/*********************************************************************************
 *      Copyright:  (C) 2014 Guo Wenxue<guowenxue@gmail.com>
 *                  All rights reserved.
 *
 *       Filename:  gpio_i2c.c
 *    Description:  STM8 GPIOÄ£ÄâI2C´úÂë
 *                 
 *        Version:  1.0.0(09/28/2014)
 *         Author:  Guo Wenxue <guowenxue@gmail.com>
 *      ChangeLog:  1, Release initial version on "09/28/2014 10:58:17 PM"
 *                 
 ********************************************************************************/

#include "gpio_i2c.h"
#include "timing_delay.h"

/* ¿ªÊ¼ÐźţºSCLΪ¸ßµçƽʱ£¬SDAÓɸߵçƽÏòµÍµçƽÌø±ä£¬¿ªÊ¼´«ËÍÊý¾Ý. */
void gpio_i2c_start(void)
{
  SDA_MODE_OUT;
  
  SCL_LOW; 
  TIMDelay_N10us(1);  
  SDA_HIGH;
  TIMDelay_N10us(1); 
  SCL_HIGH;  
  TIMDelay_N10us(1);
  
  SDA_LOW;
  TIMDelay_N10us(1); 
  
  SCL_LOW; /* StartÖ®ºóBUS×ÜÏßÒ»°ã±»ÈÏΪ´¦ÓÚÕ¼Ïß״̬ */
  TIMDelay_N10us(1);  
}

/* ½áÊøÐźţºSCLΪ¸ßµçƽʱ£¬SDAÓɵ͵çƽÏò¸ßµçƽÌø±ä£¬½áÊø´«ËÍÊý¾Ý. */
void gpio_i2c_stop(void)
{
  SDA_MODE_OUT;    
  
  SCL_LOW;
  TIMDelay_N10us(1); 
  SDA_LOW;
  TIMDelay_N10us(1); 
  
  SCL_HIGH;
  TIMDelay_N10us(1);
  
  SDA_HIGH;
  TIMDelay_N10us(1);
}

/* ¶ÔÓÚ·´À¡ÓÐЧӦ´ðλACKµÄÒªÇóÊÇ£¬½ÓÊÕÆ÷ÔÚµÚ9¸öʱÖÓÂö³å֮ǰµÄ
 *µÍµçƽÆڼ佫SDAÏßÀ­µÍ£¬²¢ÇÒÈ·±£ÔÚ¸ÃʱÖӵĸߵçƽÆÚ¼äΪÎȶ¨µÄµÍµçƽ
 */
void gpio_i2c_send_ack(void)
{
  SDA_MODE_OUT;  

  /* ĬÈÏSCLÊǵ͵çƽ£¬ÏÖÔڸıäÊý¾Ý£¬µÍµçƽ±íʾACK */
  SDA_LOW;
  TIMDelay_N10us(1);

  /* ʱÖÓÏßÀ­¸ß²¢Î¬³ÖSDA״̬  */
  SCL_HIGH;
  TIMDelay_N10us(1);  
  
  /* »Ö¸´Ê±ÖÓÏßΪµÍµçƽ£¬×ÜÏßæ */
  SCL_LOW;
  TIMDelay_N10us(1);
}

/* NACK(°ÑÊý¾Ý×ÜÏߵĵçƽÀ­µÍ¸ß)À´±íʾÊý¾Ý³É¹¦Ê§°Ü */
void gpio_i2c_send_nak(void)
{
  SDA_MODE_OUT;  

  /* ĬÈÏSCLÊǵ͵çƽ£¬ÏÖÔڸıäÊý¾Ý£¬¸ßµçƽ±íʾNAK */
  SDA_HIGH;
  TIMDelay_N10us(1);

  /* ʱÖÓÏßÀ­¸ß²¢Î¬³ÖSDA״̬  */
  SCL_HIGH;
  TIMDelay_N10us(1);  
  
  /* »Ö¸´Ê±ÖÓÏßΪµÍµçƽ£¬×ÜÏßæ */
  SCL_LOW;
  TIMDelay_N10us(1);
}

/* I2C ×ÜÏ߶ÁÒ»¸öACKÐźŠ
 * ·µ»ØÖµ:0 ÊÕµ½ACK   1: ÊÕµ½NAK
 */
uint8_t gpio_i2c_wait_ack(void)
{
  uint8_t    rv;
  uint8_t    times = 200;  
  
