//PPM 解码程序
//用INT0接PPM信号
//T0计数，用来测量脉宽
//注意，这个不是标准的PPM信号，刚好和PPM信号相位相反
//测得的PPM信号在LCD上显示
//PPM信号取自天地飞6A接收机
//时间：2012年2月15日0:22:31
# include <stc.h>
# include <intrins.h>

# define DataPort P0

sbit RS=P2^4;
sbit RW=P2^5;
sbit EN=P2^6;

unsigned char channel=0,i=0;
unsigned int xdata PPM_channel1[10],PPM_channel2[10],PPM_channel3[10],PPM_channel4[10],PPM_channel5[10],PPM_channel6[10];
bit Timer0_OverFlowFlag=0;//定时器0的溢出标志，如果溢出，则有问题；
unsigned char qian,bai,shi,ge;

# define RS_CLR RS=0;
# define RS_SET RS=1;
# define RW_SET RW=1;
# define RW_CLR RW=0;
# define EN_CLR	EN=0;
# define EN_SET EN=1;

//和ＬＣＤ显示有关的函数定义
void LCD_Check_Busy(void); //查忙函数
void LCD_Clear(void);//清屏函数
void LCD_Init(void);//lcd初始化函数
void LCD_Write_Com(unsigned char com);//控制字写入函数
void LCD_Write_Data(unsigned char Data);//数据写入函数
void LCD_Write_Char(unsigned char x,unsigned char y,unsigned char Data);//写入单个字符
void LCD_Write_String(unsigned char x,unsigned char y,unsigned char *s);//写入字符串
unsigned int filter(unsigned int *s);//中值平局滤波； 
void DepartNum(unsigned int temp);//用于分解要显示的数据

void DelayUs2x(unsigned char t);
void DelayMs(unsigned int t);


void main(void)
{  	
    unsigned char *InitIform;
	unsigned int temp;
	InitIform="Init_is_OK";
	LCD_Init();
	DelayMs(10);
	LCD_Write_String(3,0,InitIform);


//初始化Timer0
	TMOD=0x01;//timer0 方式1
	ET0=1;//允许timer0中断

//初始化INT0
	IT0=1;//负跳变触发中断；
	EX0=1;

	EA=1;
	
	DelayMs(10000);
	while(1)
	{
	    temp=filter(PPM_channel1);
		DepartNum(temp);
		LCD_Write_Char(0,0,'A');
		LCD_Write_Char(1,0,qian);
		LCD_Write_Char(2,0,bai);
		LCD_Write_Char(3,0,shi);
		LCD_Write_Char(4,0,ge);

	    temp=filter(PPM_channel2); 		
		DepartNum(temp);
		LCD_Write_Char(5,0,'B');
		LCD_Write_Char(6,0,qian);
		LCD_Write_Char(7,0,bai);
		LCD_Write_Char(8,0,shi);
		LCD_Write_Char(9,0,ge);

	    temp=filter(PPM_channel3);
		DepartNum(temp);
		LCD_Write_Char(10,0,'C');
		LCD_Write_Char(11,0,qian);
		LCD_Write_Char(12,0,bai);
		LCD_Write_Char(13,0,shi);
		LCD_Write_Char(14,0,ge);

	    temp=filter(PPM_channel4);
		DepartNum(temp);
		LCD_Write_Char(0,1,'D');
		LCD_Write_Char(1,1,qian);
		LCD_Write_Char(2,1,bai);
		LCD_Write_Char(3,1,shi);
		LCD_Write_Char(4,1,ge);
		
	    temp=filter(PPM_channel5);
		DepartNum(temp);
		LCD_Write_Char(5,1,'E');
		LCD_Write_Char(6,1,qian);
		LCD_Write_Char(7,1,bai);
		LCD_Write_Char(8,1,shi);
		LCD_Write_Char(9,1,ge);

	    temp=filter(PPM_channel6);
		DepartNum(temp);
		LCD_Write_Char(10,1,'F');
		LCD_Write_Char(11,1,qian);
		LCD_Write_Char(12,1,bai);
		LCD_Write_Char(13,1,shi);
		LCD_Write_Char(14,1,ge);

