#include "spi_slave.h"
sbit c51_SDO = 0x94;
sbit c51_SDI = 0x92;
sbit c51_CS =0x93;
sbit c51_CLK =0x90;
unsigned char SpiSlave(unsigned char* sendData)
{
unsigned char trigReady;
unsigned char bitCount;
unsigned char dataBuff;
unsigned char tranState=0;
for(;;)
{
if (c51_CS)
{
tranState=0;
bitCount=0;
dataBuff=0;
}
else
switch (tranState)
{
case 0:
{
if (c51_CS==0)
{
tranState=1;
c51_SDO=1;
c51_SDI=1;
c51_CLK=1;
}
break;
}
case 1:
{
if (c51_CLK==0) trigReady=1;
if (c51_CLK==1 && trigReady==1)
{
dataBuff<<=1;
if (c51_SDI==1)
{
dataBuff|=0x01;
}
if (bitCount==7)
{
tranState=2;
c51_SDO=0;
}
bitCount++;
trigReady=0;
}
break;
}
case 2:
{
if (c51_CLK==0) trigReady=1;
if (c51_CLK==1 && trigReady==1)
{
tranState=3;
}
break;
}
case 3:
{
if (c51_CLK==0)
{
c51_SDO=1;
bitCount=0;
if(dataBuff==0x61)//send data
{
dataBuff=*sendData;
tranState=4;
}
else//receive data
{
tranState=5;
}
}
break;
}
case 4:
{
if (c51_CLK==1) trigReady=1;
if ((c51_CLK==0) && (trigReady==1))
{
trigReady=0;
bitCount++;
if (bitCount >= 9) return 0;
if ((dataBuff&0x80)==0)
c51_SDO=0;
else
c51_SDO=1;
dataBuff<<=1;
}
break;
}
case 5:
{
if (bitCount>=8)
{
*sendData=dataBuff;
return 1;
}
if (c51_CLK==0) trigReady=1;
if ((c51_CLK==1) && (trigReady==1))
{
trigReady=0;
dataBuff<<=1;
if (c51_SDI==1)
dataBuff|=0x01;
bitCount++;
}
break;
}
}
}
}
