, 0x44,
	0x4C, 0x90, 0x90, 0x90, 0x7C,
	0x44, 0x64, 0x54, 0x4C, 0x44,
	0x00, 0x08, 0x36, 0x41, 0x00,
	0x00, 0x00, 0x77, 0x00, 0x00,
	0x00, 0x41, 0x36, 0x08, 0x00,
	0x02, 0x01, 0x02, 0x04, 0x02,
	0x3C, 0x26, 0x23, 0x26, 0x3C,
	0x1E, 0xA1, 0xA1, 0x61, 0x12,
	0x3A, 0x40, 0x40, 0x20, 0x7A,
	0x38, 0x54, 0x54, 0x55, 0x59,
	0x21, 0x55, 0x55, 0x79, 0x41,
	0x22, 0x54, 0x54, 0x78, 0x42,
	0x21, 0x55, 0x54, 0x78, 0x40,
	0x20, 0x54, 0x55, 0x79, 0x40,
	0x0C, 0x1E, 0x52, 0x72, 0x12,
	0x39, 0x55, 0x55, 0x55, 0x59,
	0x39, 0x54, 0x54, 0x54, 0x59,
	0x39, 0x55, 0x54, 0x54, 0x58,
	0x00, 0x00, 0x45, 0x7C, 0x41,
	0x00, 0x02, 0x45, 0x7D, 0x42,
	0x00, 0x01, 0x45, 0x7C, 0x40,
	0x7D, 0x12, 0x11, 0x12, 0x7D,
	0xF0, 0x28, 0x25, 0x28, 0xF0,
	0x7C, 0x54, 0x55, 0x45, 0x00,
	0x20, 0x54, 0x54, 0x7C, 0x54,
	0x7C, 0x0A, 0x09, 0x7F, 0x49,
	0x32, 0x49, 0x49, 0x49, 0x32,
	0x3A, 0x44, 0x44, 0x44, 0x3A, 
	0x32, 0x4A, 0x48, 0x48, 0x30,
	0x3A, 0x41, 0x41, 0x21, 0x7A,
	0x3A, 0x42, 0x40, 0x20, 0x78,
	0x00, 0x9D, 0xA0, 0xA0, 0x7D,
	0x3D, 0x42, 0x42, 0x42, 0x3D, 
	0x3D, 0x40, 0x40, 0x40, 0x3D,
	0x3C, 0x24, 0xFF, 0x24, 0x24,
	0x48, 0x7E, 0x49, 0x43, 0x66,
	0x2B, 0x2F, 0xFC, 0x2F, 0x2B,
	0xFF, 0x09, 0x29, 0xF6, 0x20,
	0xC0, 0x88, 0x7E, 0x09, 0x03,
	0x20, 0x54, 0x54, 0x79, 0x41,
	0x00, 0x00, 0x44, 0x7D, 0x41,
	0x30, 0x48, 0x48, 0x4A, 0x32,
	0x38, 0x40, 0x40, 0x22, 0x7A,
	0x00, 0x7A, 0x0A, 0x0A, 0x72,
	0x7D, 0x0D, 0x19, 0x31, 0x7D,
	0x26, 0x29, 0x29, 0x2F, 0x28,
	0x26, 0x29, 0x29, 0x29, 0x26,
	0x30, 0x48, 0x4D, 0x40, 0x20,
	0x38, 0x08, 0x08, 0x08, 0x08,
	0x08, 0x08, 0x08, 0x08, 0x38,
	0x2F, 0x10, 0xC8, 0xAC, 0xBA,
	0x2F, 0x10, 0x28, 0x34, 0xFA,
	0x00, 0x00, 0x7B, 0x00, 0x00,
	0x08, 0x14, 0x2A, 0x14, 0x22,
	0x22, 0x14, 0x2A, 0x14, 0x08,
	0x55, 0x00, 0x55, 0x00, 0x55, 
	0xAA, 0x55, 0xAA, 0x55, 0xAA, 
	0xFF, 0x55, 0xFF, 0x55, 0xFF, 
	0x00, 0x00, 0x00, 0xFF, 0x00,
	0x10, 0x10, 0x10, 0xFF, 0x00,
	0x14, 0x14, 0x14, 0xFF, 0x00,
	0x10, 0x10, 0xFF, 0x00, 0xFF,
	0x10, 0x10, 0xF0, 0x10, 0xF0,
	0x14, 0x14, 0x14, 0xFC, 0x00,
	0x14, 0x14, 0xF7, 0x00, 0xFF,
	0x00, 0x00, 0xFF, 0x00, 0xFF,
	0x14, 0x14, 0xF4, 0x04, 0xFC,
	0x14, 0x14, 0x17, 0x10, 0x1F,
	0x10, 0x10, 0x1F, 0x10, 0x1F,
	0x14, 0x14, 0x14, 0x1F, 0x00,
	0x10, 0x10, 0x10, 0xF0, 0x00,
	0x00, 0x00, 0x00, 0x1F, 0x10,
	0x10, 0x10, 0x10, 0x1F, 0x10,
	0x10, 0x10, 0x10, 0xF0, 0x10,
	0x00, 0x00, 0x00, 0xFF, 0x10,
	0x10, 0x10, 0x10, 0x10, 0x10,
	0x10, 0x10, 0x10, 0xFF, 0x10,
	0x00, 0x00, 0x00, 0xFF, 0x14,
	0x00, 0x00, 0xFF, 0x00, 0xFF,
	0x00, 0x00, 0x1F, 0x10, 0x17,
	0x00, 0x00, 0xFC, 0x04, 0xF4,
	0x14, 0x14, 0x17, 0x10, 0x17,
	0x14, 0x14, 0xF4, 0x04, 0xF4,
	0x00, 0x00, 0xFF, 0x00, 0xF7,
	0x14, 0x14, 0x14, 0x14, 0x14,
	0x14, 0x14, 0xF7, 0x00, 0xF7,
	0x14, 0x14, 0x14, 0x17, 0x14,
	0x10, 0x10, 0x1F, 0x10, 0x1F,
	0x14, 0x14, 0x14, 0xF4, 0x14,
	0x10, 0x10, 0xF0, 0x10, 0xF0,
	0x00, 0x00, 0x1F, 0x10, 0x1F,
	0x00, 0x00, 0x00, 0x1F, 0x14,
	0x00, 0x00, 0x00, 0xFC, 0x14,
	0x00, 0x00, 0xF0, 0x10, 0xF0,
	0x10, 0x10, 0xFF, 0x10, 0xFF,
	0x14, 0x14, 0x14, 0xFF, 0x14,
	0x10, 0x10, 0x10, 0x1F, 0x00,
	0x00, 0x00, 0x00, 0xF0, 0x10,
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
	0xF0, 0xF0, 0xF0, 0xF0, 0xF0,
	0xFF, 0xFF, 0xFF, 0x00, 0x00,
	0x00, 0x00, 0x00, 0xFF, 0xFF,
	0x0F, 0x0F, 0x0F, 0x0F, 0x0F,
	0x38, 0x44, 0x44, 0x38, 0x44,
	0xFC, 0x4A, 0x4A, 0x4A, 0x34, 
	0x7E, 0x02, 0x02, 0x06, 0x06,
	0x02, 0x7E, 0x02, 0x7E, 0x02,
	0x63, 0x55, 0x49, 0x41, 0x63,
	0x38, 0x44, 0x44, 0x3C, 0x04,
	0x40, 0x7E, 0x20, 0x1E, 0x20,
	0x06, 0x02, 0x7E, 0x02, 0x02,
	0x99, 0xA5, 0xE7, 0xA5, 0x99,
	0x1C, 0x2A, 0x49, 0x2A, 0x1C,
	0x4C, 0x72, 0x01, 0x72, 0x4C,
	0x30, 0x4A, 0x4D, 0x4D, 0x30,
	0x30, 0x48, 0x78, 0x48, 0x30,
	0xBC, 0x62, 0x5A, 0x46, 0x3D,
	0x3E, 0x49, 0x49, 0x49, 0x00,
	0x7E, 0x01, 0x01, 0x01, 0x7E,
	0x2A, 0x2A, 0x2A, 0x2A, 0x2A,
	0x44, 0x44, 0x5F, 0x44, 0x44,
	0x40, 0x51, 0x4A, 0x44, 0x40,
	0x40, 0x44, 0x4A, 0x51, 0x40,
	0x00, 0x00, 0xFF, 0x01, 0x03,
	0xE0, 0x80, 0xFF, 0x00, 0x00,
	0x08, 0x08, 0x6B, 0x6B, 0x08,
	0x36, 0x12, 0x36, 0x24, 0x36,
	0x06, 0x0F, 0x09, 0x0F, 0x06,
	0x00, 0x00, 0x18, 0x18, 0x00,
	0x00, 0x00, 0x10, 0x10, 0x00,
	0x30, 0x40, 0xFF, 0x01, 0x01,
	0x00, 0x1F, 0x01, 0x01, 0x1E,
	0x00, 0x19, 0x1D, 0x17, 0x12,
	0x00, 0x3C, 0x3C, 0x3C, 0x3C,
	0x00, 0x00, 0x00, 0x00, 0x00  
};

Functions declarations:

//***** Functions prototypes *****//
//1. Write Command to LCD
void ILI9341_SendCommand(uint8_t com);
//2. Write data to LCD
void ILI9341_SendData(uint8_t data);
//2.2 Write multiple/DMA
void ILI9341_SendData_Multi(uint16_t Colordata, uint32_t size);


//3. Set cursor position
void ILI9341_SetCursorPosition(uint16_t x1, uint16_t y1, uint16_t x2, uint16_t y2);
//4. Initialise function
void ILI9341_Init();
//5. Write data to a single pixel
void ILI9341_DrawPixel(uint16_t x, uint16_t y, uint16_t color); //Draw single pixel to ILI9341
//6. Fill the entire screen with a background color
void ILI9341_Fill(uint16_t color); //Fill entire ILI9341 with color
//7. Rectangle drawing functions
void ILI9341_Fill_Rect(unsigned int x0, unsigned int y0, unsigned int x1, unsigned int y1, uint16_t color);
//8. Circle drawing functions
void ILI9341_drawCircle(int16_t x0, int16_t y0, int16_t r, uint16_t color);
static void drawCircleHelper( int16_t x0, int16_t y0, int16_t r, uint8_t cornername, uint16_t color);
static void fillCircleHelper(int16_t x0, int16_t y0, int16_t r, uint8_t cornername, int16_t delta, uint16_t color);
void ILI9341_fillCircle(int16_t x0, int16_t y0, int16_t r, uint16_t color);
//9. Line drawing functions
void ILI9341_drawLine(int16_t x0, int16_t y0, int16_t x1, int16_t y1, uint16_t color);
void ILI9341_drawFastHLine(int16_t x, int16_t y, int16_t w, uint16_t color);
void ILI9341_drawFastVLine(int16_t x, int16_t y, int16_t h, uint16_t color);
//10. Triangle drawing
void ILI9341_drawTriangle(int16_t x0, int16_t y0, int16_t x1, int16_t y1, int16_t x2, int16_t y2, uint16_t color);
void ILI9341_fillTriangle(int16_t x0, int16_t y0, int16_t x1, int16_t y1, int16_t x2, int16_t y2, uint16_t color);
//11. Text printing functions
//void ILI9341_drawChar(int16_t x, int16_t y, unsigned char c, uint16_t color, uint16_t bg, uint8_t size);
//void ILI9341_printText(char text[], int16_t x, int16_t y, uint16_t color, uint16_t bg, uint8_t size);
//12. Image print (RGB 565, 2 bytes per pixel)
void ILI9341_printImage(uint16_t x, uint16_t y, uint16_t w, uint16_t h, uint8_t *data, uint32_t size);
//13. Set screen rotation
void ILI9341_setRotation(uint8_t rotate);
//14. Get screen rotation
uint8_t ILI9341_getRotation(void);
//draw a single character 
void ILI9341_DrawChar(int16_t x, int16_t y, char c, int16_t textColor, int16_t bgColor, uint8_t size);
//sensd 16-bit color data
uint16_t ILI9341_Color565(uint8_t r, uint8_t g, uint8_t b);
//write a string to the lcd 
uint32_t ILI9341_DrawString(uint16_t x, uint16_t y, char *pt, int16_t textColor,int16_t BG,uint16_t size);

Hence, the entire header file as following:

#ifndef ILI9341_H_
#define ILI9341_H_

//List of includes
#include <stdbool.h>
#include "delay.h"
#include <stdint.h>
#include <math.h>


//LCD dimensions defines
#define ILI9341_WIDTH       240
#define ILI9341_HEIGHT      320


#define ILI9341_PIXEL_COUNT	ILI9341_WIDTH * ILI9341_HEIGHT


//ILI9341 LCD commands
#define ILI9341_RESET			 		    0x01
#define ILI9341_SLEEP_OUT		  			0x11
#define ILI9341_GAMMA			    		0x26
#define ILI9341_DISPLAY_OFF					0x28
#define ILI9341_DISPLAY_ON					0x29
#define ILI9341_COLUMN_ADDR					0x2A
#define ILI9341_PAGE_ADDR			  		0x2B
#define ILI9341_GRAM				    	0x2C
#define ILI9341_TEARING_OFF					0x34
#define ILI9341_TEARING_ON					0x35
#define ILI9341_DISPLAY_INVERSION			0xb4
#define ILI9341_MAC			        		0x36
#define ILI9341_PIXEL_FORMAT    			0x3A
#define ILI9341_WDB			    	  		0x51
#define ILI9341_WCD				      		0x53
#define ILI9341_RGB_INTERFACE   			0xB0
#define ILI9341_FRC					    	0xB1
#define ILI9341_BPC					    	0xB5
#define ILI9341_DFC				 	    	0xB6
#define ILI9341_Entry_Mode_Set				0xB7
#define ILI9341_POWER1						0xC0
#define ILI9341_POWER2						0xC1
#define ILI9341_VCOM1						0xC5
#define ILI9341_VCOM2						0xC7
#define ILI9341_POWERA						0xCB
#define ILI9341_POWERB						0xCF
#define ILI9341_PGAMMA						0xE0
#define ILI9341_NGAMMA						0xE1
#define ILI9341_DTCA						0xE8
#define ILI9341_DTCB						0xEA
#define ILI9341_POWER_SEQ					0xED
#define ILI9341_3GAMMA_EN					0xF2
#define ILI9341_INTERFACE					0xF6
#define ILI9341_PRC				   	  		0xF7
#define ILI9341_VERTICAL_SCROLL 			0x33

#define ILI9341_MEMCONTROL         	0x36
#define ILI9341_MADCTL_MY  			0x80
#define ILI9341_MADCTL_MX  			0x40
#define ILI9341_MADCTL_MV  			0x20
#define ILI9341_MADCTL_ML  			0x10
#define ILI9341_MADCTL_RGB 			0x00
#define ILI9341_MADCTL_BGR 			0x08
#define ILI9341_MADCTL_MH  			0x04

//List of colors
#define COLOR_BLACK           0x0000  
#define COLOR_NAVY            0x000F      
#define COLOR_DGREEN          0x03E0     
#define COLOR_DCYAN           0x03EF  
#define COLOR_MAROON          0x7800 
#define COLOR_PURPLE          0x780F
#define COLOR_OLIVE           0x7BE0     
#define COLOR_LGRAY           0xC618      
#define COLOR_DGRAY           0x7BEF    
#define COLOR_BLUE            0x001F    
#define COLOR_BLUE2			  0x051D
#define COLOR_GREEN           0x07E0      
#define COLOR_GREEN2		  0xB723
#define COLOR_GREEN3		  0x8000
#define COLOR_CYAN            0x07FF   
#define COLOR_RED             0xF800    
#define COLOR_MAGENTA         0xF81F    
#define COLOR_YELLOW          0xFFE0   
#define COLOR_WHITE           0xFFFF     
#define COLOR_ORANGE          0xFD20     
#define COLOR_GREENYELLOW     0xAFE5     
#define COLOR_BROWN 		  0XBC40
#define COLOR_BRRED 	 	  0XFC07

//Functions defines Macros
#define swap(a, b) { int16_t t = a; a = b; b = t; }
#define min(a,b) (((a)<(b))?(a):(b))

