前半部分是显示效果，后半部分是代码。
gt9147_init() 初始化，打印的数据 ->
屏幕显示的数据 ->
历程源码中的 bsp_gt9147.c 文件 有几处需要修改，4.3寸屏幕 才能显示数据。
bsp_gt9147.h 文件不用修改。
/***************************************************************
Copyright © zuozhongkai Co., Ltd. 1998-2019. All rights reserved.
文件名 : bsp_gt9147.c
作者 : 左忠凯
版本 : V1.0
描述 : 触摸屏驱动文件,触摸芯片为GT9147。
其他 : 无
论坛 : www.openedv.com
日志 : 初版V1.0 2020/1/15 左忠凯创建
***************************************************************/
#include "bsp_gt9147.h"
#include "bsp_i2c.h"
#include "bsp_int.h"
#include "bsp_delay.h"
#include "stdio.h"
#include "bsp_lcd.h"
#include "bsp_lcdapi.h"
/*
* GT9147配置参数表
* 第一个字节为版本号(0X61),必须保证新的版本号大于等于GT9147内部
* flash原有版本号,才会更新配置.
*/
u8 GT9147_CFG_TBL[]=
{
0x41,0xe0,0x01,0x10,0x01,0x05,0x0d,0x00,0x01,0x08,
0x28,0x05,0x50,0x32,0x03,0x05,0x00,0x00,0xff,0xff,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x89,0x28,0x0a,
0x17,0x15,0x31,0x0d,0x00,0x00,0x02,0x9b,0x03,0x25,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x32,0x00,0x00,
0x00,0x0f,0x94,0x94,0xc5,0x02,0x07,0x00,0x00,0x04,
0x8d,0x13,0x00,0x5c,0x1e,0x00,0x3c,0x30,0x00,0x29,
0x4c,0x00,0x1e,0x78,0x00,0x1e,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x08,0x0a,0x0c,0x0e,0x10,0x12,0x14,0x16,
0x18,0x1a,0x00,0x00,0x00,0x00,0x1f,0xff,0xff,0xff,
0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
0xff,0xff,0x00,0x02,0x04,0x05,0x06,0x08,0x0a,0x0c,
0x0e,0x1d,0x1e,0x1f,0x20,0x22,0x24,0x28,0x29,0xff,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xff,0xff,
0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
0xff,0xff,0xff,0xff,
};
struct gt9147_dev_struc gt9147_dev;
int gt_init_fail = 0;
/*
* @description : 初始化触摸屏，其实就是初始化GT9147
* @param : 无
* @return : 无
*/
void gt9147_init(void)
{
volatile unsigned char temp[7]; // 修改这里
gpio_pin_config_t ctintpin_config;
gpio_pin_config_t ctretpin_config;
gt9147_dev.initfalg = GT9147_INIT_NOTFINISHED;
int i;
for( i = 0; i < 5; i++ )
{ /* 避免编译器自动赋值 */
gt9147_dev.x[i] = 0;
gt9147_dev.y[i] = 0;
}
gt9147_dev.point_num = 0;
/* 1、初始化IIC2 IO
* I2C2_SCL -> UART5_TXD
* I2C2_SDA -> UART5_RXD
*/
IOMUXC_SetPinMux(IOMUXC_UART5_TX_DATA_I2C2_SCL,1);
IOMUXC_SetPinMux(IOMUXC_UART5_RX_DATA_I2C2_SDA,1);
/* 配置I2C2 IO属性
*bit 16:0 HYS关闭
*bit [15:14]: 1 默认47K上拉
*bit [13]: 1 pull功能
*bit [12]: 1 pull/keeper使能
*bit [11]: 0 关闭开路输出
*bit [7:6]: 10 速度100Mhz
*bit [5:3]: 110 驱动能力为R0/6
*bit [0]: 1 高转换率
*/
IOMUXC_SetPinConfig(IOMUXC_UART5_TX_DATA_I2C2_SCL, 0x70B0);
IOMUXC_SetPinConfig(IOMUXC_UART5_RX_DATA_I2C2_SDA, 0X70B0);
/* 2、初始化触摸屏中断IO和复位IO */
IOMUXC_SetPinMux(IOMUXC_GPIO1_IO09_GPIO1_IO09,0); /* 复用为GPIO1_IO9 */
