i2c.c

此文档为采用FPGA实现的以太网MAC层

#include "i2c.h"




/* Initializes I2C Module */
void i2c_init(T_i2c *sti2c)
{
	/* Disable core and interrupts */
	sti2c->u16control = 0;

	/* Prescale to 10 - 50M/5*100K-1 = 100 = 0x64 */
	sti2c->u16prescale_h = 0;
	sti2c->u16prescale_l = 0x63;

	/* Enable core without interrupts */
	sti2c->u16control = 0x80;
}


/* Starts transfer with start bit and sends first byte, no stop bit sent */
/* Returns one if slave acknowledged */
Uint8 i2c_init_byte(T_i2c *sti2c, Uint8 addr,Uint8 mode)
{
	Uint8 x;

	/* Load tx reg with lsb cleared for wite op */
	sti2c->u16buf = (addr | mode) & 0xff;

	/* Set STA and WR */
	sti2c->u16cmdstat = i2c_cmd_sta | i2c_cmd_wr;


	/* Wait for tip to go low */
	while (1)
	{
		if ((sti2c->u16cmdstat & i2c_status_tip) == 0) break;
	}

	//while (sti2c->u16cmdstat & i2c_status_tip);


	//x = sti2c->u16cmdstat;
	x = sti2c->u16cmdstat;

	/* Transfer has completed, read ack status */
	if (x & i2c_status_rxack) return 0;
	return 1;

}

/* Sends byte after init condition has already occurred, waits for ack */
/* This is for the last byte which will terminate transfer */
Uint8 i2c_close_byte(T_i2c *sti2c, Uint8 val, Uint8 mode)
{
	Uint8 x;

	if (mode == i2c_mode_write)
	{
		sti2c->u16buf = val & 0xff;
	
		/* Set STO and WR */
		sti2c->u16cmdstat = i2c_cmd_sto | i2c_cmd_wr;
	}
	else if (mode == i2c_mode_read)
	{
		/* Set ack bit to be NACK  to terminate transfer */
		sti2c->u16cmdstat = i2c_cmd_sto | i2c_cmd_rd | i2c_cmd_ack;
	}

	/* Wait for tip to go low */
	while (sti2c->u16cmdstat & i2c_status_tip);

	if (mode == i2c_mode_write)
	{
		/* Transfer has completed, read ack status */
		if (sti2c->u16cmdstat & i2c_status_rxack) return 0;
		return 1;
	}
	else
	{
		/* Read back data */
		x = sti2c->u16buf & 0xff;
		return x;
	}
}

Uint8 i2c_mid_byte(T_i2c *sti2c, Uint8 val, Uint8 mode)
{
	Uint8 x;
	if (mode == i2c_mode_write)
	{
		sti2c->u16buf = val & 0xff;

		/* Set WR */
		sti2c->u16cmdstat = i2c_cmd_wr;
	}
	else
	{
		/* Set ack bit to be ACK to indicate another byte is requested */
		sti2c->u16cmdstat = i2c_cmd_rd;
	}

	/* Wait for tip to go low */
	while (sti2c->u16cmdstat & i2c_status_tip);

	if (mode == i2c_mode_write)
	{
		/* Transfer has completed, read ack status */
		if (sti2c->u16cmdstat & i2c_status_rxack) return 0;
		return 1;
	}
	else
	{
		/* Read back data */

		x = sti2c->u16buf & 0xff;
		return x;
	}
}

/********* User peripherals ***********/

Uint8 i2c_get_temp(T_i2c *psti2c)
{
	/* Set pointer */
	if (!i2c_init_byte(psti2c, I2C_TEMP_ADDR, i2c_mode_write)) return 0;
	/* Write to address 0 */
	if (!i2c_mid_byte(psti2c, 0, i2c_mode_write)) return 0;
	/* Initiation read request */
	if (!i2c_init_byte(psti2c, I2C_TEMP_ADDR, i2c_mode_read)) return 0;
	/* Read back single byte */
	return i2c_close_byte(psti2c, 0, i2c_mode_read);
}

/* Time should be in format:
Byte 0->Byte 2
<h> <m> <s>
*/
Uint32 rtc_timetoint(Uint8 h, Uint8 m, Uint8 s)
{
	return (Uint32) (h*3600 + m*60 + s);
}

/* Parse Uint32 value into hours, minutes and seconds */
void rtc_inttotime(Uint32 date_val, Uint8 *time_string)
{
	Uint32 tmplong;

	/* Reduce to only 24h of time */
	tmplong = date_val % (3600*24);

	/* Hours */
	time_string[0] = tmplong/3600;

	tmplong = tmplong % 3600;

	/* Minutes */
	time_string[1] = tmplong/60;

	/* Seconds */
	time_string[2] = tmplong % 60;

}

Uint8 i2c_rtc_settime(T_i2c *psti2c, Uint32 timeval)
{
	Uint8 tmp;

	if (!i2c_init_byte(psti2c, I2C_RTC_ADDR, i2c_mode_write)) return 0;
	if (!i2c_mid_byte(psti2c, 0, i2c_mode_write)) return 0;

	tmp = (Uint8) (timeval & 0xff);
	if (!i2c_mid_byte(psti2c, tmp, i2c_mode_write)) return 0;
	tmp = (Uint8) ((timeval >> 8) & 0xff);
	if (!i2c_mid_byte(psti2c, tmp, i2c_mode_write)) return 0;
	tmp = (Uint8) ((timeval >> 16) & 0xff);
	if (!i2c_mid_byte(psti2c, tmp, i2c_mode_write)) return 0;
	tmp = (Uint8) ((timeval >> 24) & 0xff);
	if (!i2c_mid_byte(psti2c, tmp, i2c_mode_write)) return 0;

	if (!i2c_close_byte(psti2c, 0, i2c_mode_write)) return 0;

	return 1;
	
}

Uint32 i2c_rtc_gettime(T_i2c *psti2c)
{
	Uint32 timeval;
	Uint8 tmp;

	if (!i2c_init_byte(psti2c, I2C_RTC_ADDR, i2c_mode_write)) return 0;
	if (!i2c_mid_byte(psti2c, 0, i2c_mode_write)) return 0;
	if (!i2c_init_byte(psti2c, I2C_RTC_ADDR, i2c_mode_read)) return 0;

	timeval = 0;

	tmp = i2c_mid_byte(psti2c, 0, i2c_mode_read) & 0xff;
	timeval = (Uint32) tmp;

	tmp = ((i2c_mid_byte(psti2c, 0, i2c_mode_read)) & 0xff);
	timeval |= (Uint32) (tmp << 8);

	tmp = ((i2c_mid_byte(psti2c, 0, i2c_mode_read)) & 0xff);
	timeval |= (Uint32) (tmp << 16);

	tmp = ((i2c_close_byte(psti2c, 0, i2c_mode_read)) & 0xff);
	timeval |= (Uint32) (tmp << 24);

	return timeval;
	
}