i2c.c

DDS 单片机控制AD7008 产生正弦波

#include "I2C.h"

unsigned char data I2C_Delay_t;
#define I2C_Delay()\
{\
	I2C_Delay_t = (I2C_DELAY_VALUE);\
	while ( --I2C_Delay_t != 0 );\
}
void I2C_Init()
{
	I2C_SCL = 1;
	I2C_Delay();
	I2C_SDA = 1;
	I2C_Delay();
}
void I2C_Start()
{
	I2C_SDA = 1;
	I2C_Delay();
	I2C_SCL = 1;
	I2C_Delay();
	I2C_SDA = 0;
	I2C_Delay();
	I2C_SCL = 0;
	I2C_Delay();
}
char I2C_Read()
{
	char dat;
	unsigned char t = 8;
	I2C_SDA = 1;	//在读取数据之前，要把SDA拉高
	do
	{
		I2C_SCL = 1;
		I2C_Delay();
		dat <<= 1;
		if ( I2C_SDA ) dat |= 0x01;
		I2C_SCL = 0;
		I2C_Delay();
	} while ( --t != 0 );
	return dat;
}
void I2C_Write(char dat)
{
	unsigned char t = 8;
	do
	{
		I2C_SDA = (bit)(dat & 0x80);
		dat <<= 1;
		I2C_SCL = 1;
		I2C_Delay();
		I2C_SCL = 0;
		I2C_Delay();
	} while ( --t != 0 );
}
bit I2C_GetAck()
{
	bit ack;
	I2C_SDA = 1;
	I2C_Delay();
	I2C_SCL = 1;
	I2C_Delay();
	ack = I2C_SDA;
	I2C_SCL = 0;
	I2C_Delay();
	return ack;
}
void I2C_PutAck(bit ack)
{
	I2C_SDA = ack;
	I2C_Delay();
	I2C_SCL = 1;
	I2C_Delay();
	I2C_SCL = 0;
	I2C_Delay();
}
void I2C_Stop()
{
	unsigned int t = I2C_STOP_WAIT_VALUE;
	I2C_SDA = 0;
	I2C_Delay();
	I2C_SCL = 1;
	I2C_Delay();
	I2C_SDA = 1;
	I2C_Delay();
	while ( --t != 0 );		//在下一次产生Start之前，要加一定的延时
}

bit I2C_Gets
(
	unsigned char SlaveAddr,
	unsigned int SubAddr,
	unsigned char SubMod,
	char *dat,
	unsigned int Size
)
{
	unsigned char i;
	char a[3];
	if ( Size == 0 ) return 0;
	a[0] = (SlaveAddr << 1);
	if ( SubMod > 2 ) SubMod = 2;
	if ( SubMod != 0 )
	{
		if ( SubMod == 1 )
		{
			a[1] = (char)(SubAddr);
		}
		else
		{
			a[1] = (char)(SubAddr >> 8);
			a[2] = (char)(SubAddr);
		}
		SubMod++;
		I2C_Start();
		for ( i=0; i<SubMod; i++ )
		{
			I2C_Write(a[i]);
			if ( I2C_GetAck() )
			{
				I2C_Stop();
				return 1;
			}
		}
	}
	I2C_Start();
	I2C_Write(a[0]+1);
	if ( I2C_GetAck() )
	{
		I2C_Stop();
		return 1;
	}

	for (;;)
	{
		*dat++ = I2C_Read();
		if ( --Size == 0 )
		{
			I2C_PutAck(1);
			break;
		}
		I2C_PutAck(0);
	}
	I2C_Stop();
	return 0;
}