IOMUXC_SetPinMux(IOMUXC_SNVS_SNVS_TAMPER9_GPIO5_IO09,0);/* 复用为GPIO5_IO9 */
IOMUXC_SetPinConfig(IOMUXC_GPIO1_IO09_GPIO1_IO09,0x10B0);
IOMUXC_SetPinConfig(IOMUXC_SNVS_SNVS_TAMPER9_GPIO5_IO09,0X10B0);
/* 中断IO初始化 */
ctintpin_config.direction = kGPIO_DigitalOutput;
ctintpin_config.outputLogic = 1;
ctintpin_config.interruptMode = kGPIO_NoIntmode;
gpio_init(GPIO1, 9, &ctintpin_config);
/* 复位IO初始化 */
ctretpin_config.direction = kGPIO_DigitalOutput;
ctretpin_config.interruptMode = kGPIO_NoIntmode;
ctretpin_config.outputLogic = 1;
gpio_init(GPIO5, 9, &ctretpin_config);
/* 3、初始化I2C */
i2c_init(I2C2);
/* 4、初始化GT9147，要严格按照GT9147时序要求 */
gpio_pinwrite(GPIO5, 9, 0); /* 复位GT9147 */
delayms(10);
gpio_pinwrite(GPIO5, 9, 1); /* 停止复位GT9147 */
delayms(10);
gpio_pinwrite(GPIO1, 9, 0); /* 拉低INT引脚 */
delayms(100);
gt9147_read_len(GT9147_ADDR, GT_PID_REG, 6, (unsigned char *)temp);/* 读取产品ID */
temp[6] = temp[4];
temp[4] = 0;
printf("CTP ID:%s\r\n", temp); /* 打印ID */
printf("Default Ver:%#x\r\n",((temp[5]<<8) | temp[6])); /* 打印固件版本 */
/* 重新设置中断IO，配置为中断功能 */
IOMUXC_SetPinConfig(IOMUXC_GPIO1_IO09_GPIO1_IO09,0x0080);
ctintpin_config.direction = kGPIO_DigitalInput;
ctintpin_config.outputLogic=0;
if(temp[0] != 0x31)
{
temp[0]=gt9147_read_byte(GT9147_ADDR, 0x804D) & 0x3; /* 获取中断模式 */
printf("9xx\r\n");
}
else temp[0]=gt9147_read_byte(GT9147_ADDR, 0x8056) & 0x3;
switch(temp[0]) {
case 0x0:
printf("InterruptMode:IntRisingEdge\r\n");
ctintpin_config.interruptMode = kGPIO_IntRisingEdge;
break;
case 0x1:
printf("InterruptMode:IntFallingEdge\r\n");
ctintpin_config.interruptMode = kGPIO_IntFallingEdge;
break;
case 0x2:
printf("InterruptMode:IntLowLevel\r\n");
ctintpin_config.interruptMode = kGPIO_IntLowLevel;
break;
case 0x3:
printf("InterruptMode:IntHighLevel\r\n");
ctintpin_config.interruptMode = kGPIO_IntHighLevel;
break;
default : printf("InterruptMode: Error\r\n");
ctintpin_config.interruptMode = kGPIO_IntRisingOrFallingEdge;
break;
}
gpio_init(GPIO1, 9, &ctintpin_config);
if(gt9147_write_byte(GT9147_ADDR, GT_CTRL_REG, 0x02))
{
gt_init_fail = 1; //gt系列初始化失败
goto done;
}
delayms(10);
// 修改这里,使能中断之前，标记GT9147初始化完成
gt9147_dev.initfalg = GT9147_INIT_FINISHED; /* 标记GT9147初始化完成 */
gt9147_dev.intflag = 0;
gt9147_write_byte(GT9147_ADDR, GT_CTRL_REG, 0);
GIC_EnableIRQ(GPIO1_Combined_0_15_IRQn); /* 使能GIC中对应的中断 */
system_register_irqhandler(GPIO1_Combined_0_15_IRQn, (system_irq_handler_t)gt9147_irqhandler, NULL); /* 注册中断服务函数 */
gpio_enableint(GPIO1, 9); /* 使能GPIO1_IO09的中断功能 */
delayms(100);
done:
delayms(10);
}
/*
* @description : GPIO1_IO9最终的中断处理函数
* @param : 无
* @return : 无
*/
void gt9147_irqhandler(void)
{