//font

static //Text simple font array (You can your own font)
const unsigned char Font[] = {
	0x00, 0x00, 0x00, 0x00, 0x00,
	0x3E, 0x5B, 0x4F, 0x5B, 0x3E,
	0x3E, 0x6B, 0x4F, 0x6B, 0x3E,
	0x1C, 0x3E, 0x7C, 0x3E, 0x1C,
	0x18, 0x3C, 0x7E, 0x3C, 0x18,
	0x1C, 0x57, 0x7D, 0x57, 0x1C,
	0x1C, 0x5E, 0x7F, 0x5E, 0x1C,
	0x00, 0x18, 0x3C, 0x18, 0x00,
	0xFF, 0xE7, 0xC3, 0xE7, 0xFF,
	0x00, 0x18, 0x24, 0x18, 0x00,
	0xFF, 0xE7, 0xDB, 0xE7, 0xFF,
	0x30, 0x48, 0x3A, 0x06, 0x0E,
	0x26, 0x29, 0x79, 0x29, 0x26,
	0x40, 0x7F, 0x05, 0x05, 0x07,
	0x40, 0x7F, 0x05, 0x25, 0x3F,
	0x5A, 0x3C, 0xE7, 0x3C, 0x5A,
	0x7F, 0x3E, 0x1C, 0x1C, 0x08,
	0x08, 0x1C, 0x1C, 0x3E, 0x7F,
	0x14, 0x22, 0x7F, 0x22, 0x14,
	0x5F, 0x5F, 0x00, 0x5F, 0x5F,
	0x06, 0x09, 0x7F, 0x01, 0x7F,
	0x00, 0x66, 0x89, 0x95, 0x6A,
	0x60, 0x60, 0x60, 0x60, 0x60,
	0x94, 0xA2, 0xFF, 0xA2, 0x94,
	0x08, 0x04, 0x7E, 0x04, 0x08,
	0x10, 0x20, 0x7E, 0x20, 0x10,
	0x08, 0x08, 0x2A, 0x1C, 0x08,
	0x08, 0x1C, 0x2A, 0x08, 0x08,
	0x1E, 0x10, 0x10, 0x10, 0x10,
	0x0C, 0x1E, 0x0C, 0x1E, 0x0C,
	0x30, 0x38, 0x3E, 0x38, 0x30,
	0x06, 0x0E, 0x3E, 0x0E, 0x06,
	0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x5F, 0x00, 0x00,
	0x00, 0x07, 0x00, 0x07, 0x00,
	0x14, 0x7F, 0x14, 0x7F, 0x14,
	0x24, 0x2A, 0x7F, 0x2A, 0x12,
	0x23, 0x13, 0x08, 0x64, 0x62,
	0x36, 0x49, 0x56, 0x20, 0x50,
	0x00, 0x08, 0x07, 0x03, 0x00,
	0x00, 0x1C, 0x22, 0x41, 0x00,
	0x00, 0x41, 0x22, 0x1C, 0x00,
	0x2A, 0x1C, 0x7F, 0x1C, 0x2A,
	0x08, 0x08, 0x3E, 0x08, 0x08,
	0x00, 0x80, 0x70, 0x30, 0x00,
	0x08, 0x08, 0x08, 0x08, 0x08,
	0x00, 0x00, 0x60, 0x60, 0x00,
	0x20, 0x10, 0x08, 0x04, 0x02,
	0x3E, 0x51, 0x49, 0x45, 0x3E,
	0x00, 0x42, 0x7F, 0x40, 0x00,
	0x72, 0x49, 0x49, 0x49, 0x46,
	0x21, 0x41, 0x49, 0x4D, 0x33,
	0x18, 0x14, 0x12, 0x7F, 0x10,
	0x27, 0x45, 0x45, 0x45, 0x39,
	0x3C, 0x4A, 0x49, 0x49, 0x31,
	0x41, 0x21, 0x11, 0x09, 0x07,
	0x36, 0x49, 0x49, 0x49, 0x36,
	0x46, 0x49, 0x49, 0x29, 0x1E,
	0x00, 0x00, 0x14, 0x00, 0x00,
	0x00, 0x40, 0x34, 0x00, 0x00,
	0x00, 0x08, 0x14, 0x22, 0x41,
	0x14, 0x14, 0x14, 0x14, 0x14,
	0x00, 0x41, 0x22, 0x14, 0x08,
	0x02, 0x01, 0x59, 0x09, 0x06,
	0x3E, 0x41, 0x5D, 0x59, 0x4E,
	0x7C, 0x12, 0x11, 0x12, 0x7C,
	0x7F, 0x49, 0x49, 0x49, 0x36,
	0x3E, 0x41, 0x41, 0x41, 0x22,
	0x7F, 0x41, 0x41, 0x41, 0x3E,
	0x7F, 0x49, 0x49, 0x49, 0x41,
	0x7F, 0x09, 0x09, 0x09, 0x01,
	0x3E, 0x41, 0x41, 0x51, 0x73,
	0x7F, 0x08, 0x08, 0x08, 0x7F,
	0x00, 0x41, 0x7F, 0x41, 0x00,
	0x20, 0x40, 0x41, 0x3F, 0x01,
	0x7F, 0x08, 0x14, 0x22, 0x41,
	0x7F, 0x40, 0x40, 0x40, 0x40,
	0x7F, 0x02, 0x1C, 0x02, 0x7F,
	0x7F, 0x04, 0x08, 0x10, 0x7F,
	0x3E, 0x41, 0x41, 0x41, 0x3E,
	0x7F, 0x09, 0x09, 0x09, 0x06,
	0x3E, 0x41, 0x51, 0x21, 0x5E,
	0x7F, 0x09, 0x19, 0x29, 0x46,
	0x26, 0x49, 0x49, 0x49, 0x32,
	0x03, 0x01, 0x7F, 0x01, 0x03,
	0x3F, 0x40, 0x40, 0x40, 0x3F,
	0x1F, 0x20, 0x40, 0x20, 0x1F,
	0x3F, 0x40, 0x38, 0x40, 0x3F,
	0x63, 0x14, 0x08, 0x14, 0x63,
	0x03, 0x04, 0x78, 0x04, 0x03,
	0x61, 0x59, 0x49, 0x4D, 0x43,
	0x00, 0x7F, 0x41, 0x41, 0x41,
	0x02, 0x04, 0x08, 0x10, 0x20,
	0x00, 0x41, 0x41, 0x41, 0x7F,
	0x04, 0x02, 0x01, 0x02, 0x04,
	0x40, 0x40, 0x40, 0x40, 0x40,
	0x00, 0x03, 0x07, 0x08, 0x00,
	0x20, 0x54, 0x54, 0x78, 0x40,
	0x7F, 0x28, 0x44, 0x44, 0x38,
	0x38, 0x44, 0x44, 0x44, 0x28,
	0x38, 0x44, 0x44, 0x28, 0x7F,
	0x38, 0x54, 0x54, 0x54, 0x18,
	0x00, 0x08, 0x7E, 0x09, 0x02,
	0x18, 0xA4, 0xA4, 0x9C, 0x78,
	0x7F, 0x08, 0x04, 0x04, 0x78,
	0x00, 0x44, 0x7D, 0x40, 0x00,
	0x20, 0x40, 0x40, 0x3D, 0x00,
	0x7F, 0x10, 0x28, 0x44, 0x00,
	0x00, 0x41, 0x7F, 0x40, 0x00,
	0x7C, 0x04, 0x78, 0x04, 0x78,
	0x7C, 0x08, 0x04, 0x04, 0x78,
	0x38, 0x44, 0x44, 0x44, 0x38,
	0xFC, 0x18, 0x24, 0x24, 0x18,
	0x18, 0x24, 0x24, 0x18, 0xFC,
	0x7C, 0x08, 0x04, 0x04, 0x08,
	0x48, 0x54, 0x54, 0x54, 0x24,
	0x04, 0x04, 0x3F, 0x44, 0x24,
	0x3C, 0x40, 0x40, 0x20, 0x7C,
	0x1C, 0x20, 0x40, 0x20, 0x1C,
	0x3C, 0x40, 0x30, 0x40, 0x3C,
	0x44, 0x28, 0x10, 0x28, 0x44,
	0x4C, 0x90, 0x90, 0x90, 0x7C,
	0x44, 0x64, 0x54, 0x4C, 0x44,
	0x00, 0x08, 0x36, 0x41, 0x00,
	0x00, 0x00, 0x77, 0x00, 0x00,
	0x00, 0x41, 0x36, 0x08, 0x00,
	0x02, 0x01, 0x02, 0x04, 0x02,
	0x3C, 0x26, 0x23, 0x26, 0x3C,
	0x1E, 0xA1, 0xA1, 0x61, 0x12,
	0x3A, 0x40, 0x40, 0x20, 0x7A,
	0x38, 0x54, 0x54, 0x55, 0x59,
	0x21, 0x55, 0x55, 0x79, 0x41,
	0x22, 0x54, 0x54, 0x78, 0x42,
	0x21, 0x55, 0x54, 0x78, 0x40,
	0x20, 0x54, 0x55, 0x79, 0x40,
	0x0C, 0x1E, 0x52, 0x72, 0x12,
	0x39, 0x55, 0x55, 0x55, 0x59,
	0x39, 0x54, 0x54, 0x54, 0x59,
	0x39, 0x55, 0x54, 0x54, 0x58,
	0x00, 0x00, 0x45, 0x7C, 0x41,
	0x00, 0x02, 0x45, 0x7D, 0x42,
	0x00, 0x01, 0x45, 0x7C, 0x40,
	0x7D, 0x12, 0x11, 0x12, 0x7D,
	0xF0, 0x28, 0x25, 0x28, 0xF0,
	0x7C, 0x54, 0x55, 0x45, 0x00,
	0x20, 0x54, 0x54, 0x7C, 0x54,
	0x7C, 0x0A, 0x09, 0x7F, 0x49,
	0x32, 0x49, 0x49, 0x49, 0x32,
	0x3A, 0x44, 0x44, 0x44, 0x3A, 
	0x32, 0x4A, 0x48, 0x48, 0x30,
	0x3A, 0x41, 0x41, 0x21, 0x7A,
	0x3A, 0x42, 0x40, 0x20, 0x78,
	0x00, 0x9D, 0xA0, 0xA0, 0x7D,
	0x3D, 0x42, 0x42, 0x42, 0x3D, 
	0x3D, 0x40, 0x40, 0x40, 0x3D,
	0x3C, 0x24, 0xFF, 0x24, 0x24,
	0x48, 0x7E, 0x49, 0x43, 0x66,
	0x2B, 0x2F, 0xFC, 0x2F, 0x2B,
	0xFF, 0x09, 0x29, 0xF6, 0x20,
	0xC0, 0x88, 0x7E, 0x09, 0x03,
	0x20, 0x54, 0x54, 0x79, 0x41,
	0x00, 0x00, 0x44, 0x7D, 0x41,
	0x30, 0x48, 0x48, 0x4A, 0x32,
	0x38, 0x40, 0x40, 0x22, 0x7A,
	0x00, 0x7A, 0x0A, 0x0A, 0x72,
	0x7D, 0x0D, 0x19, 0x31, 0x7D,
	0x26, 0x29, 0x29, 0x2F, 0x28,
	0x26, 0x29, 0x29, 0x29, 0x26,
	0x30, 0x48, 0x4D, 0x40, 0x20,
	0x38, 0x08, 0x08, 0x08, 0x08,
	0x08, 0x08, 0x08, 0x08, 0x38,
	0x2F, 0x10, 0xC8, 0xAC, 0xBA,
	0x2F, 0x10, 0x28, 0x34, 0xFA,
	0x00, 0x00, 0x7B, 0x00, 0x00,
	0x08, 0x14, 0x2A, 0x14, 0x22,
	0x22, 0x14, 0x2A, 0x14, 0x08,
	0x55, 0x00, 0x55, 0x00, 0x55, 
	0xAA, 0x55, 0xAA, 0x55, 0xAA, 
	0xFF, 0x55, 0xFF, 0x55, 0xFF, 
	0x00, 0x00, 0x00, 0xFF, 0x00,
	0x10, 0x10, 0x10, 0xFF, 0x00,
	0x14, 0x14, 0x14, 0xFF, 0x00,
	0x10, 0x10, 0xFF, 0x00, 0xFF,
	0x10, 0x10, 0xF0, 0x10, 0xF0,
	0x14, 0x14, 0x14, 0xFC, 0x00,
	0x14, 0x14, 0xF7, 0x00, 0xFF,
	0x00, 0x00, 0xFF, 0x00, 0xFF,
	0x14, 0x14, 0xF4, 0x04, 0xFC,
	0x14, 0x14, 0x17, 0x10, 0x1F,
	0x10, 0x10, 0x1F, 0x10, 0x1F,
	0x14, 0x14, 0x14, 0x1F, 0x00,
	0x10, 0x10, 0x10, 0xF0, 0x00,
	0x00, 0x00, 0x00, 0x1F, 0x10,
	0x10, 0x10, 0x10, 0x1F, 0x10,
	0x10, 0x10, 0x10, 0xF0, 0x10,
	0x00, 0x00, 0x00, 0xFF, 0x10,
	0x10, 0x10, 0x10, 0x10, 0x10,
	0x10, 0x10, 0x10, 0xFF, 0x10,
	0x00, 0x00, 0x00, 0xFF, 0x14,
	0x00, 0x00, 0xFF, 0x00, 0xFF,
	0x00, 0x00, 0x1F, 0x10, 0x17,
	0x00, 0x00, 0xFC, 0x04, 0xF4,
	0x14, 0x14, 0x17, 0x10, 0x17,
	0x14, 0x14, 0xF4, 0x04, 0xF4,
	0x00, 0x00, 0xFF, 0x00, 0xF7,
	0x14, 0x14, 0x14, 0x14, 0x14,
	0x14, 0x14, 0xF7, 0x00, 0xF7,
	0x14, 0x14, 0x14, 0x17, 0x14,
	0x10, 0x10, 0x1F, 0x10, 0x1F,
	0x14, 0x14, 0x14, 0xF4, 0x14,
	0x10, 0x10, 0xF0, 0x10, 0xF0,
	0x00, 0x00, 0x1F, 0x10, 0x1F,
	0x00, 0x00, 0x00, 0x1F, 0x14,
	0x00, 0x00, 0x00, 0xFC, 0x14,
	0x00, 0x00, 0xF0, 0x10, 0xF0,
	0x10, 0x10, 0xFF, 0x10, 0xFF,
	0x14, 0x14, 0x14, 0xFF, 0x14,
	0x10, 0x10, 0x10, 0x1F, 0x00,
	0x00, 0x00, 0x00, 0xF0, 0x10,
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
	0xF0, 0xF0, 0xF0, 0xF0, 0xF0,
	0xFF, 0xFF, 0xFF, 0x00, 0x00,
	0x00, 0x00, 0x00, 0xFF, 0xFF,
	0x0F, 0x0F, 0x0F, 0x0F, 0x0F,
	0x38, 0x44, 0x44, 0x38, 0x44,
	0xFC, 0x4A, 0x4A, 0x4A, 0x34, 
	0x7E, 0x02, 0x02, 0x06, 0x06,
	0x02, 0x7E, 0x02, 0x7E, 0x02,
	0x63, 0x55, 0x49, 0x41, 0x63,
	0x38, 0x44, 0x44, 0x3C, 0x04,
	0x40, 0x7E, 0x20, 0x1E, 0x20,
	0x06, 0x02, 0x7E, 0x02, 0x02,
	0x99, 0xA5, 0xE7, 0xA5, 0x99,
	0x1C, 0x2A, 0x49, 0x2A, 0x1C,
	0x4C, 0x72, 0x01, 0x72, 0x4C,
	0x30, 0x4A, 0x4D, 0x4D, 0x30,
	0x30, 0x48, 0x78, 0x48, 0x30,
	0xBC, 0x62, 0x5A, 0x46, 0x3D,
	0x3E, 0x49, 0x49, 0x49, 0x00,
	0x7E, 0x01, 0x01, 0x01, 0x7E,
	0x2A, 0x2A, 0x2A, 0x2A, 0x2A,
	0x44, 0x44, 0x5F, 0x44, 0x44,
	0x40, 0x51, 0x4A, 0x44, 0x40,
	0x40, 0x44, 0x4A, 0x51, 0x40,
	0x00, 0x00, 0xFF, 0x01, 0x03,
	0xE0, 0x80, 0xFF, 0x00, 0x00,
	0x08, 0x08, 0x6B, 0x6B, 0x08,
	0x36, 0x12, 0x36, 0x24, 0x36,
	0x06, 0x0F, 0x09, 0x0F, 0x06,
	0x00, 0x00, 0x18, 0x18, 0x00,
	0x00, 0x00, 0x10, 0x10, 0x00,
	0x30, 0x40, 0xFF, 0x01, 0x01,
	0x00, 0x1F, 0x01, 0x01, 0x1E,
	0x00, 0x19, 0x1D, 0x17, 0x12,
	0x00, 0x3C, 0x3C, 0x3C, 0x3C,
	0x00, 0x00, 0x00, 0x00, 0x00  
};



