#include "reg51.h"
#include "intrins.h"
#define NOP() { _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); } 


sbit SPI45D081_CS =P1^5;//片選接口
sbit SPI45D081_SK =P1^6;//時鐘接口
sbit SPI45D081_DI =P1^7;//數據輸入接口
sbit SPI45D081_DO =P1^4;//數據輸出接口

delay(unsigned int t)
{
while(t--);
}

// SPI_SK上升沿數據有效 _/-
SPI45D081_WriteBits(unsigned char byte,unsigned char num_of_bits)
{
unsigned char count;
byte=byte<<(8-num_of_bits);
for(count=0;count<num_of_bits;count++)
{ SPI45D081_SK=0;
byte<<=1;
NOP();
SPI45D081_DI=CY;
NOP();
SPI45D081_SK=1;
NOP();
}
}
// SPI_SK下降沿數據有效 -\_
unsigned char SPI45D081_ReadByte()
{
unsigned char count,byte;
for(count=0;count<8;count++)
{ SPI45D081_SK=1;
NOP();
byte<<=1;
SPI45D081_SK=0;
NOP();
if(SPI45D081_DO) byte++;
NOP();
}
return(byte);
}
//Main Memory Page to Buffer 1 Transfer
void PageToBuffer1(unsigned int page)
{
SPI45D081_SK=1; //?? start
NOP();
SPI45D081_CS=0; //start
NOP();
//send 8 bit opcode, Main Memory Page to Buffer 1 Transfer: 0x53
SPI45D081_WriteBits(0x53,8);// fill 3 sk,don't care.
SPI45D081_WriteBits(0x00,3);//send 12 bit address to 45D081
SPI45D081_WriteBits( (unsigned char)(page>>8) , 4 );
SPI45D081_WriteBits( (unsigned char)(page) , 8 );
// fill 9 sk,don't care.
SPI45D081_WriteBits( 0x00 , 4 );
SPI45D081_WriteBits( 0x00 , 5 );//total 32 bit
SPI45D081_CS=1; // end
delay(200);}//
unsigned char ReadDataFromBuffer1(unsigned int address)
{
unsigned char dat; 
SPI45D081_SK=1; //?? start
NOP();
SPI45D081_CS=0; //start
NOP();
//send 8 bit opcode:0x54
SPI45D081_WriteBits(0x54,8);// fill 15 sk,don't care.
SPI45D081_WriteBits(0x00,8);
SPI45D081_WriteBits(0x00,7);//send 9 bit address to 45D081 buffer1
SPI45D081_WriteBits( (unsigned char)(address>>8) , 1 );
SPI45D081_WriteBits( (unsigned char)(address) , 8 );//fill 8 bits blank
SPI45D081_WriteBits( 0x00 , 8 );// receive data
dat=SPI45D081_ReadByte() ;
SPI45D081_CS=1; // end
return(dat);
}
//注：該程序適用程度可靠，注意使用的方法和硬件連接方式