{"id":2294,"date":"2024-01-21T05:31:08","date_gmt":"2024-01-21T05:31:08","guid":{"rendered":"https:\/\/blog.embeddedexpert.io\/?p=2294"},"modified":"2024-01-21T06:49:23","modified_gmt":"2024-01-21T06:49:23","slug":"getting-started-with-lvgl-part-3-touch-integration","status":"publish","type":"post","link":"https:\/\/blog.embeddedexpert.io\/?p=2294","title":{"rendered":"Getting Started with LvGL Part 3: Touch Integration"},"content":{"rendered":"\n
\"\"<\/figure><\/div>\n\n\n\n

<\/p>\n\n\n\n

In the pervious guide (here<\/a>), we have successfully integrated LCD. In part 3, we shall integrate the touch part of the LCD.<\/p>\n\n\n\n

<\/p>\n\n\n\n

10. Touch Connection:<\/h2>\n\n\n\n

The connection of Touch pins as following:<\/p>\n\n\n\n

\"\"<\/figure><\/div>\n\n\n\n

<\/p>\n\n\n\n

ILI9341<\/td>STM32F767Zi Nucleo-144<\/td><\/tr>
T_CLK<\/td>PB13<\/td><\/tr>
T_CS<\/td>PA3<\/td><\/tr>
T_DIN<\/td>PC2<\/td><\/tr>
T_OUT<\/td>PB15<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

PB13, PB15 and PC2 are for SPI2 peripheral of the STM32F767Zi<\/p>\n\n\n\n

11. Initialize SPI2:<\/h2>\n\n\n\n

<\/p>\n\n\n\n

Create new source and header file with name of SPI2.c and SPI2.h respectively:<\/p>\n\n\n\n