//***** Functions prototypes *****//
//1. Write Command to LCD
void ILI9341_SendCommand(uint8_t com);
//2. Write data to LCD
void ILI9341_SendData(uint8_t data);
//2.2 Write multiple/DMA
void ILI9341_SendData_Multi(uint16_t Colordata, uint32_t size);


//3. Set cursor position
void ILI9341_SetCursorPosition(uint16_t x1, uint16_t y1, uint16_t x2, uint16_t y2);
//4. Initialise function
void ILI9341_Init();
//5. Write data to a single pixel
void ILI9341_DrawPixel(uint16_t x, uint16_t y, uint16_t color); //Draw single pixel to ILI9341
//6. Fill the entire screen with a background color
void ILI9341_Fill(uint16_t color); //Fill entire ILI9341 with color
//7. Rectangle drawing functions
void ILI9341_Fill_Rect(unsigned int x0, unsigned int y0, unsigned int x1, unsigned int y1, uint16_t color);
//8. Circle drawing functions
void ILI9341_drawCircle(int16_t x0, int16_t y0, int16_t r, uint16_t color);
static void drawCircleHelper( int16_t x0, int16_t y0, int16_t r, uint8_t cornername, uint16_t color);
static void fillCircleHelper(int16_t x0, int16_t y0, int16_t r, uint8_t cornername, int16_t delta, uint16_t color);
void ILI9341_fillCircle(int16_t x0, int16_t y0, int16_t r, uint16_t color);
//9. Line drawing functions
void ILI9341_drawLine(int16_t x0, int16_t y0, int16_t x1, int16_t y1, uint16_t color);
void ILI9341_drawFastHLine(int16_t x, int16_t y, int16_t w, uint16_t color);
void ILI9341_drawFastVLine(int16_t x, int16_t y, int16_t h, uint16_t color);
//10. Triangle drawing
void ILI9341_drawTriangle(int16_t x0, int16_t y0, int16_t x1, int16_t y1, int16_t x2, int16_t y2, uint16_t color);
void ILI9341_fillTriangle(int16_t x0, int16_t y0, int16_t x1, int16_t y1, int16_t x2, int16_t y2, uint16_t color);
//11. Text printing functions
//void ILI9341_drawChar(int16_t x, int16_t y, unsigned char c, uint16_t color, uint16_t bg, uint8_t size);
//void ILI9341_printText(char text[], int16_t x, int16_t y, uint16_t color, uint16_t bg, uint8_t size);
//12. Image print (RGB 565, 2 bytes per pixel)
void ILI9341_printImage(uint16_t x, uint16_t y, uint16_t w, uint16_t h, uint8_t *data, uint32_t size);
//13. Set screen rotation
void ILI9341_setRotation(uint8_t rotate);
//14. Get screen rotation
uint8_t ILI9341_getRotation(void);
//draw a single character 
void ILI9341_DrawChar(int16_t x, int16_t y, char c, int16_t textColor, int16_t bgColor, uint8_t size);
//sensd 16-bit color data
uint16_t ILI9341_Color565(uint8_t r, uint8_t g, uint8_t b);
//write a string to the lcd 
uint32_t ILI9341_DrawString(uint16_t x, uint16_t y, char *pt, int16_t textColor,int16_t BG,uint16_t size);

#endif

Now, create new source file with name of ILI9341.c.

