put9851.c

在8052下实现电平电压测试功能,自己开发的单片系统

/*
----------------------------------------------------------
;		(c) Copyright xami All Rights Reserved              
----------------------------------------------------------
;	SOURCE_FILE:    PUT9851.C
;	APPLICATION:	80c51\80c52
;	DESCRIPTION:    对ad9851写控制字
;	AUTHOR:         xami
;	DATE:           28 Apr. 2007
--------------------------------------------------------------------
<控制字转换公式>
f_OUT = (Phase * System_Clock)/(2^32)
--------------------------------------------------------------------
Phase			= 	decimal value of 32-bit frequency tuning word；
System_Clock	= 	direct input reference clock (in MHz) or 6′ the 
					input clock (in MHz) if the 6′ REFCLK Multiplier 
					is engaged；
f_OUT			=	frequency of the output signal in MHz.
--------------------------------------------------------------------
*/

 void input9851(unsigned long f_out)
{
uchar put_byte[4];							//存储频率控制字

unsigned long res;

res = (ulong)((float)f_out*204.8);			//频率转控制字


//生成控制字
put_byte[0]=0xff&res;
res=res>>8;
put_byte[1]=0xff&res;
res=res>>8;
put_byte[2]=0xff&res;
res=res>>8;
put_byte[3]=0xff&res;

//---------------------------------------------------------
//写adc9851控制字
//---------------------------------------------------------
P3_6= 1;		//W_CLK信号置低
P3_7= 1;		//FQ_UD信号置低

P2_5= 0;		//片选信号 开

P0= 0x00;			//第一个tuning word放到总线上
delay(2);			//3.5ns
P3_6= 0;			//W_CLK信号置高
delay(2);			//3.5ns
P3_6= 1;			//W_CLK信号置低

P0= put_byte[3];
delay(2);			//3.5ns
P3_6= 0;			//W_CLK信号置高
delay(2);			//3.5ns
P3_6= 1;			//W_CLK信号置低

P0= put_byte[2];
delay(2);			//3.5ns
P3_6= 0;			//W_CLK信号置高
delay(2);			//3.5ns
P3_6= 1;			//W_CLK信号置低

P0= put_byte[1];
delay(2);			//3.5ns
P3_6= 0;			//W_CLK信号置高
delay(2);			//3.5ns
P3_6= 1;			//W_CLK信号置低

P0= put_byte[0];
delay(2);			//3.5ns
P3_6= 0;			//W_CLK信号置高
delay(2);			//3.5ns
P3_6= 1;			//W_CLK信号置低

delay(3);			//4.5ns

P3_7= 0;		//FQ_UD信号置高
delay(6);		//7.5ns
P3_7= 1;		//FQ_UD信号置低，结束后7.5ns开始产生相应的频率

P2_5= 1;		//片选信号 关
//----------------------------------------------------------
}