if(gt9147_dev.initfalg == GT9147_INIT_FINISHED) // 触摸屏初始化完成
{
gt9147_dev.intflag = 1;
// 修改这里
unsigned char touch_status = gt9147_read_byte(GT9147_ADDR, GT_GSTID_REG);
if(touch_status & 0x80) // 第7位为1 表示有 有效触摸数据,此时再读取触摸点的坐标
{
gt9147_read_tpcoord(); // 读取当前 所有触摸点的坐标
/* 4.3寸屏幕，触摸芯片型号 gt9147，屏幕显示坐标数据 测试 */
#if 1
tftlcd_dev.forecolor = LCD_BLUE;
lcd_shownum(50 + 72, 110, gt9147_dev.point_num , 1, 16);
lcd_shownum(50 + 72, 130, gt9147_dev.x[0], 5, 16);
lcd_shownum(50 + 72, 150, gt9147_dev.y[0], 5, 16);
lcd_shownum(50 + 72, 170, gt9147_dev.x[1], 5, 16);
lcd_shownum(50 + 72, 190, gt9147_dev.y[1], 5, 16);
lcd_shownum(50 + 72, 210, gt9147_dev.x[2], 5, 16);
lcd_shownum(50 + 72, 230, gt9147_dev.y[2], 5, 16);
lcd_shownum(50 + 72, 250, gt9147_dev.x[3], 5, 16);
lcd_shownum(50 + 72, 270, gt9147_dev.y[3], 5, 16);
lcd_shownum(50 + 72, 290, gt9147_dev.x[4], 5, 16);
lcd_shownum(50 + 72, 310, gt9147_dev.y[4], 5, 16);
lcd_draw_big_point(gt9147_dev.x[0],gt9147_dev.y[0],LCD_BLACK);
lcd_draw_big_point(gt9147_dev.x[1],gt9147_dev.y[1],LCD_BLUE);
lcd_draw_big_point(gt9147_dev.x[2],gt9147_dev.y[2],LCD_RED);
lcd_draw_big_point(gt9147_dev.x[3],gt9147_dev.y[3],LCD_GREEN);
lcd_draw_big_point(gt9147_dev.x[4],gt9147_dev.y[4],LCD_YELLOW);
#endif
}
else{
}
}
gpio_clearintflags(GPIO1, 9); /* 清除中断标志位 */
}
/*
* @description : 向GT9147写入数据
* @param - addr: 设备地址
* @param - reg : 要写入的寄存器
* @param - data: 要写入的数据
* @return : 操作结果
*/
unsigned char gt9147_write_byte(unsigned char addr,unsigned int reg, unsigned char data)
{
unsigned char status=0;
unsigned char writedata=data;
struct i2c_transfer masterXfer;
/* 配置I2C xfer结构体 */
masterXfer.slaveAddress = addr; /* 设备地址 */
masterXfer.direction = kI2C_Write; /* 写入数据 */
masterXfer.subaddress = reg; /* 要写入的寄存器地址 */
masterXfer.subaddressSize = 2; /* 地址长度一个字节 */
masterXfer.data = &writedata; /* 要写入的数据 */
masterXfer.dataSize = 1; /* 写入数据长度1个字节 */
if(i2c_master_transfer(I2C2, &masterXfer))
status=1;
return status;
}
/*
* @description : 从GT9147读取一个字节的数据
* @param - addr: 设备地址
* @param - reg : 要读取的寄存器
* @return : 读取到的数据。
*/
unsigned char gt9147_read_byte(unsigned char addr,unsigned int reg)
{
unsigned char val=0;
struct i2c_transfer masterXfer;
masterXfer.slaveAddress = addr; /* 设备地址 */
masterXfer.direction = kI2C_Read; /* 读取数据 */
masterXfer.subaddress = reg; /* 要读取的寄存器地址 */
masterXfer.subaddressSize = 2; /* 地址长度一个字节 */
masterXfer.data = &val; /* 接收数据缓冲区 */
masterXfer.dataSize = 1; /* 读取数据长度1个字节 */
i2c_master_transfer(I2C2, &masterXfer);
return val;
}
/*
* @description : 从GT9147读取多个字节的数据
* @param - addr: 设备地址
* @param - reg : 要读取的开始寄存器地址
* @param - len : 要读取的数据长度.