Within the source file, include the following:

//most of the functions has been documented in the interface file (ILI9341.h)
#include "ILI9341.h"
#include "LCD_Pins.h"

Variables needed for calculations:

static uint8_t rotationNum=1;
static uint8_t ColStart, RowStart;

For the initialization function:

//initialize the tft
void ILI9341_Init(void)
{


	LCD_Write_Cmd (ILI9341_DISPLAY_OFF); // display off
	//------------power control------------------------------
	LCD_Write_Cmd (ILI9341_POWER1); // power control
	LCD_Write_Data   (0x26); // GVDD = 4.75v
	LCD_Write_Cmd (ILI9341_POWER2); // power control
	LCD_Write_Data   (0x11); // AVDD=VCIx2, VGH=VCIx7, VGL=-VCIx3
	//--------------VCOM-------------------------------------
	LCD_Write_Cmd (ILI9341_VCOM1); // vcom control
	LCD_Write_Data   (0x35); // Set the VCOMH voltage (0x35 = 4.025v)
	LCD_Write_Data   (0x3e); // Set the VCOML voltage (0x3E = -0.950v)
	LCD_Write_Cmd (ILI9341_VCOM2); // vcom control
	LCD_Write_Data   (0xbe);

	//------------memory access control------------------------
	LCD_Write_Cmd (ILI9341_MAC); // memory access control
	LCD_Write_Data(0x48);

	LCD_Write_Cmd (ILI9341_PIXEL_FORMAT); // pixel format set
	LCD_Write_Data   (0x55); // 16bit /pixel

	LCD_Write_Cmd(ILI9341_FRC);
	LCD_Write_Data(0);
	LCD_Write_Data(0x1F);
	//-------------ddram ----------------------------
	LCD_Write_Cmd (ILI9341_COLUMN_ADDR); // column set
	LCD_Write_Data   (0x00); // x0_HIGH---0
	LCD_Write_Data   (0x00); // x0_LOW----0
	LCD_Write_Data   (0x00); // x1_HIGH---240
	LCD_Write_Data   (0x1D); // x1_LOW----240
	LCD_Write_Cmd (ILI9341_PAGE_ADDR); // page address set
	LCD_Write_Data   (0x00); // y0_HIGH---0
	LCD_Write_Data   (0x00); // y0_LOW----0
	LCD_Write_Data   (0x00); // y1_HIGH---320
	LCD_Write_Data   (0x27); // y1_LOW----320

	LCD_Write_Cmd (ILI9341_TEARING_OFF); // tearing effect off
	//LCD_write_cmd(ILI9341_TEARING_ON); // tearing effect on
	//LCD_write_cmd(ILI9341_DISPLAY_INVERSION); // display inversion
	LCD_Write_Cmd (ILI9341_Entry_Mode_Set); // entry mode set
	// Deep Standby Mode: OFF
	// Set the output level of gate driver G1-G320: Normal display
	// Low voltage detection: Disable
	LCD_Write_Data   (0x07);
	//-----------------display------------------------
	LCD_Write_Cmd (ILI9341_DFC); // display function control
	//Set the scan mode in non-display area
	//Determine source/VCOM output in a non-display area in the partial display mode
	LCD_Write_Data   (0x0a);
	//Select whether the liquid crystal type is normally white type or normally black type
	//Sets the direction of scan by the gate driver in the range determined by SCN and NL
	//Select the shift direction of outputs from the source driver
	//Sets the gate driver pin arrangement in combination with the GS bit to select the optimal scan mode for the module
	//Specify the scan cycle interval of gate driver in non-display area when PTG to select interval scan
	LCD_Write_Data   (0x82);
	// Sets the number of lines to drive the LCD at an interval of 8 lines
	LCD_Write_Data   (0x27);
	LCD_Write_Data   (0x00); // clock divisor

	LCD_Write_Cmd (ILI9341_SLEEP_OUT); // sleep out
	delay(100);
	LCD_Write_Cmd (ILI9341_DISPLAY_ON); // display on
	delay(100);
	LCD_Write_Cmd (ILI9341_GRAM); // memory write
	delay(5);

}

3. Supporting functions:

//set the address of the pixel in the memory 
void static setAddrWindow(uint8_t x0, uint8_t y0, uint8_t x1, uint8_t y1)
{

	LCD_Write_Cmd(0x2A); // Column addr set
	LCD_Write_Data(0x00);
	LCD_Write_Data(x0+ColStart);     // XSTART
	LCD_Write_Data(0x00);
	LCD_Write_Data(x1+ColStart);     // XEND

	LCD_Write_Cmd(0x2B); // Row addr set
	LCD_Write_Data(0x00);
	LCD_Write_Data(y0+RowStart);     // YSTART
	LCD_Write_Data(0x00);
	LCD_Write_Data(y1+RowStart);     // YEND

	LCD_Write_Cmd(0x2C); // write to RAM
}

//internally needed function to push 16-bit color as 2 8-bit data
void static pushColor(uint16_t color)
{
	LCD_Write_Data((uint8_t)(color >> 8));
	LCD_Write_Data((uint8_t)color);
}

//set cursor function
void ILI9341_SetCursorPosition(uint16_t x1, uint16_t y1, uint16_t x2, uint16_t y2)
{
	LCD_Write_Cmd (ILI9341_COLUMN_ADDR);
	LCD_Write_Data(x1>>8);
	LCD_Write_Data(x1 & 0xFF);
	LCD_Write_Data(x2>>8);
	LCD_Write_Data(x2 & 0xFF);
	LCD_Write_Cmd (ILI9341_PAGE_ADDR);
	LCD_Write_Data(y1>>8);
	LCD_Write_Data(y1 & 0xFF);
	LCD_Write_Data(y2>>8);
	LCD_Write_Data(y2 & 0xFF);
	LCD_Write_Cmd (ILI9341_GRAM);
}

void ILI9341_DrawPixel(uint16_t x, uint16_t y, uint16_t color)
{
	ILI9341_SetCursorPosition(x, y, x, y);
	LCD_Write_Data(color>>8);
	LCD_Write_Data(color&0xFF);
}

void ILI9341_Fill(uint16_t color)
{
	uint32_t n = ILI9341_PIXEL_COUNT;
	uint16_t myColor = 0xFF;
	
	if(rotationNum==1 || rotationNum==3)
	{
		ILI9341_SetCursorPosition(0, 0,   ILI9341_WIDTH -1, ILI9341_HEIGHT -1);
	}
	else if(rotationNum==2 || rotationNum==4)
	{
		ILI9341_SetCursorPosition(0, 0, ILI9341_HEIGHT -1, ILI9341_WIDTH -1);
	}
	
	
	while (n)
	{
		n--;
		LCD_Write_Data(color>>8);
		LCD_Write_Data(color&0xff);
	}
}



void ILI9341_Fill_Rect(unsigned int x0,unsigned int y0, unsigned int x1,unsigned int y1, uint16_t color) { 
	uint32_t n = ((x1+1)-x0)*((y1+1)-y0);
	if (n>ILI9341_PIXEL_COUNT) n=ILI9341_PIXEL_COUNT;
	ILI9341_SetCursorPosition(x0, y0, x1, y1);
	while (n)
	{
		n--;
		LCD_Write_Data(color>>8);
		LCD_Write_Data(color&0xff);
	}
}

void ILI9341_drawCircle(int16_t x0, int16_t y0, int16_t r, uint16_t color)
{
	int16_t f = 1 - r;
	int16_t ddF_x = 1;
	int16_t ddF_y = -2 * r;
	int16_t x = 0;
	int16_t y = r;

	ILI9341_DrawPixel(x0  , y0+r, color);
	ILI9341_DrawPixel(x0  , y0-r, color);
	ILI9341_DrawPixel(x0+r, y0  , color);
	ILI9341_DrawPixel(x0-r, y0  , color);

	while (x<y)
	{
		if (f >= 0)
		{
			y--;
			ddF_y += 2;
			f += ddF_y;
		}
		x++;
		ddF_x += 2;
		f += ddF_x;

		ILI9341_DrawPixel(x0 + x, y0 + y, color);
		ILI9341_DrawPixel(x0 - x, y0 + y, color);
		ILI9341_DrawPixel(x0 + x, y0 - y, color);
		ILI9341_DrawPixel(x0 - x, y0 - y, color);
		ILI9341_DrawPixel(x0 + y, y0 + x, color);
		ILI9341_DrawPixel(x0 - y, y0 + x, color);
		ILI9341_DrawPixel(x0 + y, y0 - x, color);
		ILI9341_DrawPixel(x0 - y, y0 - x, color);
	}
}
static void drawCircleHelper( int16_t x0, int16_t y0, int16_t r, uint8_t cornername, uint16_t color)
{
	int16_t f     = 1 - r;
	int16_t ddF_x = 1;
	int16_t ddF_y = -2 * r;
	int16_t x     = 0;
	int16_t y     = r;

	while (x<y)
	{
		if (f >= 0)
		{
			y--;
			ddF_y += 2;
			f += ddF_y;
		}
		x++;
		ddF_x += 2;
		f+= ddF_x;
		if (cornername & 0x4)
		{
			ILI9341_DrawPixel(x0 + x, y0 + y, color);
			ILI9341_DrawPixel(x0 + y, y0 + x, color);
		}
		if (cornername & 0x2) {
				ILI9341_DrawPixel(x0 + x, y0 - y, color);
				ILI9341_DrawPixel(x0 + y, y0 - x, color);
		}
		if (cornername & 0x8) {
			ILI9341_DrawPixel(x0 - y, y0 + x, color);
			ILI9341_DrawPixel(x0 - x, y0 + y, color);
		}
		if (cornername & 0x1)
		{
			ILI9341_DrawPixel(x0 - y, y0 - x, color);
			ILI9341_DrawPixel(x0 - x, y0 - y, color);
		}
	}
}
static void fillCircleHelper(int16_t x0, int16_t y0, int16_t r, uint8_t cornername, int16_t delta, uint16_t color)
{
	int16_t f     = 1 - r;
	int16_t ddF_x = 1;
	int16_t ddF_y = -2 * r;
	int16_t x     = 0;
	int16_t y     = r;

