Hal_I2C.cpp

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/* Standard includes */
#include "Platform.h"
#include <Wire.h>
#include "Hal_I2C.h"
 
/* mainly assosiated to rtc - need to make it generic */
 
int16_t hal_rtc_i2c_init()
{
  Wire.begin();
  delay(100);  
  return 0;
}
 
/* api to read n bytes from addr */
int16_t hal_rtc_i2c_read(uint8_t addr, uint8_t *buffer,uint16_t length)
{
  uint16_t i;
  short count = 0;
  uint8_t writeResult = 0;
   while (length > 28)
  {
    hal_rtc_i2c_read(addr,buffer,28);
    buffer += 28;
    addr += 28;
    length -= 28;
  }
  
  Wire.beginTransmission(0x6f); // transmit to device (0x23)
  
 /* address bytes for rtc are from 00 to 0xff */
  Wire.write(addr);        // sends value byte  
  
  /* end the transmission but do not release the bus - usage is random data read use case from rtc */
  writeResult = Wire.endTransmission(false);//hold the bus to read the next data
 
  if (0 != writeResult)
  {
    return -1;//error case
  }
 
  Wire.requestFrom(0x6f, length);// request length bytes from slave device and end the transmission after this
  for(i=0;i<length;i++)
  {
    /* need to consider timout here */
    while(0 == Wire.available());//blocking call - at least one byte must be available
    buffer[i] = Wire.read();
  }
  
  return 0;
}
 
/* API to write data into particular location */
int16_t hal_rtc_i2c_write(uint8_t addr, uint8_t *buffer,uint16_t length)
{
  uint16_t i;
  byte writeResult = 0;
  if(0 == length)
  {
    return -1;
  }
  
  /* for read the lower bit must be set to 1 and for write set to 0 */
  Wire.beginTransmission(0x6f);
 
  /* address bytes for rtc are from 00 to 0xff */
  Wire.write(addr);        // sends value byte  
  
  /* check for each byte */
  for(i=0;i<length;i++)
  {
    Wire.write(*buffer++);//send the data to slave
  }
 
  /* end the transmission by stop bit */
  
  writeResult = Wire.endTransmission();//end the transmission by setting the stop bit
  
  if(0 != writeResult)
  {
    return writeResult;
  }
  return 0;
}
 
/* Nothing beyond this */