* @param - buf : 读取到的数据缓冲区
* @return : 无
*/
void gt9147_read_len(unsigned char addr,unsigned int reg,unsigned int len,unsigned char *buf)
{
struct i2c_transfer masterXfer;
masterXfer.slaveAddress = addr; /* 设备地址 */
masterXfer.direction = kI2C_Read; /* 读取数据 */
masterXfer.subaddress = reg; /* 要读取的寄存器地址 */
masterXfer.subaddressSize = 2; /* 地址长度一个字节 */
masterXfer.data = buf; /* 接收数据缓冲区 */
masterXfer.dataSize = len; /* 读取数据长度1个字节 */
i2c_master_transfer(I2C2, &masterXfer);
}
/*
* @description : 向GT9147多个寄存器写入数据
* @param - addr: 设备地址
* @param - reg : 要写入的开始寄存器地址
* @param - len : 要写入的数据长度.
* @param - buf : 写入到的数据缓冲区
* @return : 无
*/
void gt9147_write_len(unsigned char addr,unsigned int reg,unsigned int len, unsigned char *buf)
{
struct i2c_transfer masterXfer;
masterXfer.slaveAddress = addr; /* 设备地址 */
masterXfer.direction = kI2C_Write; /* 读取数据 */
masterXfer.subaddress = reg; /* 要读取的寄存器地址 */
masterXfer.subaddressSize = 2; /* 地址长度一个字节 */
masterXfer.data = buf; /* 接收数据缓冲区 */
masterXfer.dataSize = len; /* 读取数据长度1个字节 */
i2c_master_transfer(I2C2, &masterXfer);
}
/*
* @description : 发送GT9147配置参数
* @param - mode: 0,参数不保存到flash
* 1,参数保存到flash
* @return : 无
*/
void gt9147_send_cfg(unsigned char mode)
{
unsigned char buf[2];
unsigned int i = 0;
buf[0] = 0;
buf[1] = mode; /* 是否写入到GT9147 FLASH? 即是否掉电保存 */
for(i = 0; i < (sizeof(GT9147_CFG_TBL)); i++) /* 计算校验和 */
buf[0] += GT9147_CFG_TBL[i];
buf[0] = (~buf[0]) + 1;
/* 发送寄存器配置 */
gt9147_write_len(GT9147_ADDR, GT_CFGS_REG, sizeof(GT9147_CFG_TBL), GT9147_CFG_TBL);
gt9147_write_len(GT9147_ADDR, GT_CHECK_REG, 2, buf);/* 写入校验和,配置更新标记 */
}
const u16 GT9147_TPX_TBL[5]={GT_TP1_REG,GT_TP2_REG,GT_TP3_REG,GT_TP4_REG,GT_TP5_REG};
/*
* @description : 读取当前所有触摸点的坐标
* @param : 无
* @return : 无
*/
void gt9147_read_tpcoord(void)
{
u8 buf[4];
u8 i = 0;
u8 regvalue = 0;
regvalue = gt9147_read_byte(GT9147_ADDR, GT_GSTID_REG);
gt9147_write_byte(GT9147_ADDR, GT_GSTID_REG, 0x00);
gt9147_dev.point_num = regvalue & 0XF; /* 计算读取了多少个点 */
/* 读取当前所有的触摸坐标值 */
for(i = 0; i < gt9147_dev.point_num; i++)
{
gt9147_read_len(GT9147_ADDR, GT9147_TPX_TBL[i], 4, buf); /* 读取坐标值 */
gt9147_dev.x[i] = ((u16)buf[1] << 8) + buf[0];
gt9147_dev.y[i] = (((u16)buf[3] << 8) + buf[2]);
}
}主函数 代码 ->
#include "bsp_clk.h"
#include "bsp_delay.h"
#include "bsp_led.h"
#include "bsp_beep.h"
#include "bsp_key.h"
#include "bsp_int.h"
#include "bsp_uart.h"
#include "bsp_lcd.h"
#include "bsp_lcdapi.h"
#include "bsp_rtc.h"
#include "bsp_ft5xx6.h"
#include "bsp_gt9147.h"
#include "stdio.h"
/*
* @description : 使能I.MX6U的硬件NEON和FPU
* @param : 无
* @return : 无
*/
void imx6ul_hardfpu_enable(void)
{
uint32_t cpacr;
uint32_t fpexc;
/* 使能NEON和FPU */