	while (x<y)
	{
		if (f >= 0)
		{
			y--;
			ddF_y += 2;
			f+= ddF_y;
		}
		x++;
		ddF_x += 2;
		f += ddF_x;

		if (cornername & 0x1)
		{
			ILI9341_drawFastVLine(x0+x, y0-y, 2*y+1+delta, color);
			ILI9341_drawFastVLine(x0+y, y0-x, 2*x+1+delta, color);
		}
		if (cornername & 0x2)
		{
			ILI9341_drawFastVLine(x0-x, y0-y, 2*y+1+delta, color);
			ILI9341_drawFastVLine(x0-y, y0-x, 2*x+1+delta, color);
		}
	}
}
void ILI9341_fillCircle(int16_t x0, int16_t y0, int16_t r, uint16_t color)
{
	ILI9341_drawFastVLine(x0, y0-r, 2*r+1, color);
	fillCircleHelper(x0, y0, r, 3, 0, color);
}
void ILI9341_drawLine(int16_t x0, int16_t y0, int16_t x1, int16_t y1, uint16_t color)
{
	int16_t steep = abs(y1 - y0) > abs(x1 - x0);
	if (steep)
	{
		swap(x0, y0);
		swap(x1, y1);
	}

	if (x0 > x1)
	{
		swap(x0, x1);
		swap(y0, y1);
	}

	int16_t dx, dy;
	dx = x1 - x0;
	dy = abs(y1 - y0);

	int16_t err = dx / 2;
	int16_t ystep;

	if (y0 < y1)
	{
		ystep = 1;
	}
	else
	{
		ystep = -1;
	}

	for (; x0<=x1; x0++)
	{
		if (steep)
		{
			ILI9341_DrawPixel(y0, x0, color);
		}
		else
		{
			ILI9341_DrawPixel(x0, y0, color);
		}
		err -= dy;
		if (err < 0)
		{
			y0 += ystep;
			err += dx;
		}
	}
}	

void ILI9341_drawFastHLine(int16_t x, int16_t y, int16_t w, uint16_t color)
{
	ILI9341_drawLine(x, y, x+w-1, y, color);
}

void ILI9341_drawFastVLine(int16_t x, int16_t y, int16_t h, uint16_t color)
{
	ILI9341_drawLine(x, y, x, y+h-1, color);
}
//10. Triangle drawing
void ILI9341_drawTriangle(int16_t x0, int16_t y0, int16_t x1, int16_t y1, int16_t x2, int16_t y2, uint16_t color)
{
	ILI9341_drawLine(x0, y0, x1, y1, color);
	ILI9341_drawLine(x1, y1, x2, y2, color);
	ILI9341_drawLine(x2, y2, x0, y0, color);
}
void ILI9341_fillTriangle(int16_t x0, int16_t y0, int16_t x1, int16_t y1, int16_t x2, int16_t y2, uint16_t color)
{
	int16_t a, b, y, last;

	// Sort coordinates by Y order (y2 >= y1 >= y0)
	if (y0 > y1) {
	swap(y0, y1); swap(x0, x1);
	}
	if (y1 > y2) {
	swap(y2, y1); swap(x2, x1);
	}
	if (y0 > y1) {
	swap(y0, y1); swap(x0, x1);
	}

	if(y0 == y2) { // Handle awkward all-on-same-line case as its own thing
	a = b = x0;
	if(x1 < a)      a = x1;
	else if(x1 > b) b = x1;
	if(x2 < a)      a = x2;
	else if(x2 > b) b = x2;
	ILI9341_drawFastHLine(a, y0, b-a+1, color);
	return;
	}

	int16_t
	dx01 = x1 - x0,
	dy01 = y1 - y0,
	dx02 = x2 - x0,
	dy02 = y2 - y0,
	dx12 = x2 - x1,
	dy12 = y2 - y1,
	sa   = 0,
	sb   = 0;

	// For upper part of triangle, find scanline crossings for segments
	// 0-1 and 0-2.  If y1=y2 (flat-bottomed triangle), the scanline y1
	// is included here (and second loop will be skipped, avoiding a /0
	// error there), otherwise scanline y1 is skipped here and handled
	// in the second loop...which also avoids a /0 error here if y0=y1
	// (flat-topped triangle).
	if(y1 == y2) last = y1;   // Include y1 scanline
	else         last = y1-1; // Skip it

	for(y=y0; y<=last; y++) {
	a   = x0 + sa / dy01;
	b   = x0 + sb / dy02;
	sa += dx01;
	sb += dx02;

	if(a > b) swap(a,b);
	ILI9341_drawFastHLine(a, y, b-a+1, color);
	}

	// For lower part of triangle, find scanline crossings for segments
	// 0-2 and 1-2.  This loop is skipped if y1=y2.
	sa = dx12 * (y - y1);
	sb = dx02 * (y - y0);
	for(; y<=y2; y++) {
	a   = x1 + sa / dy12;
	b   = x0 + sb / dy02;
	sa += dx12;
	sb += dx02;

	if(a > b) swap(a,b);
	ILI9341_drawFastHLine(a, y, b-a+1, color);
	}
}

void ILI9341_setRotation(uint8_t rotate)
{
	switch(rotate)
	{
	case 1:
	rotationNum = 1;
	LCD_Write_Cmd(ILI9341_MEMCONTROL);
	LCD_Write_Data(ILI9341_MADCTL_MY | ILI9341_MADCTL_BGR);
	break;
	case 2:
	rotationNum = 2;
	LCD_Write_Cmd(ILI9341_MEMCONTROL);
	LCD_Write_Data(ILI9341_MADCTL_MV | ILI9341_MADCTL_BGR);
	break;
	case 3:
	rotationNum = 3;
	LCD_Write_Cmd(ILI9341_MEMCONTROL);
	LCD_Write_Data(ILI9341_MADCTL_MX | ILI9341_MADCTL_BGR);
	break;
	case 4:
	rotationNum = 4;
	LCD_Write_Cmd(ILI9341_MEMCONTROL);
	LCD_Write_Data(ILI9341_MADCTL_MX | ILI9341_MADCTL_MY | ILI9341_MADCTL_MV | ILI9341_MADCTL_BGR);
	break;
	default:
	rotationNum = 1;
	LCD_Write_Cmd(ILI9341_MEMCONTROL);
	LCD_Write_Data(ILI9341_MADCTL_MY | ILI9341_MADCTL_BGR);
	break;
	}
}

void ILI9341_DrawChar(int16_t x, int16_t y, char c, int16_t textColor, int16_t bgColor, uint8_t size){
	uint8_t line; // horizontal row of pixels of character
	int32_t col, row, i, j;// loop indices
	if(((x + 5*size - 1) >= ILI9341_WIDTH)  || // Clip right
	((y + 8*size - 1) >= ILI9341_HEIGHT) || // Clip bottom
	((x + 5*size - 1) < 0)        || // Clip left
	((y + 8*size - 1) < 0)){         // Clip top
	return;
	}

	setAddrWindow(x, y, x+6*size-1, y+8*size-1);

	line = 0x01;        // print the top row first
	// print the rows, starting at the top
	for(row=0; row<8; row=row+1){
	for(i=0; i<size; i=i+1){
	// print the columns, starting on the left
	for(col=0; col<5; col=col+1){
	if(Font[(c*5)+col]&line){
	// bit is set in Font, print pixel(s) in text color
	for(j=0; j<size; j=j+1){
	pushColor(textColor);
	}
	} else{
	// bit is cleared in Font, print pixel(s) in background color
	for(j=0; j<size; j=j+1){
	pushColor(bgColor);
	}
	}
	}
	// print blank column(s) to the right of character
	for(j=0; j<size; j=j+1){
	pushColor(bgColor);
	}
	}
	line = line<<1;   // move up to the next row
	}
}
uint16_t ILI9341_Color565(uint8_t r, uint8_t g, uint8_t b) {
	return ((b & 0xF8) << 8) | ((g & 0xFC) << 3) | (r >> 3);
}

uint32_t ILI9341_DrawString(uint16_t x, uint16_t y, char *pt, int16_t textColor, int16_t BG,uint16_t size){
	uint32_t count = 0;

	while(*pt!='\0')
	{

		ILI9341_DrawChar(x*6*size, y*10*size, *pt, textColor, BG, size);
		pt++;
		x = x+1;
		count++;
	}
	return count;  // number of characters printed
}

Hence, the entire source code as following:

//most of the functions has been documented in the interface file (ILI9341.h)
#include "ILI9341.h"
#include "LCD_Pins.h"


static uint8_t rotationNum=1;
static uint8_t ColStart, RowStart;