//		DelayMs(1000);
	}
					  
}


void DelayUs2x(unsigned char t)
{   
 while(--t);
}

void DelayMs(unsigned int t)
{
     
 while(t--)
 {
     //大致延时1mS
     DelayUs2x(245);
	 DelayUs2x(245);
 }
}

//查忙函数
 void LCD_Check_Busy(void) 
 { 
 unsigned char i=255;
 DataPort= 0xff; 
 RS_CLR; 
 RW_SET; 
 EN_SET; 
 while(i--&&(DataPort&0x80));
 EN_CLR;
 }

//控制字写入函数，入口参数是控制字
void LCD_Write_Com(unsigned char com)
{
	LCD_Check_Busy();
	RS_CLR;
	RW_CLR;
	DataPort=com;
	EN_SET;
	_nop_();
	EN_CLR;
}

//写入数据，入口参数是要写入的数据
void LCD_Write_Data(unsigned char Data)
{
	LCD_Check_Busy();
	RS_SET;
	RW_CLR;
	DataPort=Data;
	EN_SET;
	_nop_();
	EN_CLR;	
}

//清屏函数
void LCD_Clear(void )
{
	LCD_Write_Com(0x01);
	DelayMs(5);		
}

//LCD显示字符串，入口参数是 字符显示的位置X（0-15），显示的行数y（0,1 ），*S显示的字符串
void LCD_Write_String(unsigned char x,unsigned char y, unsigned char *s)
{
	if(y==0) LCD_Write_Com(0x80+x);
	else LCD_Write_Com(0xc0+x);
	while(*s)
	{
		LCD_Write_Data(*s);
		s++;
	}
}

//LCD显示字符串，入口参数是 字符显示的位置X（0-15），显示的行数y（0,1 ），Data显示的字符
void LCD_Write_Char(unsigned char x,unsigned char y,unsigned char Data)
{
	 if(y==0) LCD_Write_Com(0x80+x);
	 else LCD_Write_Com(0xc0+x);
   	 DelayMs(1);//a little delay for simulation
	 LCD_Write_Data(Data);
}


//lcd初始化函数
void LCD_Init(void)
{
	LCD_Write_Com(0x38);// set the display model
	DelayMs(5);
	LCD_Write_Com(0x08);//turn down the display
	//LCD_Write_Com(0x01);//clear the display
	LCD_Clear();
	LCD_Write_Com(0x06);//set the 光标 moving model
	DelayMs(5);
	LCD_Write_Com(0x0c);//显示开和光标设置
}

/****************************************
用于显示的数位分解函数，把数据转化为ASCII码
入口参数是要显示的数据
****************************************/
void DepartNum(unsigned int temp)
{
	qian=temp/1000+0x30;
	bai=temp%1000/100+0x30;
	shi=temp%100/10+0x30;
	ge= temp%10+0x30;
}

void ISIR_INT0(void) interrupt 0
{
	unsigned int PPM_temp;
	if(TR0)
	{
		TR0=0;//停止计数；
		PPM_temp=TH0;
		PPM_temp=(PPM_temp<<8)|TL0;
		TH0=0;
		TL0=0;
		TR0=1;//给TH0和TL0赋初值后重新启动定时器
	}
	else
	{
		TH0=0;//如果是第一次启动中断，则启动timer0
		TL0=0;
		TR0=1;
	}
	if(PPM_temp>3000|| Timer0_OverFlowFlag)//判断引导区
	{
		channel=0;
		Timer0_OverFlowFlag=0;
		i++;
		if(i==10) i=0;
	}
	switch(channel)
	{
	case 1: PPM_channel1[i]=PPM_temp; break;
	case 2: PPM_channel2[i]=PPM_temp; break;
	case 3: PPM_channel3[i]=PPM_temp; break;
	case 4: PPM_channel4[i]=PPM_temp; break;
	case 5: PPM_channel5[i]=PPM_temp; break;
	case 6: PPM_channel6[i]=PPM_temp; break;
	case 7: break;
	case 8: break;
	default:break;
	}
	channel++;
}

void ISIR_Timer0(void) interrupt 1
{
	Timer0_OverFlowFlag=1;
}

unsigned int filter(unsigned int *s)
{
	unsigned char k,j;
	unsigned int sum=0;
	unsigned int temp;
	for(k=0;k<9;k++)
		for(j=k+1;j<10;j++)	   
		if(s[k]>s[j])
		{
			temp=s[k];
			s[k]=s[j];
			s[j]=temp;
		}
	for(k=1;k<9;k++)
	sum+=s[k];
	sum=sum/8;
	return sum;
}