  SDA_MODE_IN;

  /* ʱÖÓÏßÀ­¸ß */
  SCL_HIGH;
  TIMDelay_N10us(1);  
  
  do
  {
    times --;
  } while ( (SDA_DAT==1) && (times!=0) );
  
  if( !times )
  {
    /* µÈ´ý ACK ³¬Ê±£¬½ÓÊÕµ½NAK */
    rv = I2C_NAK;
    goto OUT;
  }
  
  /* µÈµ½ACK */
  SCL_LOW;
  TIMDelay_N10us(1);
  
  rv = I2C_ACK;

OUT:  
  return rv;
}

/* I2C×ÜÏß·¢ËÍÒ»¸ö×Ö½ÚÊý¾Ý:
 * ·µ»ØÖµ:0 ·¢Ëͳɹ¦£¬µÈµ½ACK   1: ·¢ËÍʧ°Ü,ÊÕµ½NAK
 */
uint8_t gpio_i2c_write_byte(uint8_t byte)
{
  int             i;
  uint8_t         rv = I2C_ACK;
  
  SDA_MODE_OUT;
  
  /* SCLΪµÍµçƽʱ,SDAÏß²ÅÄܸı䴫ÊäµÄbit; SCLΪ¸ßµçƽʱ,SDAÏß±£³ÖÎȶ¨ */
  for(i=7; i>=0; i--) /* MSB */
  {
    /*MSB: Êä³öÏàӦλµÄµçƽÐźŠ*/
    if( byte&(1<<i) )
      SDA_HIGH;
    else
      SDA_LOW;
    TIMDelay_N10us(1);
    
    SCL_HIGH;
    TIMDelay_N10us(1);    
    
    SCL_LOW;
    TIMDelay_N10us(1);
  }
  
  rv = gpio_i2c_wait_ack();
  return rv;
}

/* I2C×ÜÏß½ÓÊÕÒ»¸ö×Ö½ÚÊý¾Ý */
uint8_t gpio_i2c_read_byte(void)
{
  uint8_t  bit;
  uint8_t  byte = 0;
  
  SDA_MODE_IN;
  
  for(bit=0; bit<8; bit++)
  {
    byte <<= 1;
    SCL_HIGH;
    TIMDelay_N10us(2);
    
    if(SDA_DAT) 
      byte |= 1;
    
    SCL_LOW;
    TIMDelay_N10us(2);
  }	
  
  gpio_i2c_send_ack();
  return byte;
}

uint8_t gpio_i2c_read(uint8_t addr, uint8_t reg_addr)
{
    int rv;
    uint8_t data = 0;

    // Start condition
    gpio_i2c_start();

    // Send the slave address with write bit and check for ACK
    if (I2C_ACK != gpio_i2c_write_byte(addr | I2C_DIR_WRITE))
    {
        rv = I2C_ERROR;
        goto OUT;
    }

    // Send the register address and check for ACK
    if (I2C_ACK != gpio_i2c_write_byte(reg_addr))
    {
        rv = I2C_ERROR;
        goto OUT;
    }

    // Repeated start condition
    gpio_i2c_start();

    // Send the slave address with read bit and check for ACK
    if (I2C_ACK != gpio_i2c_write_byte(addr | I2C_DIR_READ))
    {
        rv = I2C_ERROR;
        goto OUT;
    }

    // Read the data byte
    data = gpio_i2c_read_byte();

    rv = data;

OUT:
    gpio_i2c_stop();
    if (rv == I2C_ERROR)
    {
        return -1;
    }
    return rv;
}



int gpio_i2c_write(uint8_t addr, uint8_t reg_addr, uint8_t data)
{
    int rv = I2C_OK;

    gpio_i2c_start();

    // Send the slave device address with the write bit and check for ACK
    if (I2C_ACK != gpio_i2c_write_byte(addr | I2C_DIR_WRITE))
    {
        rv = I2C_ERROR;
        goto OUT;
    }

    // Send the register address and check for ACK
    if (I2C_ACK != gpio_i2c_write_byte(reg_addr))
    {
        rv = I2C_ERROR;
        goto OUT;
    }

    // Send the data byte and check for ACK
    if (I2C_ACK != gpio_i2c_write_byte(data))
    {
        rv = I2C_ERROR;
    }

OUT:
    gpio_i2c_stop();
    return rv;
}