unsigned char Ad_Read(unsigned char address)
{
	unsigned char temp=0;
	IIC_Start();
	IIC_SendByte(0x90);//0x90-写
	IIC_WaitAck();
	IIC_SendByte(address);
	IIC_WaitAck();
	IIC_Start();
	IIC_SendByte(0x91);//0x91-读
	IIC_WaitAck();
	temp = IIC_RecByte();
	IIC_SendAck(1);//发送非应答信号 
	IIC_Stop();
	return temp;
}

void Da_Write(unsigned char dat)
{
	IIC_Start();
	IIC_SendByte(0x90);//0x90-写
	IIC_WaitAck();
	IIC_SendByte(0x41);//bit6 需置1才能开启DAC
	IIC_WaitAck();
	IIC_SendByte(dat);
	IIC_WaitAck();
	IIC_Stop();
}