出现的问题是：一只手指按下没反应；两只手指按下，只有一只手指是有反应的；
三只手指按下，只有两只手指有反应，这是为何？

代码如下：
[mw_shl_code=c,true]#include "sys.h" #include "delay.h" #include "led.h" #include "usart.h" #include "lcd.h" #include "beep.h" #include "touch.h" /* 本实验的目的是： 通过触摸屏实现一个手写的功能； */ /* 1.现象： 两只手按下时，只有一只手有反应； 三只手按下时，只有两只手有反应； 四只手按下时，只有三只手有反应，为何？ 2.加上if（）语句的判断，则全然不行，思考为什么？ */ int main(void){ u32 i; u16 x ; u16 y; u8 buf[16] = {0}; Stm32_Clock_Init(336,8,2,7);//设置时钟,168MHZ delay_init(168); //初始化延时函数 LED_Init(); uart_init(84-1,115200); lcd_init(); Touch_Init(); LCD_Reg = 0X2C00; for(i=0;i<799*479;i++){ LCD_Ram = 0Xffff; } while(1){ //在这里采用轮询方式 Read_Reg(0x814e,buf,1); if(buf[0]&0x80){ //若有数据收到，则获取坐标，然后在LCD上描点；[/mw_shl_code] [mw_shl_code=c,true] switch(buf[0]&0xf){ case 1: Read_Reg(0x8158,buf,4); x = buf[0] | (buf[1]<<8); y = buf[2] | (buf[3]<<8); Big_Point_Color(x,y,0xf800); break; case 2: Read_Reg(0x8158,buf,4); x = buf[0] | (buf[1]<<8); y = buf[2] | (buf[3]<<8); Big_Point_Color(x,y,0xf800); Read_Reg(0x8160,buf,4); x = buf[0] | (buf[1]<<8); y = buf[2] | (buf[3]<<8); Big_Point_Color(x,y,0xf800); break; case 3: Read_Reg(0x8158,buf,4); x = buf[0] | (buf[1]<<8); y = buf[2] | (buf[3]<<8); Big_Point_Color(x,y,0xf800); Read_Reg(0x8160,buf,4); x = buf[0] | (buf[1]<<8); y = buf[2] | (buf[3]<<8); Big_Point_Color(x,y,0xf800); Read_Reg(0x8158,buf,4); x = buf[0] | (buf[1]<<8); y = buf[2] | (buf[3]<<8); Big_Point_Color(x,y,0xf800); Read_Reg(0x8168,buf,4); x = buf[0] | (buf[1]<<8); y = buf[2] | (buf[3]<<8); Big_Point_Color(x,y,0xf800); break; case 4: Read_Reg(0x8158,buf,4); x = buf[0] | (buf[1]<<8); y = buf[2] | (buf[3]<<8); Big_Point_Color(x,y,0xf800); Read_Reg(0x8160,buf,4); x = buf[0] | (buf[1]<<8); y = buf[2] | (buf[3]<<8); Big_Point_Color(x,y,0xf800); Read_Reg(0x8168,buf,4); x = buf[0] | (buf[1]<<8); y = buf[2] | (buf[3]<<8); Big_Point_Color(x,y,0xf800); Read_Reg(0x8170,buf,4); x = buf[0] | (buf[1]<<8); y = buf[2] | (buf[3]<<8); Big_Point_Color(x,y,0xf800); break; case 5: Read_Reg(0x8158,buf,4); x = buf[0] | (buf[1]<<8); y = buf[2] | (buf[3]<<8); Big_Point_Color(x,y,0xf800); Read_Reg(0x8160,buf,4); x = buf[0] | (buf[1]<<8); y = buf[2] | (buf[3]<<8); Big_Point_Color(x,y,0xf800); Read_Reg(0x8168,buf,4); x = buf[0] | (buf[1]<<8); y = buf[2] | (buf[3]<<8); Big_Point_Color(x,y,0xf800); Read_Reg(0x8170,buf,4); x = buf[0] | (buf[1]<<8); y = buf[2] | (buf[3]<<8); Big_Point_Color(x,y,0xf800); Read_Reg(0x8178,buf,4); x = buf[0] | (buf[1]<<8); y = buf[2] | (buf[3]<<8); Big_Point_Color(x,y,0xf800); break; } buf[0] &=0x7f ;//清标志； Write_Reg(0x814e,buf,1); } } } [/mw_shl_code]