i2csample.c

一个用GPIO实现I2C接口进行数据通讯的例子

/******************************************************************************************
*              Functions
*******************************************************************************************/
void i2c_init(void)
{
	unsigned int value;

	value =	TLG1100_SDA| TLG1100_SCL /* | BUSENABLE*/;
	*(volatile unsigned int *)(BASE_GPIO_TIMER+GPIO_DIR) |= value;
	*(volatile unsigned int *)(BASE_GPIO_TIMER+GPIO_OUT) |= value;
}

static void i2c_delay(unsigned int time)
{
	while(time--) 
	{	
        ;
	}
}
static void set_i2c_pin_dir(unsigned char Dir)
{
	if(Dir == TLG_IIC_OUTPUT)
	{
		//set pin as output
	}
	else
	{
		//set pin as input
	}
}
static void set_i2c_pin(unsigned int pin)
{
	 // set pin high 
	 //*(volatile unsigned int *)(BASE_GPIO_TIMER+GPIO_OUT) |= pin;
}
static void clr_i2c_pin(unsigned int pin)
{
	// set pin low
	*(volatile unsigned int  *)(BASE_GPIO_TIMER+GPIO_OUT) &= (~pin);
}

static unsigned char get_i2c_pin(unsigned int pin)
{
	unsigned char ret;
	unsigned int value;

	//read gpio
	value =	*(volatile unsigned int *)(BASE_GPIO_TIMER+GPIO_IN);
	if ((value & pin) == 0)
		ret	= 0;
	else
		ret	= 1;

	return ret;
}

static void i2c_begin(void)
{
	set_i2c_pin_dir(TLG_IIC_OUTPUT);//set gpio for output
	
	i2c_delay(I2C_DELAY_UNIT << 0);
	set_i2c_pin(TLG1100_SDA);	
	i2c_delay(I2C_DELAY_UNIT << 0);
	set_i2c_pin(TLG1100_SCL);
	i2c_delay(I2C_DELAY_UNIT << 0);
	clr_i2c_pin(TLG1100_SDA);	
	i2c_delay(I2C_DELAY_UNIT << 0);
	clr_i2c_pin(TLG1100_SCL);
	i2c_delay(I2C_DELAY_UNIT << 0);
}

static void i2c_end(void)
{
	set_i2c_pin_dir(TLG_IIC_OUTPUT);//set gpio for output
	
	i2c_delay(I2C_DELAY_UNIT << 2);
	clr_i2c_pin(TLG1100_SDA);
	i2c_delay(I2C_DELAY_UNIT << 2);
	set_i2c_pin(TLG1100_SCL);
	i2c_delay(I2C_DELAY_UNIT << 3);
	set_i2c_pin(TLG1100_SDA);
	i2c_delay(I2C_DELAY_UNIT << 4);
}

static void i2c_write_ask(unsigned char flag)
{
	set_i2c_pin_dir(TLG_IIC_OUTPUT);//set gpio for output
	
	if(flag)
		set_i2c_pin(TLG1100_SDA);
	else
		clr_i2c_pin(TLG1100_SDA);
	i2c_delay(I2C_DELAY_UNIT << 0);
	set_i2c_pin(TLG1100_SCL);
	i2c_delay(I2C_DELAY_UNIT << 0);
	clr_i2c_pin(TLG1100_SCL);
	i2c_delay(I2C_DELAY_UNIT << 0);

}


static unsigned char i2c_read_ack(void)
{	
	unsigned char ret;
	
	set_i2c_pin_dir(TLG_IIC_INPUT);//set gpio for input
	
	i2c_delay(I2C_DELAY_UNIT << 0);
	set_i2c_pin(TLG1100_SCL);
	i2c_delay(I2C_DELAY_UNIT << 0);
	if (!get_i2c_pin(TLG1100_SDA))
	{
		ret = 1;
	}
	else
	{
		ret = 0;
	}

	i2c_delay(I2C_DELAY_UNIT << 0);
	clr_i2c_pin(TLG1100_SCL);
       i2c_delay(I2C_DELAY_UNIT << 0);	

	return ret;
}

static unsigned char i2c_read_byte(void)
{
	unsigned char i;
	unsigned char ret;

	ret	= 0;
	
	set_i2c_pin_dir(TLG_IIC_INPUT);//set gpio for input
	
	
	for	(i=0; i<8; i++)
	{			
		i2c_delay(I2C_DELAY_UNIT << 0);
		set_i2c_pin(TLG1100_SCL);	
		i2c_delay(I2C_DELAY_UNIT << 0);
		ret	= ret<<1;
		if (get_i2c_pin(TLG1100_SDA))
			ret |= 1;
		i2c_delay(I2C_DELAY_UNIT << 0);
		clr_i2c_pin(TLG1100_SCL);
	}		

	return ret;
}

static unsigned char i2c_write_byte(unsigned char data)
{
	unsigned char i;
	
	set_i2c_pin_dir(TLG_IIC_OUTPUT);//set gpio for output
	
	for	(i=0; i<8; i++)
	{
		i2c_delay(I2C_DELAY_UNIT << 0);
		if (data & 0x80)
			set_i2c_pin(TLG1100_SDA);
		else
			clr_i2c_pin(TLG1100_SDA);
		data <<= 1;

		i2c_delay(I2C_DELAY_UNIT << 0);
		set_i2c_pin(TLG1100_SCL);
		i2c_delay(I2C_DELAY_UNIT << 0);
		clr_i2c_pin(TLG1100_SCL);		
	}	
	return i2c_read_ack();
}





/***************************************************************************
*
*
*    IIC Write data for Tlg1100
*                                    dab:device Id =0x2c
*                                    rab: register address
*                                    data: dump into register
*
****************************************************************************/
unsigned char I2C_WriteReg(unsigned char dab, unsigned short rab, unsigned short data)
{
	unsigned char tmpData = 0;

	i2c_begin();
	if (!i2c_write_byte(dab<<1))
	{
		i2c_end();
		return 0;
	}
	/* write 16bits register */
      tmpData = ((rab & 0x7f00) >> 8);

	if (!i2c_write_byte(tmpData))
	{
		i2c_end();
		return 0;
	}

	tmpData = (rab & 0x00ff);
	if (!i2c_write_byte(tmpData))
	{
		i2c_end();
		return 0;
	}
    /* write 16bits data */
	tmpData = ((data& 0xff00) >> 8);
	if (!i2c_write_byte(tmpData))
	{
		i2c_end();
		return 0;
	}
	
	tmpData = ((data) & 0x00ff);
	if (!i2c_write_byte(tmpData))
	{
		i2c_end();
		return 0;
	}


	i2c_end();
	return 1;
}