Within the header file:<\/p>\n\n\n\n

#ifndef SPI2_H_\n#define SPI2_H_\n\n\n#include "stdint.h"\n\nvoid SPI2_Pins_Init(void);\nvoid SPI2_Init(void);\nvoid SPI2_TX(uint8_t *data,uint32_t size);\nvoid SPI2_RX (uint8_t * data, uint8_t length);\n\n\n\n\n#endif \/* SPI2_H_ *\/<\/pre><\/div>\n\n\n\n
<\/p>\n\n\n\n
In the source file:<\/p>\n\n\n\n
#include "SPI2.h"\n#include "stm32f7xx.h"\n\n\n\n#define SPI2_AF 0x05\n\n\nvoid SPI2_Pins_Init(void)\n{\n\tRCC->AHB1ENR|=RCC_AHB1ENR_GPIOBEN|RCC_AHB1ENR_GPIOCEN;\n\n\tGPIOB->MODER|=GPIO_MODER_MODER13_1|GPIO_MODER_MODER15_1;\n\tGPIOB->MODER&=~(GPIO_MODER_MODER13_0|GPIO_MODER_MODER15_0);\n\n\tGPIOB->OSPEEDR|=GPIO_OSPEEDR_OSPEEDR15|GPIO_OSPEEDR_OSPEEDR13;\n\n\tGPIOB->AFR[1]|=(SPI2_AF<<GPIO_AFRH_AFRH5_Pos)|(SPI2_AF<<GPIO_AFRH_AFRH7_Pos);\n\n\n\n\tGPIOC->MODER|=GPIO_MODER_MODER2_1;\n\tGPIOC->MODER&=~(GPIO_MODER_MODER2_0);\n\n\tGPIOC->OSPEEDR|=GPIO_OSPEEDR_OSPEEDR2;\n\n\tGPIOC->AFR[0]|=(SPI2_AF<<GPIO_AFRL_AFRL2_Pos);\n\n}\n\n\nvoid SPI2_Init(void)\n{\n\n\tRCC->APB1ENR|=RCC_APB1ENR_SPI2EN;\n\n\t\/\/software slave management\n\tSPI2->CR1|=SPI_CR1_SSM|SPI_CR1_SSI;\n\n\t\/*Set clock to fPCLK\/16*\/\n\tSPI2->CR1 |=(SPI_CR1_BR_0|SPI_CR1_BR_1);\n\n\t\/\/ set SPI as master mode\n\tSPI2->CR1|=SPI_CR1_MSTR;\n\n\t\/*Set CPOL to 0 and CPHA to 0*\/\n\tSPI2->CR1 &=~SPI_CR1_CPOL;\n\tSPI2->CR1 &=~SPI_CR1_CPHA;\n\n\t\/*Set data size to 8-bit*\/\n\tSPI2->CR2&=~(SPI_CR2_DS_Msk);\n\tSPI2->CR2|=(0x07<<SPI_CR2_DS_Pos);\n\n\tSPI2->CR2|=SPI_CR2_FRXTH;\n\n\tSPI2->CR1|=SPI_CR1_SPE;\n\n}\n\nvoid SPI2_TX(uint8_t *data,uint32_t size)\n{\n\n\n\n\tuint32_t i=0;\n\twhile(i<size)\n\t{\n\t\t\/*Wait until TXE is set*\/\n\t\twhile(!(SPI2->SR & (SPI_SR_TXE)))\n\t\t{}\n\n\t\t\/*Write the data to the data register*\/\n\t\t*((volatile uint8_t *)&SPI2->DR) = data[i];\n\t\ti++;\n\t}\n\t\/*Wait until TXE is set*\/\n\twhile(!(SPI2->SR & (SPI_SR_TXE))){}\n\n\t\/*Wait for BUSY flag to reset*\/\n\twhile((SPI2->SR & (SPI_SR_BSY))){}\n\n\t\/*Clear OVR flag*\/\n\t(void)SPI2->DR;\n\t(void)SPI2->SR;\n\n}\n\n\nvoid SPI2_RX (uint8_t * data, uint8_t length)\n{\n\n\twhile(length)\n\t{\n\t\t\/*Send dummy data*\/\n\t\t*((volatile uint8_t *)&SPI2->DR) =0xFF;\n\n\t\t\/*Wait for RXNE flag to be set*\/\n\t\twhile(!(SPI2->SR & (SPI_SR_RXNE))){}\n\n\t\t\/*Read data from data register*\/\n\t\t*data++ = *((volatile uint8_t *)&SPI2->DR);\n\t\tlength--;\n\t}\n\n}\n<\/pre><\/div>\n\n\n\n
We shall read the touch in polling mode.<\/p>\n\n\n\n
<\/p>\n\n\n\n
12. CS Pin Initialization:<\/h2>\n\n\n\n
Create new source and header file with name of TouchPins.c and TouchPins.h<\/p>\n\n\n\n
This file will handle the CS pin initialization.<\/p>\n\n\n\n
Within the header file:<\/p>\n\n\n\n
#ifndef TOUCHPINS_H_\n#define TOUCHPINS_H_\n\n#include "stdint.h"\n\nvoid TouchPin_CS_Init(void);\nvoid TouchPin_CS_Low(void);\nvoid TouchPin_CS_High(void);\n\n\n#endif \/* TOUCHPINS_H_ *\/\n<\/pre><\/div>\n\n\n\n
In source file:<\/p>\n\n\n\n
#include "TouchPins.h"\n#include "stm32f7xx.h"\n\n\nvoid TouchPin_CS_Init(void)\n{\n\tRCC->AHB1ENR|=RCC_AHB1ENR_GPIOAEN;\n\n\tGPIOA->MODER|=GPIO_MODER_MODER3_0;\n\tGPIOA->MODER&=~GPIO_MODER_MODER3_1;\n\n\tGPIOA->BSRR=GPIO_BSRR_BS3;\n\n\n}\n\nvoid TouchPin_CS_Low(void)\n{\n\tGPIOA->BSRR=GPIO_BSRR_BR3;\n}\n\nvoid TouchPin_CS_High(void)\n{\n\tGPIOA->BSRR=GPIO_BSRR_BS3;\n}\n<\/pre><\/div>\n\n\n\n