//initialize the tft
void ILI9341_Init(void)
{


	LCD_Write_Cmd (ILI9341_DISPLAY_OFF); // display off
	//------------power control------------------------------
	LCD_Write_Cmd (ILI9341_POWER1); // power control
	LCD_Write_Data   (0x26); // GVDD = 4.75v
	LCD_Write_Cmd (ILI9341_POWER2); // power control
	LCD_Write_Data   (0x11); // AVDD=VCIx2, VGH=VCIx7, VGL=-VCIx3
	//--------------VCOM-------------------------------------
	LCD_Write_Cmd (ILI9341_VCOM1); // vcom control
	LCD_Write_Data   (0x35); // Set the VCOMH voltage (0x35 = 4.025v)
	LCD_Write_Data   (0x3e); // Set the VCOML voltage (0x3E = -0.950v)
	LCD_Write_Cmd (ILI9341_VCOM2); // vcom control
	LCD_Write_Data   (0xbe);

	//------------memory access control------------------------
	LCD_Write_Cmd (ILI9341_MAC); // memory access control
	LCD_Write_Data(0x48);

	LCD_Write_Cmd (ILI9341_PIXEL_FORMAT); // pixel format set
	LCD_Write_Data   (0x55); // 16bit /pixel

	LCD_Write_Cmd(ILI9341_FRC);
	LCD_Write_Data(0);
	LCD_Write_Data(0x1F);
	//-------------ddram ----------------------------
	LCD_Write_Cmd (ILI9341_COLUMN_ADDR); // column set
	LCD_Write_Data   (0x00); // x0_HIGH---0
	LCD_Write_Data   (0x00); // x0_LOW----0
	LCD_Write_Data   (0x00); // x1_HIGH---240
	LCD_Write_Data   (0x1D); // x1_LOW----240
	LCD_Write_Cmd (ILI9341_PAGE_ADDR); // page address set
	LCD_Write_Data   (0x00); // y0_HIGH---0
	LCD_Write_Data   (0x00); // y0_LOW----0
	LCD_Write_Data   (0x00); // y1_HIGH---320
	LCD_Write_Data   (0x27); // y1_LOW----320

	LCD_Write_Cmd (ILI9341_TEARING_OFF); // tearing effect off
	//LCD_write_cmd(ILI9341_TEARING_ON); // tearing effect on
	//LCD_write_cmd(ILI9341_DISPLAY_INVERSION); // display inversion
	LCD_Write_Cmd (ILI9341_Entry_Mode_Set); // entry mode set
	// Deep Standby Mode: OFF
	// Set the output level of gate driver G1-G320: Normal display
	// Low voltage detection: Disable
	LCD_Write_Data   (0x07);
	//-----------------display------------------------
	LCD_Write_Cmd (ILI9341_DFC); // display function control
	//Set the scan mode in non-display area
	//Determine source/VCOM output in a non-display area in the partial display mode
	LCD_Write_Data   (0x0a);
	//Select whether the liquid crystal type is normally white type or normally black type
	//Sets the direction of scan by the gate driver in the range determined by SCN and NL
	//Select the shift direction of outputs from the source driver
	//Sets the gate driver pin arrangement in combination with the GS bit to select the optimal scan mode for the module
	//Specify the scan cycle interval of gate driver in non-display area when PTG to select interval scan
	LCD_Write_Data   (0x82);
	// Sets the number of lines to drive the LCD at an interval of 8 lines
	LCD_Write_Data   (0x27);
	LCD_Write_Data   (0x00); // clock divisor

	LCD_Write_Cmd (ILI9341_SLEEP_OUT); // sleep out
	delay(100);
	LCD_Write_Cmd (ILI9341_DISPLAY_ON); // display on
	delay(100);
	LCD_Write_Cmd (ILI9341_GRAM); // memory write
	delay(5);

}

//set the address of the pixel in the memory 
void static setAddrWindow(uint8_t x0, uint8_t y0, uint8_t x1, uint8_t y1)
{

	LCD_Write_Cmd(0x2A); // Column addr set
	LCD_Write_Data(0x00);
	LCD_Write_Data(x0+ColStart);     // XSTART
	LCD_Write_Data(0x00);
	LCD_Write_Data(x1+ColStart);     // XEND

	LCD_Write_Cmd(0x2B); // Row addr set
	LCD_Write_Data(0x00);
	LCD_Write_Data(y0+RowStart);     // YSTART
	LCD_Write_Data(0x00);
	LCD_Write_Data(y1+RowStart);     // YEND

	LCD_Write_Cmd(0x2C); // write to RAM
}

//internally needed function to push 16-bit color as 2 8-bit data
void static pushColor(uint16_t color)
{
	LCD_Write_Data((uint8_t)(color >> 8));
	LCD_Write_Data((uint8_t)color);
}

//set cursor function
void ILI9341_SetCursorPosition(uint16_t x1, uint16_t y1, uint16_t x2, uint16_t y2)
{
	LCD_Write_Cmd (ILI9341_COLUMN_ADDR);
	LCD_Write_Data(x1>>8);
	LCD_Write_Data(x1 & 0xFF);
	LCD_Write_Data(x2>>8);
	LCD_Write_Data(x2 & 0xFF);
	LCD_Write_Cmd (ILI9341_PAGE_ADDR);
	LCD_Write_Data(y1>>8);
	LCD_Write_Data(y1 & 0xFF);
	LCD_Write_Data(y2>>8);
	LCD_Write_Data(y2 & 0xFF);
	LCD_Write_Cmd (ILI9341_GRAM);
}

void ILI9341_DrawPixel(uint16_t x, uint16_t y, uint16_t color)
{
	ILI9341_SetCursorPosition(x, y, x, y);
	LCD_Write_Data(color>>8);
	LCD_Write_Data(color&0xFF);
}

void ILI9341_Fill(uint16_t color)
{
	uint32_t n = ILI9341_PIXEL_COUNT;
	uint16_t myColor = 0xFF;
	
	if(rotationNum==1 || rotationNum==3)
	{
		ILI9341_SetCursorPosition(0, 0,   ILI9341_WIDTH -1, ILI9341_HEIGHT -1);
	}
	else if(rotationNum==2 || rotationNum==4)
	{
		ILI9341_SetCursorPosition(0, 0, ILI9341_HEIGHT -1, ILI9341_WIDTH -1);
	}
	
	
	while (n)
	{
		n--;
		LCD_Write_Data(color>>8);
		LCD_Write_Data(color&0xff);
	}
}



void ILI9341_Fill_Rect(unsigned int x0,unsigned int y0, unsigned int x1,unsigned int y1, uint16_t color) { 
	uint32_t n = ((x1+1)-x0)*((y1+1)-y0);
	if (n>ILI9341_PIXEL_COUNT) n=ILI9341_PIXEL_COUNT;
	ILI9341_SetCursorPosition(x0, y0, x1, y1);
	while (n)
	{
		n--;
		LCD_Write_Data(color>>8);
		LCD_Write_Data(color&0xff);
	}
}

void ILI9341_drawCircle(int16_t x0, int16_t y0, int16_t r, uint16_t color)
{
	int16_t f = 1 - r;
	int16_t ddF_x = 1;
	int16_t ddF_y = -2 * r;
	int16_t x = 0;
	int16_t y = r;

	ILI9341_DrawPixel(x0  , y0+r, color);
	ILI9341_DrawPixel(x0  , y0-r, color);
	ILI9341_DrawPixel(x0+r, y0  , color);
	ILI9341_DrawPixel(x0-r, y0  , color);

	while (x<y)
	{
		if (f >= 0)
		{
			y--;
			ddF_y += 2;
			f += ddF_y;
		}
		x++;
		ddF_x += 2;
		f += ddF_x;

		ILI9341_DrawPixel(x0 + x, y0 + y, color);
		ILI9341_DrawPixel(x0 - x, y0 + y, color);
		ILI9341_DrawPixel(x0 + x, y0 - y, color);
		ILI9341_DrawPixel(x0 - x, y0 - y, color);
		ILI9341_DrawPixel(x0 + y, y0 + x, color);
		ILI9341_DrawPixel(x0 - y, y0 + x, color);
		ILI9341_DrawPixel(x0 + y, y0 - x, color);
		ILI9341_DrawPixel(x0 - y, y0 - x, color);
	}
}
static void drawCircleHelper( int16_t x0, int16_t y0, int16_t r, uint8_t cornername, uint16_t color)
{
	int16_t f     = 1 - r;
	int16_t ddF_x = 1;
	int16_t ddF_y = -2 * r;
	int16_t x     = 0;
	int16_t y     = r;

	while (x<y)
	{
		if (f >= 0)
		{
			y--;
			ddF_y += 2;
			f += ddF_y;
		}
		x++;
		ddF_x += 2;
		f+= ddF_x;
		if (cornername & 0x4)
		{
			ILI9341_DrawPixel(x0 + x, y0 + y, color);
			ILI9341_DrawPixel(x0 + y, y0 + x, color);
		}
		if (cornername & 0x2) {
				ILI9341_DrawPixel(x0 + x, y0 - y, color);
				ILI9341_DrawPixel(x0 + y, y0 - x, color);
		}
		if (cornername & 0x8) {
			ILI9341_DrawPixel(x0 - y, y0 + x, color);
			ILI9341_DrawPixel(x0 - x, y0 + y, color);
		}
		if (cornername & 0x1)
		{
			ILI9341_DrawPixel(x0 - y, y0 - x, color);
			ILI9341_DrawPixel(x0 - x, y0 - y, color);
		}
	}
}
static void fillCircleHelper(int16_t x0, int16_t y0, int16_t r, uint8_t cornername, int16_t delta, uint16_t color)
{
	int16_t f     = 1 - r;
	int16_t ddF_x = 1;
	int16_t ddF_y = -2 * r;
	int16_t x     = 0;
	int16_t y     = r;