cpacr = __get_CPACR();
cpacr = (cpacr & ~(CPACR_ASEDIS_Msk | CPACR_D32DIS_Msk))
| (3UL << CPACR_cp10_Pos) | (3UL << CPACR_cp11_Pos);
__set_CPACR(cpacr);
fpexc = __get_FPEXC();
fpexc |= 0x40000000UL;
__set_FPEXC(fpexc);
}
/*
* @description : main函数
* @param : 无
* @return : 无
*/
int main(void)
{
unsigned char i = 0;
unsigned char state = OFF;
imx6ul_hardfpu_enable(); /* 使能I.MX6U的硬件浮点 */
int_init(); /* 初始化中断(一定要最先调用！) */
imx6u_clkinit(); /* 初始化系统时钟 */
delay_init(); /* 初始化延时 */
clk_enable(); /* 使能所有的时钟 */
led_init(); /* 初始化led */
beep_init(); /* 初始化beep */
uart_init(); /* 初始化串口，波特率115200 */
lcd_init(); /* 初始化LCD */
/* 初始化触摸屏 */
gt9147_init();
if(gt_init_fail==1) //判断gt系列初始化是否失败
{
ft5426_init();
}
tftlcd_dev.forecolor = LCD_RED;
lcd_show_string(50, 10, 400, 24, 24, (char*)"IMX6U-ALPHA TOUCH SCREEN TEST");
lcd_show_string(50, 40, 200, 16, 16, (char*)"TOUCH SCREEN TEST");
lcd_show_string(50, 60, 200, 16, 16, (char*)"ATOM@ALIENTEK");
lcd_show_string(50, 80, 200, 16, 16, (char*)"2019/3/27");
lcd_show_string(50, 110, 400, 16, 16, (char*)"TP Num :");
lcd_show_string(50, 130, 200, 16, 16, (char*)"Point0 X:");
lcd_show_string(50, 150, 200, 16, 16, (char*)"Point0 Y:");
lcd_show_string(50, 170, 200, 16, 16, (char*)"Point1 X:");
lcd_show_string(50, 190, 200, 16, 16, (char*)"Point1 Y:");
lcd_show_string(50, 210, 200, 16, 16, (char*)"Point2 X:");
lcd_show_string(50, 230, 200, 16, 16, (char*)"Point2 Y:");
lcd_show_string(50, 250, 200, 16, 16, (char*)"Point3 X:");
lcd_show_string(50, 270, 200, 16, 16, (char*)"Point3 Y:");
lcd_show_string(50, 290, 200, 16, 16, (char*)"Point4 X:");
lcd_show_string(50, 310, 200, 16, 16, (char*)"Point4 Y:");
while(1)
{
/* 触摸中断函数: gt9147_irqhandler() , 选择是否显示坐标数据 */
delayms(10);
i++;
if(i == 50)
{
i = 0;
state = !state;
led_switch(LED0,state);
}
}
return 0;
}bsp_lcd.h 文件 ，画点函数 代码参考 ->
#ifndef _BSP_LCD_H
#define _BSP_LCD_H
#include "imx6ul.h"
/* 颜色 */
#define LCD_BLUE 0x000000FF
#define LCD_GREEN 0x0000FF00
#define LCD_RED 0x00FF0000
#define LCD_CYAN 0x0000FFFF
#define LCD_MAGENTA 0x00FF00FF
#define LCD_YELLOW 0x00FFFF00
#define LCD_LIGHTBLUE 0x008080FF
#define LCD_LIGHTGREEN 0x0080FF80
#define LCD_LIGHTRED 0x00FF8080
#define LCD_LIGHTCYAN 0x0080FFFF
#define LCD_LIGHTMAGENTA 0x00FF80FF
#define LCD_LIGHTYELLOW 0x00FFFF80
#define LCD_DARKBLUE 0x00000080
#define LCD_DARKGREEN 0x00008000
#define LCD_DARKRED 0x00800000
#define LCD_DARKCYAN 0x00008080
#define LCD_DARKMAGENTA 0x00800080
#define LCD_DARKYELLOW 0x00808000
#define LCD_WHITE 0x00FFFFFF
#define LCD_LIGHTGRAY 0x00D3D3D3
#define LCD_GRAY 0x00808080
#define LCD_DARKGRAY 0x00404040
#define LCD_BLACK 0x00000000
#define LCD_BROWN 0x00A52A2A
#define LCD_ORANGE 0x00FFA500