<\/p>\n\n\n\n
13. Touchpanel initialization:<\/h2>\n\n\n\n
Create new source and header file with name of xpt2046.c and xpt2046.h respectively.<\/p>\n\n\n\n
Within the header file:<\/p>\n\n\n\n
#ifndef INC_TOUCH_H_\n#define INC_TOUCH_H_\n\n#include "stdint.h"\n\n\n#define TP_PRES_DOWN 0x80\n#define TP_CATH_PRES 0x40\n#define CMD_RDX 0xD0\n#define CMD_RDY 0x90\n#define XPT_XMIN 300\n#define XPT_YMIN 300\n#define XPT_XMAX 3600\n#define XPT_YMAX 3400\n#define XPT_WIDTH (XPT_XMAX - XPT_XMIN)\n#define XPT_HEIGHT (XPT_YMAX - XPT_YMIN)\n\nvoid XPT2046_Init(void);\nvoid XPT2046_Update(uint16_t *x, uint16_t *y);\nuint8_t XPT2046_IsReasonable(uint16_t x, uint16_t y);\n\n\n\n#endif \/* INC_TOUCH_H_ *\/\n<\/pre><\/div>\n\n\n\n
Within the source file:<\/p>\n\n\n\n
Taken from arduino library and modified.<\/p>\n\n\n\n
#include "xpt2046.h"\n#include "time_base.h"\n#include "TouchPins.h"\n#include "SPI2.h"\n\n\n\n\nstatic void XPT2046_SetCS(void)\n{\n\tTouchPin_CS_High();\n}\n\nstatic void XPT2046_ResetCS(void)\n{\n\tTouchPin_CS_Low();\n}\n\n\n\/**********************************************************************************************************\/\n\n#define T_IRQ XPT2046_ReadIRQ()\n#define T_CS_ON XPT2046_SetCS()\n#define T_CS_OFF XPT2046_ResetCS()\n\n#define READ_TIMES \t5\n#define LOST_VAL \t1\n#define ERR_RANGE 50\n#define Z_THRESHOLD     400\n#define Z_THRESHOLD_INT\t75\n#define MSEC_THRESHOLD  3\n\nstatic uint8_t XPT2046_initilazed = 0;\n\n\nstatic uint16_t XPT2046_Read_AD(uint8_t CMD)\n{\n\tuint8_t num[2];\n\tuint16_t ret;\n\n\tT_CS_OFF;\n\tSPI2_TX(&CMD,1);\n\tdelay(6);\n\n\tSPI2_RX(num, 2);\n\tT_CS_ON;\n\n\tret = num[0] << 8 | num[1];\n\tret >>= 3;\n\tret &= (1<<12)-1;\n\n\treturn ret;\n}\n\nstatic int16_t besttwoavg( int16_t x , int16_t y , int16_t z ) {\n  int16_t da, db, dc;\n  int16_t reta = 0;\n  if ( x > y ) da = x - y; else da = y - x;\n  if ( x > z ) db = x - z; else db = z - x;\n  if ( z > y ) dc = z - y; else dc = y - z;\n\n  if ( da <= db && da <= dc ) reta = (x + y) >> 1;\n  else if ( db <= da && db <= dc ) reta = (x + z) >> 1;\n  else reta = (y + z) >> 1;   \/\/    else if ( dc <= da && dc <= db ) reta = (x + y) >> 1;\n\n  return (reta);\n}\n\nvoid XPT2046_Init(void)\n{\n\tSPI2_Pins_Init();\n\tSPI2_Init();\n\tTouchPin_CS_Init();\n\n\n\tXPT2046_initilazed = 1;\n}\n\nvoid XPT2046_Update(uint16_t *x, uint16_t *y)\n{\n\tint16_t data[6];\n\tstatic uint32_t ptime = 0;\n\n\tif (XPT2046_initilazed == 0) {\n\t\treturn;\n\t}\n\n\tif (Tick_Get() - ptime < MSEC_THRESHOLD) {\n\t\treturn;\n\t}\n\n\tint16_t z1 = XPT2046_Read_AD(0xb1); \/\/ z1\n\tint32_t z = z1 + 4095;\n\tint16_t z2 = XPT2046_Read_AD(0xc1); \/\/ z2\n\tz -= z2;\n\tif (z >= Z_THRESHOLD) {\n\t\tXPT2046_Read_AD(0x91);  \/\/ dummy 1st X measure\n\t\tdata[0] = XPT2046_Read_AD(0x91);\n\t\tdata[1] = XPT2046_Read_AD(0xd1);\n\t\tdata[2] = XPT2046_Read_AD(0x91);\n\t\tdata[3] = XPT2046_Read_AD(0xd1);\n\t} else {\n\t\tdata[0] = data[1] = data[2] = data[3] = 0;\n\t}\n\tdata[4] = XPT2046_Read_AD(0x91);\n\tdata[5] = XPT2046_Read_AD(0xd0);\n\tptime = Tick_Get();\n\tif (z < 0) z = 0;\n\tint16_t intx = besttwoavg( data[1], data[3], data[5] );\n\tint16_t inty = besttwoavg( data[0], data[2], data[4] );\n\tif (z >= Z_THRESHOLD) {\n\t\t*x = intx;\n\t\t*y = inty;\n\t}\n}\n\nuint8_t XPT2046_IsReasonable(uint16_t x, uint16_t y)\n{\n\tif (x >= XPT_XMIN && x <= XPT_XMAX && y >= XPT_YMIN && y <= XPT_YMAX) {\n\t\treturn 1;\n\t}\n\treturn 0;\n}\n<\/pre><\/div>\n\n\n\n
<\/p>\n\n\n\n
Note: The these values are near enough to make the touch screen work. In your application, you will need to implement touch screen calibration or calibrate before release.<\/p>\n\n\n\n
<\/p>\n\n\n\n
14. Rotating the LCD:<\/h2>\n\n\n\n
Since this driver will only work in landscape mode, we shall rotate the LCD by 90.<\/p>\n\n\n\n
In ILI9341.c file, modify the memory access control (MAC) to become as following:<\/p>\n\n\n\n
\tLCD_Write_Cmd (ILI9341_MAC); \/\/ memory access control\n\tLCD_Write_Data((1<<3)|(1U<<5)|(1<<2));<\/pre><\/div>\n\n\n\n
In LCDController.c, we shall change the dimensions as following:<\/p>\n\n\n\n
#define MY_DISP_HOR_RES 320\n\n\n#define MY_DISP_VER_RES 240<\/pre><\/div>\n\n\n\n
Thats all for rotating screen.<\/p>\n\n\n\n
<\/p>\n\n\n\n
15. Touch Integration:<\/h2>\n\n\n\n
Create new source and header file with name of TouchController.c and TouchController.h.<\/p>\n\n\n\n
Within the header file:<\/p>\n\n\n\n
#ifndef INC_TOUCHCONTROLLER_H_\n#define INC_TOUCHCONTROLLER_H_\n\n\/*********************\n *      INCLUDES\n *********************\/\n#include "lvgl.h"\n\n\/*********************\n *      DEFINES\n *********************\/\n\n\/**********************\n *      TYPEDEFS\n **********************\/\n\n\/**********************\n * GLOBAL PROTOTYPES\n **********************\/\nvoid lv_port_indev_init(void);\n\n\/**********************\n *      MACROS\n **********************\/\n\n\n\n#endif \/* INC_TOUCHCONTROLLER_H_ *\/<\/pre><\/div>\n\n\n\n
<\/p>\n\n\n\n
Within the source file:<\/p>\n\n\n\n
<\/p>\n\n\n\n
#include "TouchController.h"\n#include "lvgl.h"\n#include "stdio.h"\n#include "xpt2046.h"\n\n#include "ILI_9341.h"\n\/*********************\n *      DEFINES\n *********************\/\n\n\/**********************\n *      TYPEDEFS\n **********************\/\n\n\/**********************\n *  STATIC PROTOTYPES\n **********************\/\n\nstatic void touchpad_init(void);\nstatic void touchpad_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data);\nstatic bool touchpad_is_pressed(void);\nstatic void touchpad_get_xy(lv_coord_t * x, lv_coord_t * y);\n\n\n\/**********************\n *  STATIC VARIABLES\n **********************\/\nlv_indev_t * indev_touchpad;\n\n\n\/**********************\n *      MACROS\n **********************\/\n\n\/**********************\n *   GLOBAL FUNCTIONS\n **********************\/\n\nvoid lv_port_indev_init(void)\n{\n    \/**\n     * Here you will find example implementation of input devices supported by LittelvGL:\n     *  - Touchpad\n     *  - Mouse (with cursor support)\n     *  - Keypad (supports GUI usage only with key)\n     *  - Encoder (supports GUI usage only with: left, right, push)\n     *  - Button (external buttons to press points on the screen)\n     *\n     *  The `..._read()` function are only examples.