spi.c

用于51系列单片机将普通串口变成模拟的spi口的程序

#include "SPI.h"

unsigned  char DATA_BUF;
#define DATA7	((DATA_BUF&BYTE_BIT7) != 0)
#define DATA0   ((DATA_BUF&BYTE_BIT0) != 0)
//sbit	flag	=DATA_BUF^7;	//考虑到某些不支持 sbit 类型
//sbit	flag1	=DATA_BUF^0;



//<附带主机指令的SPI写操作>
void SpiCmdWrite(unsigned char command,unsigned char WriteBuf[],unsigned char len)
{
	unsigned char i;					

	SPI_CSN=0;						// Spi enable for write a spi command
	SpiWrite(command);				// Write config command写放配置命令
	for (i=0;i<len;i++)	// Write configration words  写放配置字
	{
		SpiWrite(WriteBuf[i]);
	}
	SPI_CSN=1;						// Disable Spi
}

//<附带主机指令的SPI读操作>
void SpiCmdRead(unsigned char command,unsigned char ReadBuf[],unsigned char len)
{

	unsigned char i;
	SPI_CSN=0;						// Spi enable for write a spi command
	SpiWrite(command);				// Read payload command	
	for (i = 0 ;i < len ;i++)
	{
		ReadBuf[i]=SpiRead();		// Read data and save to buffer		
	}
	SPI_CSN=1;						// Disable spi

}


void SpiInit(void)
{
	SPI_MOSI_DDR = 1;
	SPI_MISO_DDR = 0;
	SPI_SCK_DDR  = 1;
	SPI_CSN_DDR  = 1;

	SPI_CSN=1;	// Spi 	disable	
	SPI_SCK=0;	// Spi clock line init low
}


unsigned char SpiRead(void)
{
	unsigned char i;
	for (i=0;i<8;i++)
	{
		DATA_BUF=DATA_BUF<<1;
		SPI_SCK=1;
		if (SPI_MISO)	//读取最高位，保存至最末尾，通过左移位完成整个字节
		{
			DATA_BUF|=BYTE_BIT0;
		}
		else
		{
			DATA_BUF&=~BYTE_BIT0;
		}
		SPI_SCK=0;
	 }
	 return DATA_BUF;
}

void SpiWrite(unsigned char send)
{
	unsigned char i;
	DATA_BUF=send;
	for (i=0;i<8;i++)
	{
		if (DATA7)	//总是发送最高位
		{
			SPI_MOSI=1;
		}
		else
		{
			SPI_MOSI=0;
		}
		SPI_SCK=1;
		DATA_BUF=DATA_BUF<<1;
		SPI_SCK=0;
	}
}