Example Code for Arduino-Read and Write RTC Time

Wiring Diagram

Sample Code

#include <Wire.h>

#define RTC_Address   0x32  //RTC_Address

unsigned char   date[7];

void setup()
{
  Wire.begin();
  Serial.begin(9600);
}

void loop()
{
  I2CWriteDate();//Write the Real-time Clock
  delay(100);

  while(1)
  {
    I2CReadDate();  //Read the Real-time Clock
    Data_process();//Process the data

    delay(1000);//延时1S
  }
}

//Read the Real-time data register of SD2403
void I2CReadDate(void)
{
  unsigned char n=0;

  Wire.requestFrom(RTC_Address,7);
  while(Wire.available())
  {
    date[n++]=Wire.read();
  }
  delayMicroseconds(1);
  Wire.endTransmission();
}

//Write the Real-time data register of SD2403
void I2CWriteDate(void)
{
  WriteTimeOn();

  Wire.beginTransmission(RTC_Address);
  Wire.write(byte(0));//Set the address for writing
  Wire.write(0x59);//second:59
  Wire.write(0x01);//minute:1
  Wire.write(0x95);//hour:15:00(24-hour format)
  Wire.write(0x03);//weekday:Wednesday
  Wire.write(0x26);//day:26th
  Wire.write(0x12);//month:December
  Wire.write(0x12);//year:2012
  Wire.endTransmission();

  Wire.beginTransmission(RTC_Address);
  Wire.write(0x12);   //Set the address for writing
  Wire.write(byte(0));
  Wire.endTransmission();

  WriteTimeOff();
}

//The program for allowing to write to SD2400
void WriteTimeOn(void)
{
  Wire.beginTransmission(RTC_Address);
  Wire.write(0x10);//Set the address for writing as 10H
  Wire.write(0x80);//Set WRTC1=1
  Wire.endTransmission();

  Wire.beginTransmission(RTC_Address);
  Wire.write(0x0F);//Set the address for writing as OFH
  Wire.write(0x84);//Set WRTC2=1,WRTC3=1
  Wire.endTransmission();
}

//The program for forbidding writing to SD2400
void WriteTimeOff(void)
{
  Wire.beginTransmission(RTC_Address);
  Wire.write(0x0F);   //Set the address for writing as OFH
  Wire.write(byte(0));//Set WRTC2=0,WRTC3=0
  Wire.write(byte(0));//Set WRTC1=0
  Wire.endTransmission();
}

//Process the time_data
void Data_process(void)
{
  unsigned char i;

  for(i=0;i<7;i++)
  {
    if(i!=2)
      date[i]=(((date[i]&0xf0)>>4)*10)+(date[i]&0x0f);
    else
    {
      date[2]=(date[2]&0x7f);
      date[2]=(((date[2]&0xf0)>>4)*10)+(date[2]&0x0f);
    }
  }
  // Use the serial monitor to see information being transmitted
  Serial.print("Sec = ");//second
  Serial.print(date[0]);
  Serial.print("   Min = ");//minute
  Serial.print(date[1]);
  Serial.print("   H = ");//hour
  Serial.print(date[2]);
  Serial.print("   W = ");//week
  Serial.print(date[3]);
  Serial.print("   D = ");//day
  Serial.print(date[4]);
  Serial.print("   M = ");//month
  Serial.print(date[5]);
  Serial.print("   Y = ");//year
  Serial.print(date[6]);

  Serial.println();
}