i2crtc.cpp

/*
 * I2CRTC.cpp - library for I2C RTC
  
  Copyright (c) Michael Margolis 2009
  This library is intended to be uses with Arduino Time.h library functions

  The library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  
  30 Dec 2009 - Initial release
  5 Sep 2011 updated for Arduino 1.0
  
  23 Dec 2013 -- modified by Ray Wang (Rayshobby LLC) to add support for MCP7940
 */


#ifdef ESP8266

#include "i2crtc.h"
#include <Wire.h>

static uint8_t _addrs[] = {DS1307_ADDR, MCP7940_ADDR, PCF8563_ADDR};

uint8_t I2CRTC::addr = 0;

I2CRTC::I2CRTC()
{
  Wire.begin();
}

bool I2CRTC::detect()
{
  addr = 0;
  for(uint8_t i = 0;i < sizeof(_addrs);i ++) {
    Wire.beginTransmission(_addrs[i]);
    Wire.write((uint8_t)0x00);
    if(Wire.endTransmission()==0) { // if chip detected successfully
      addr = _addrs[i];
      return true;
    }
  }
  return false;
}

// PUBLIC FUNCTIONS
time_t I2CRTC::get()   // Aquire data from buffer and convert to time_t
{
  tmElements_t tm;
  read(tm);
  return(makeTime(tm));
}

void I2CRTC::set(time_t t)
{
  tmElements_t tm;
  breakTime(t, tm);
  //tm.Second |= 0x80;  // stop the clock   ray: removed this step
  //write(tm); 
  //tm.Second &= 0x7f;  // start the clock  ray: moved to write function
  write(tm); 
}

// Aquire data from the RTC chip in BCD format
void I2CRTC::read( tmElements_t &tm)
{
  if(!addr) return;
  Wire.beginTransmission(addr);

  if(addr == PCF8563_ADDR) { 
      Wire.write((uint8_t)0x02);
      Wire.endTransmission();        
      Wire.requestFrom(addr, (uint8_t)7);
      tm.Second = bcd2dec(Wire.read() & 0x7f);
      tm.Minute = bcd2dec(Wire.read() & 0x7f);
      tm.Hour =   bcd2dec(Wire.read() & 0x3f);  // mask assumes 24hr clock
      tm.Day = bcd2dec(Wire.read() & 0x3f);
      tm.Wday = bcd2dec(Wire.read() & 0x07);
      tm.Month = bcd2dec(Wire.read() & 0x1f);   // fix bug for MCP7940
      tm.Year = (bcd2dec(Wire.read()));
  } else {
      Wire.write((uint8_t)0x00); 
      Wire.endTransmission();        
      Wire.requestFrom(addr, (uint8_t)7);
      tm.Second = bcd2dec(Wire.read() & 0x7f);
      tm.Minute = bcd2dec(Wire.read() & 0x7f);
      tm.Hour =   bcd2dec(Wire.read() & 0x3f);  // mask assumes 24hr clock
      tm.Wday = bcd2dec(Wire.read() & 0x07);
      tm.Day = bcd2dec(Wire.read() & 0x3f);
      tm.Month = bcd2dec(Wire.read() & 0x1f);   // fix bug for MCP7940
      tm.Year = y2kYearToTm((bcd2dec(Wire.read())));
  }
}

void I2CRTC::write(tmElements_t &tm)
{
  if(!addr) return;
  switch(addr) {
    case DS1307_ADDR:
      Wire.beginTransmission(addr);  
      Wire.write((uint8_t)0x00); // reset register pointer  
      Wire.write(dec2bcd(tm.Second) & 0x7f);  // ray: start clock by setting CH bit low
      Wire.write(dec2bcd(tm.Minute));
      Wire.write(dec2bcd(tm.Hour));      // sets 24 hour format
      Wire.write(dec2bcd(tm.Wday));   
      Wire.write(dec2bcd(tm.Day));
      Wire.write(dec2bcd(tm.Month));
      Wire.write(dec2bcd(tmYearToY2k(tm.Year))); 
      Wire.endTransmission();
      break;
    case MCP7940_ADDR:
      Wire.beginTransmission(addr);  
      Wire.write((uint8_t)0x00); // reset register pointer  
      Wire.write(dec2bcd(tm.Second) | 0x80);  // ray: start clock by setting ST bit high
      Wire.write(dec2bcd(tm.Minute));
      Wire.write(dec2bcd(tm.Hour));      // sets 24 hour format
      Wire.write(dec2bcd(tm.Wday) | 0x08);  // ray: turn on battery backup by setting VBATEN bit high
      Wire.write(dec2bcd(tm.Day));
      Wire.write(dec2bcd(tm.Month));
      Wire.write(dec2bcd(tmYearToY2k(tm.Year))); 
      Wire.endTransmission();
      break;
    case PCF8563_ADDR:
      Wire.beginTransmission(addr);  
      Wire.write((uint8_t)0x02); // reset register pointer  
      Wire.write(dec2bcd(tm.Second) & 0x7f);
      Wire.write(dec2bcd(tm.Minute));
      Wire.write(dec2bcd(tm.Hour));      // sets 24 hour format
      Wire.write(dec2bcd(tm.Day));
      Wire.write(dec2bcd(tm.Wday));   
      Wire.write(dec2bcd(tm.Month));
      Wire.write(dec2bcd(tm.Year)); 
      Wire.endTransmission();
      break;
  }    
}

// Convert Decimal to Binary Coded Decimal (BCD)
uint8_t I2CRTC::dec2bcd(uint8_t num)
{
  return ((num/10 * 16) + (num % 10));
}

// Convert Binary Coded Decimal (BCD) to Decimal
uint8_t I2CRTC::bcd2dec(uint8_t num)
{
  return ((num/16 * 10) + (num % 16));
}

I2CRTC RTC = I2CRTC(); // create an instance for the user

#endif