\n     *  You should shape them according to your hardware\n     *\/\n\n    static lv_indev_drv_t indev_drv;\n\n    \/*------------------\n     * Touchpad\n     * -----------------*\/\n\n    \/*Initialize your touchpad if you have*\/\n    touchpad_init();\n\n    \/*Register a touchpad input device*\/\n    lv_indev_drv_init(&indev_drv);\n    indev_drv.type = LV_INDEV_TYPE_POINTER;\n    indev_drv.read_cb = touchpad_read;\n    indev_touchpad = lv_indev_drv_register(&indev_drv);\n}\n\n\/**********************\n *   STATIC FUNCTIONS\n **********************\/\n\n\nstatic void ConvXPTtoILI(uint16_t *x, uint16_t *y)\n{\n\tuint16_t tx,ty;\n\tty = (int16_t)(((int32_t)*x - XPT_YMIN) * ILI9341_HEIGHT \/ XPT_HEIGHT);\n\tty = (ty < 0) ? 0 : ty;\n\tty = (ty >= ILI9341_HEIGHT) ? ILI9341_HEIGHT-1 : ty;\n\n\ttx = (int16_t)(((int32_t)*y - XPT_XMIN) * ILI9341_WIDTH \/ XPT_WIDTH);\n\ttx = (tx < 0) ? 0 : tx;\n\ttx = (tx >= ILI9341_WIDTH) ? ILI9341_WIDTH-1 : tx;\n\t*y = ty;\n\t*x = ILI9341_WIDTH-tx;\n}\n\nstruct {\n\tlv_coord_t x;\n\tlv_coord_t y;\n}get_xy;\n\/*------------------\n * Touchpad\n * -----------------*\/\n\n\/*Initialize your touchpad*\/\nstatic void touchpad_init(void)\n{\n    XPT2046_Init();\n}\n\n\/*Will be called by the library to read the touchpad*\/\nstatic void touchpad_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data)\n{\n    static lv_coord_t last_x = 0;\n    static lv_coord_t last_y = 0;\n\n    \/*Save the pressed coordinates and the state*\/\n    if(touchpad_is_pressed()) {\n\n    \tlast_x = get_xy.x;\n    \tlast_y = get_xy.y;\n        data->state = LV_INDEV_STATE_PR;\n    }\n    else {\n        data->state = LV_INDEV_STATE_REL;\n    }\n\n    \/*Set the last pressed coordinates*\/\n    data->point.x = last_x;\n    data->point.y = last_y;\n}\n\n\n\/*Return true is the touchpad is pressed*\/\nstatic bool touchpad_is_pressed(void)\n{\n\tstatic uint16_t prevx = ILI9341_WIDTH;\n\tstatic uint16_t prevy = ILI9341_HEIGHT;\n\tuint16_t intx, inty;\n\tXPT2046_Update(&intx, &inty);\n\n\tif (XPT2046_IsReasonable(intx, inty))\n\t{\n\n\n\n\t\tConvXPTtoILI(&intx, &inty);\n\n\t\tif (intx != prevx || inty != prevy)\n\t\t{\n\t\t\tprevx = intx;\n\t\t\tprevy = inty;\n\t\t\tget_xy.x = (int32_t)intx;\n\t\t\tget_xy.y = (int32_t)inty;\n\t\t\treturn true;\n\t\t}\n\t}\n\treturn 0;\n}\n\n\/*Get the x and y coordinates if the touchpad is pressed*\/\nstatic void touchpad_get_xy(lv_coord_t * x, lv_coord_t * y)\n{\n    \/*Your code comes here*\/\n\n    (*x) = 0;\n    (*y) = 0;\n}\n<\/pre><\/div>\n\n\n\n
<\/p>\n\n\n\n
Thats all for the touch integration.<\/p>\n\n\n\n
<\/p>\n\n\n\n
16. Main code:<\/h2>\n\n\n\n
Include the touch controller header file<\/p>\n\n\n\n
#include "TouchController.h"<\/pre><\/div>\n\n\n\n
Call the touch initialization after the display initialization:<\/p>\n\n\n\n
lv_port_indev_init();<\/pre><\/div>\n\n\n\n
<\/p>\n\n\n\n
17. Results:<\/h2>\n\n\n\n
\n