/************从SD2200发送一个字节*************/
void I2CSendByte(uchar demand,bit order) //order=1,H_L;order=0,L_H
{
uchar i=8; //order=1，从HI-->LO发送8bit数据
//order=0，从LO-->HI发送8bit数据
if(order)
{
while(i--)
{
SCL=0;
_nop_();
SDA=(bit)(demand&0x80);
demand<<=1;
I2CWait();
SCL=1;
I2CWait();
}
SCL=0;
}
else
{
while(i--)
{
SCL=0;
_nop_();
SDA=(bit)(demand&0x01);
demand>>=1;
I2CWait();
SCL=1;
I2CWait();
}
SCL=0;
}
}
/*********发送 ACK*********/
void I2CAck(void)
{
SDA=0;
SCL=0;
I2CWait();
SCL=1;
I2CWait();
SCL=0;
}
/*********发送NO ACK*********/
void I2CNoAck(void)
{
SDA=1;
SCL=0;
I2CWait();
SCL=1;
I2CWait();
SCL=0;
}
/********关闭SD2200的I2C总线*******/
void I2CStop(void)
{
SDA=0;
SCL=0;
I2CWait();
SCL=1;
I2CWait();
SDA=1;
}
/********开启SD2200的I2C总线********/
bit I2CStart(void)
{
SDA=1;
SCL=1;
I2CWait();
if(!SDA)return 0;//SDA线为低电平则总线忙,退出
SDA=0;
I2CWait();
while(SDA)return 0;//SDA线为高电平则总线出错,退出
SCL=0;
I2CWait();
return 1;
}
/*********读取ACK信号*********/
bit I2CWaitAck(void) //返回为:1=有ACK,0=无ACK
{
uchar errtime=255;
SCL=0;
SDA=1;
I2CWait();
SCL=1;
I2CWait();
while(SDA)
{
errtime--;
if(!errtime)
SCL=0;
return 0;
}
SCL=0;
return 1;
}
/*
Function: I2CRead
Return: 8-bit data read from I2C bus
Arguments:
Description: read 8-bit data from I2C bus
*/
unsigned char I2CRead(void)
{
unsigned char temp;
/* Reception works if transfer is initiated in read mode */
RCEN = 1; /* Enable data reception */
while(!BF); /* wait for buffer full */
temp = SSPBUF; /* Read serial buffer and store in temp register */
I2CWait(); /* wait to check any pending transfer */
return temp; /* Return the read data from bus */
}
/*********MCU从SD2200读入一字节*********/
uchar I2CReceiveByte(void)
{
uchar i=8;
uchar ddata=0;
SDA=1;
while(i--)
{
ddata>>=1; //数据从低位开始读取
SCL=0;
I2CWait();
SCL=1;
I2CWait(); //从低位开始 ddata|=SDA;ddata>>=1
if(SDA)
{
ddata|=0x80;
}
}
SCL=0;
return ddata;
}
/*
Function: I2CSend
Return:
Arguments: dat - 8-bit data to be sent on bus
data can be either address/data byte
Description: Send 8-bit data on I2C bus
*/
void I2CSend(unsigned char dat)
{
SSPBUF = dat; /* Move data to SSPBUF */
while(BF); /* wait till complete data is sent from buffer */
I2CWait(); /* wait for any pending transfer */
}