#define LCD_TRANSPARENT 0x00000000
/* 屏幕ID */
#define ATK4342 0X4342 /* 4.3寸480*272 */
#define ATK4384 0X4384 /* 4.3寸800*480 */
#define ATK7084 0X7084 /* 7寸800*480 */
#define ATK7016 0X7016 /* 7寸1024*600 */
#define ATK1018 0X1018 /* 10.1寸1280*800 */
#define ATKVGA 0xff00 /* VGA */
/* LCD显存地址 */
#define LCD_FRAMEBUF_ADDR (0x89000000)
/* LCD控制参数结构体 */
struct tftlcd_typedef{
unsigned short height; /* LCD屏幕高度 */
unsigned short width; /* LCD屏幕宽度 */
unsigned char pixsize; /* LCD每个像素所占字节大小 */
unsigned short vspw;
unsigned short vbpd;
unsigned short vfpd;
unsigned short hspw;
unsigned short hbpd;
unsigned short hfpd;
unsigned int framebuffer; /* LCD显存首地址 */
unsigned int forecolor; /* 前景色 */
unsigned int backcolor; /* 背景色 */
unsigned int id; /* 屏幕ID */
};
extern struct tftlcd_typedef tftlcd_dev;
/* 函数声明 */
void lcd_init(void);
unsigned short lcd_read_panelid(void);
void lcdgpio_init(void);
void lcdclk_init(unsigned char loopDiv, unsigned char prediv, unsigned char div);
void lcd_reset(void);
void lcd_noreset(void);
void lcd_enable(void);
//void video_pllinit(unsigned char loopdivi, unsigned char postdivi);
void lcd_clear(unsigned int color);
void lcd_fill(unsigned short x0, unsigned short y0, unsigned short x1, unsigned short y1, unsigned int color);
/*
* @description : 画点函数
* @param - x : x轴坐标
* @param - y : y轴坐标
* @param - color : 颜色值
* @return : 无
*/
static inline void lcd_drawpoint(unsigned short x,unsigned short y,unsigned int color)
{
*(unsigned int*)((unsigned int)tftlcd_dev.framebuffer +
tftlcd_dev.pixsize * (tftlcd_dev.width * y+x))=color;
}
/*
* @description : 读取指定点的颜色值
* @param - x : x轴坐标
* @param - y : y轴坐标
* @return : 读取到的指定点的颜色值
*/
static inline unsigned int lcd_readpoint(unsigned short x,unsigned short y)
{
return *(unsigned int*)((unsigned int)tftlcd_dev.framebuffer +
tftlcd_dev.pixsize * (tftlcd_dev.width * y + x));
}
static inline void lcd_draw_big_point(unsigned short x,unsigned short y,unsigned int color)
{
// 画一个5x5的点阵
lcd_drawpoint(x, y, color);
lcd_drawpoint(x+1, y, color);
lcd_drawpoint(x-1, y, color);
lcd_drawpoint(x, y+1, color);
lcd_drawpoint(x, y-1, color);
lcd_drawpoint(x+1, y+1, color);
lcd_drawpoint(x-1, y+1, color);
lcd_drawpoint(x+1, y-1, color);
lcd_drawpoint(x-1, y-1, color);
}
/*
内联函数要放在头文件中的原因：编译器需要看到完整定义,每个编译单元需要自己的副本。
inline 关键字：建议编译器将函数内联展开，而不是进行函数调用。减少函数调用开销（压栈、跳转、返回等）。
函数内联展开和普通函数调用在性能上有显著差异。
何时使用 static inline:
1、函数很小（1-5行代码，画点函数 只是一行内存访问）
2、频繁调用（减少调用开销，每个像素点都可能调用）
3、性能关键（避免函数调用延迟，图形操作需要快速）
4、通用工具函数（多个文件都需要）
画一个800×480的屏幕：
函数调用：800×480 = 384,000次函数调用
内联：384,000次直接内存写入
假设每次函数调用需要10个时钟周期：
函数调用总开销：384,000 × 10 = 3,840,000 周期
在100MHz的MCU上：约38.4ms的纯调用开销
内联可以节省这38.4ms！
*/
#endif