	while (x<y)
	{
		if (f >= 0)
		{
			y--;
			ddF_y += 2;
			f+= ddF_y;
		}
		x++;
		ddF_x += 2;
		f += ddF_x;

		if (cornername & 0x1)
		{
			ILI9341_drawFastVLine(x0+x, y0-y, 2*y+1+delta, color);
			ILI9341_drawFastVLine(x0+y, y0-x, 2*x+1+delta, color);
		}
		if (cornername & 0x2)
		{
			ILI9341_drawFastVLine(x0-x, y0-y, 2*y+1+delta, color);
			ILI9341_drawFastVLine(x0-y, y0-x, 2*x+1+delta, color);
		}
	}
}
void ILI9341_fillCircle(int16_t x0, int16_t y0, int16_t r, uint16_t color)
{
	ILI9341_drawFastVLine(x0, y0-r, 2*r+1, color);
	fillCircleHelper(x0, y0, r, 3, 0, color);
}
void ILI9341_drawLine(int16_t x0, int16_t y0, int16_t x1, int16_t y1, uint16_t color)
{
	int16_t steep = abs(y1 - y0) > abs(x1 - x0);
	if (steep)
	{
		swap(x0, y0);
		swap(x1, y1);
	}

	if (x0 > x1)
	{
		swap(x0, x1);
		swap(y0, y1);
	}

	int16_t dx, dy;
	dx = x1 - x0;
	dy = abs(y1 - y0);

	int16_t err = dx / 2;
	int16_t ystep;

	if (y0 < y1)
	{
		ystep = 1;
	}
	else
	{
		ystep = -1;
	}

	for (; x0<=x1; x0++)
	{
		if (steep)
		{
			ILI9341_DrawPixel(y0, x0, color);
		}
		else
		{
			ILI9341_DrawPixel(x0, y0, color);
		}
		err -= dy;
		if (err < 0)
		{
			y0 += ystep;
			err += dx;
		}
	}
}	

void ILI9341_drawFastHLine(int16_t x, int16_t y, int16_t w, uint16_t color)
{
	ILI9341_drawLine(x, y, x+w-1, y, color);
}

void ILI9341_drawFastVLine(int16_t x, int16_t y, int16_t h, uint16_t color)
{
	ILI9341_drawLine(x, y, x, y+h-1, color);
}
//10. Triangle drawing
void ILI9341_drawTriangle(int16_t x0, int16_t y0, int16_t x1, int16_t y1, int16_t x2, int16_t y2, uint16_t color)
{
	ILI9341_drawLine(x0, y0, x1, y1, color);
	ILI9341_drawLine(x1, y1, x2, y2, color);
	ILI9341_drawLine(x2, y2, x0, y0, color);
}
void ILI9341_fillTriangle(int16_t x0, int16_t y0, int16_t x1, int16_t y1, int16_t x2, int16_t y2, uint16_t color)
{
	int16_t a, b, y, last;

	// Sort coordinates by Y order (y2 >= y1 >= y0)
	if (y0 > y1) {
	swap(y0, y1); swap(x0, x1);
	}
	if (y1 > y2) {
	swap(y2, y1); swap(x2, x1);
	}
	if (y0 > y1) {
	swap(y0, y1); swap(x0, x1);
	}

	if(y0 == y2) { // Handle awkward all-on-same-line case as its own thing
	a = b = x0;
	if(x1 < a)      a = x1;
	else if(x1 > b) b = x1;
	if(x2 < a)      a = x2;
	else if(x2 > b) b = x2;
	ILI9341_drawFastHLine(a, y0, b-a+1, color);
	return;
	}

	int16_t
	dx01 = x1 - x0,
	dy01 = y1 - y0,
	dx02 = x2 - x0,
	dy02 = y2 - y0,
	dx12 = x2 - x1,
	dy12 = y2 - y1,
	sa   = 0,
	sb   = 0;

	// For upper part of triangle, find scanline crossings for segments
	// 0-1 and 0-2.  If y1=y2 (flat-bottomed triangle), the scanline y1
	// is included here (and second loop will be skipped, avoiding a /0
	// error there), otherwise scanline y1 is skipped here and handled
	// in the second loop...which also avoids a /0 error here if y0=y1
	// (flat-topped triangle).
	if(y1 == y2) last = y1;   // Include y1 scanline
	else         last = y1-1; // Skip it

	for(y=y0; y<=last; y++) {
	a   = x0 + sa / dy01;
	b   = x0 + sb / dy02;
	sa += dx01;
	sb += dx02;

	if(a > b) swap(a,b);
	ILI9341_drawFastHLine(a, y, b-a+1, color);
	}

	// For lower part of triangle, find scanline crossings for segments
	// 0-2 and 1-2.  This loop is skipped if y1=y2.
	sa = dx12 * (y - y1);
	sb = dx02 * (y - y0);
	for(; y<=y2; y++) {
	a   = x1 + sa / dy12;
	b   = x0 + sb / dy02;
	sa += dx12;
	sb += dx02;

	if(a > b) swap(a,b);
	ILI9341_drawFastHLine(a, y, b-a+1, color);
	}
}

void ILI9341_setRotation(uint8_t rotate)
{
	switch(rotate)
	{
	case 1:
	rotationNum = 1;
	LCD_Write_Cmd(ILI9341_MEMCONTROL);
	LCD_Write_Data(ILI9341_MADCTL_MY | ILI9341_MADCTL_BGR);
	break;
	case 2:
	rotationNum = 2;
	LCD_Write_Cmd(ILI9341_MEMCONTROL);
	LCD_Write_Data(ILI9341_MADCTL_MV | ILI9341_MADCTL_BGR);
	break;
	case 3:
	rotationNum = 3;
	LCD_Write_Cmd(ILI9341_MEMCONTROL);
	LCD_Write_Data(ILI9341_MADCTL_MX | ILI9341_MADCTL_BGR);
	break;
	case 4:
	rotationNum = 4;
	LCD_Write_Cmd(ILI9341_MEMCONTROL);
	LCD_Write_Data(ILI9341_MADCTL_MX | ILI9341_MADCTL_MY | ILI9341_MADCTL_MV | ILI9341_MADCTL_BGR);
	break;
	default:
	rotationNum = 1;
	LCD_Write_Cmd(ILI9341_MEMCONTROL);
	LCD_Write_Data(ILI9341_MADCTL_MY | ILI9341_MADCTL_BGR);
	break;
	}
}

void ILI9341_DrawChar(int16_t x, int16_t y, char c, int16_t textColor, int16_t bgColor, uint8_t size){
	uint8_t line; // horizontal row of pixels of character
	int32_t col, row, i, j;// loop indices
	if(((x + 5*size - 1) >= ILI9341_WIDTH)  || // Clip right
	((y + 8*size - 1) >= ILI9341_HEIGHT) || // Clip bottom
	((x + 5*size - 1) < 0)        || // Clip left
	((y + 8*size - 1) < 0)){         // Clip top
	return;
	}

	setAddrWindow(x, y, x+6*size-1, y+8*size-1);

	line = 0x01;        // print the top row first
	// print the rows, starting at the top
	for(row=0; row<8; row=row+1){
	for(i=0; i<size; i=i+1){
	// print the columns, starting on the left
	for(col=0; col<5; col=col+1){
	if(Font[(c*5)+col]&line){
	// bit is set in Font, print pixel(s) in text color
	for(j=0; j<size; j=j+1){
	pushColor(textColor);
	}
	} else{
	// bit is cleared in Font, print pixel(s) in background color
	for(j=0; j<size; j=j+1){
	pushColor(bgColor);
	}
	}
	}
	// print blank column(s) to the right of character
	for(j=0; j<size; j=j+1){
	pushColor(bgColor);
	}
	}
	line = line<<1;   // move up to the next row
	}
}
uint16_t ILI9341_Color565(uint8_t r, uint8_t g, uint8_t b) {
	return ((b & 0xF8) << 8) | ((g & 0xFC) << 3) | (r >> 3);
}

uint32_t ILI9341_DrawString(uint16_t x, uint16_t y, char *pt, int16_t textColor, int16_t BG,uint16_t size){
	uint32_t count = 0;

	while(*pt!='\0')
	{

		ILI9341_DrawChar(x*6*size, y*10*size, *pt, textColor, BG, size);
		pt++;
		x = x+1;
		count++;
	}
	return count;  // number of characters printed
}

4. Code:

You may download the source code from here:

ILI9341Download

5. Demo:

In main.c:

#include "LCD_Pins.h"
#include "ILI9341.h"


int main(void)
{
	delay_init(180000000);
	LCD_Pin_Init();
	LCD_SPI_Init();
	ILI9341_Init();
	ILI9341_setRotation(2);
	ILI9341_Fill(COLOR_RED);

	while(1)
	{
		ILI9341_Fill(COLOR_YELLOW);
		ILI9341_Fill(COLOR_PURPLE);

	}
}

Upload the code and you should get the following:

Next, touch interface.

Happy coding 🙂

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