STS_E2/AirQuality/Src/i2c_hal.c

/**
  ******************************************************************************
  * @file           : i2c_hal.c
	* @author  				: zsq
	* @version 				: V1.0
	* @date    				: 2019-06-27
  * @brief          : I2C hardware abstraction layer
  ******************************************************************************
    * @attention
  *
  * Copyright (c) 2019 YUNHORN(Shenzhen YunHorn Technology Co., Ltd
  * All rights reserved.
  *
  ******************************************************************************
  */
//-- Includes -----------------------------------------------------------------
#include "i2c_hal.h"


#include "main.h"
#include "stdio.h"
//-- Defines ------------------------------------------------------------------
// I2C IO-Pins                        /* -- adapt the defines for your uC -- */

// SDA on port A, bit 10
#define SDA_LOW()  (GPIOA->BSRR = 0x04000000) // set SDA to low
#define SDA_OPEN() (GPIOA->BSRR = 0x00000400) // set SDA to open-drain
#define SDA_READ   (GPIOA->IDR  & 0x0400)     // read SDA

// SCL on port A, bit 9              /* -- adapt the defines for your uC -- */
#define SCL_LOW()  (GPIOA->BSRR = 0x02000000) // set SCL to low
#define SCL_OPEN() (GPIOA->BSRR = 0x00000200) // set SCL to open-drain
#define SCL_READ   (GPIOA->IDR  & 0x0200)     // read SCL

//-- Static function prototypes -----------------------------------------------
static etError I2c_WaitWhileClockStreching(u8t timeout);

//-----------------------------------------------------------------------------
void I2c_Init(void)                      /* -- adapt the init for your uC -- */
{
  RCC->APB2ENR |= 0x00000008;  // I/O port B clock enabled
  
  SDA_OPEN();                  // I2C-bus idle mode SDA released
  SCL_OPEN();                  // I2C-bus idle mode SCL released
  

	LL_GPIO_InitTypeDef GPIO_InitStruct;
	
	GPIO_InitStruct.Pin = (LL_GPIO_PIN_9 | LL_GPIO_PIN_10);
  GPIO_InitStruct.Mode = LL_GPIO_MODE_OUTPUT;
  GPIO_InitStruct.OutputType = LL_GPIO_OUTPUT_OPENDRAIN;
  GPIO_InitStruct.Speed = LL_GPIO_SPEED_FREQ_HIGH;
  GPIO_InitStruct.Pull = LL_GPIO_PULL_NO;
  LL_GPIO_Init(GPIOA, &GPIO_InitStruct);
	
}

//-----------------------------------------------------------------------------
void I2c_StartCondition(void)
{
  SDA_OPEN();
  DelayMicroSeconds(1);
  SCL_OPEN();
  DelayMicroSeconds(1);
  SDA_LOW();
  DelayMicroSeconds(10);  // hold time start condition (t_HD;STA)
  SCL_LOW();
  DelayMicroSeconds(10);
}

//-----------------------------------------------------------------------------
void I2c_StopCondition(void)
{
  SCL_LOW();
  DelayMicroSeconds(1);
  SDA_LOW();
  DelayMicroSeconds(1);
  SCL_OPEN();
  DelayMicroSeconds(10);  // set-up time stop condition (t_SU;STO)
  SDA_OPEN();
  DelayMicroSeconds(10);
}

//-----------------------------------------------------------------------------
etError I2c_WriteByte(u8t txByte)
{
  etError error = NO_ERROR;
  u8t     mask;
  for(mask = 0x80; mask > 0; mask >>= 1)// shift bit for masking (8 times)
  {
    if((mask & txByte) == 0) SDA_LOW(); // masking txByte, write bit to SDA-Line
    else                     SDA_OPEN();
    DelayMicroSeconds(1);               // data set-up time (t_SU;DAT)
    SCL_OPEN();                         // generate clock pulse on SCL
    DelayMicroSeconds(5);               // SCL high time (t_HIGH)
    SCL_LOW();
    DelayMicroSeconds(1);               // data hold time(t_HD;DAT)
  }
  SDA_OPEN();                           // release SDA-line
  SCL_OPEN();                           // clk #9 for ack
  DelayMicroSeconds(1);                 // data set-up time (t_SU;DAT)
  if(SDA_READ) error = ACK_ERROR;       // check ack from i2c slave
  SCL_LOW();
  DelayMicroSeconds(20);                // wait to see byte package on scope
  return error;                         // return error code
}

//-----------------------------------------------------------------------------
etError I2c_ReadByte(u8t *rxByte, etI2cAck ack, u8t timeout)
{
  etError error = NO_ERROR;
  u8t mask;
  *rxByte = 0x00;
  SDA_OPEN();                            // release SDA-line
  for(mask = 0x80; mask > 0; mask >>= 1) // shift bit for masking (8 times)
  { 
    SCL_OPEN();                          // start clock on SCL-line
    DelayMicroSeconds(1);                // clock set-up time (t_SU;CLK)
    error = I2c_WaitWhileClockStreching(timeout);// wait while clock streching
    DelayMicroSeconds(3);                // SCL high time (t_HIGH)
    if(SDA_READ) *rxByte |= mask;        // read bit
    SCL_LOW();
    DelayMicroSeconds(1);                // data hold time(t_HD;DAT)
  }
  if(ack == ACK) SDA_LOW();              // send acknowledge if necessary
  else           SDA_OPEN();
  DelayMicroSeconds(1);                  // data set-up time (t_SU;DAT)
  SCL_OPEN();                            // clk #9 for ack
  DelayMicroSeconds(5);                  // SCL high time (t_HIGH)
  SCL_LOW();
  SDA_OPEN();                            // release SDA-line
  DelayMicroSeconds(20);                 // wait to see byte package on scope
  
  return error;                          // return with no error
}

//-----------------------------------------------------------------------------
etError I2c_GeneralCallReset(void)
{
  etError error;
  
  I2c_StartCondition();
                        error = I2c_WriteByte(0x00);
  if(error == NO_ERROR) error = I2c_WriteByte(0x06);
  
  return error;
}

//-----------------------------------------------------------------------------
static etError I2c_WaitWhileClockStreching(u8t timeout)
{
  etError error = NO_ERROR;
  
  while(SCL_READ == 0)
  {
    if(timeout-- == 0) return TIMEOUT_ERROR;
		DelayMicroSeconds(1000);
  }
  
  return error;
}