/*   I2C Slave Mode   RTC/UP Timer     BY M.K
     PIC12F1822       4MHz   mikroC Ver 5.01
     CONFIG1  :0x3F84   :0x3213
     I2C Address A2  register[0] and r_[1] = not use
                     r_[2]=59Sec r_[3]=59Min r_[4]=24Horu
     Last      2012/4/5      4/24 Hour
     Used ROM 194    (10%)
*/
#define  D_size 4
static   char  s05,r_data[D_size];
static   char  drn,i_temp,i_flag,T_count;
sbit     sLED  at PORTA.b5;   //b0=NC b1=SCL b2=SDA b3=NC b4=NC:NC=未使用


void Timer_Count()
{
//    0.5Sec UP Counter
      s05++;
      sLED=~sLED;
      if(s05==2){
         s05=0;
         r_data[2]++;
         if((r_data[2] & 0x0f)==0x0A){      // 1Sec
             r_data[2]+=6;
             if(r_data[2]==0x60){
                r_data[2]=0;
                r_data[3]++;                //1 minute
                if((r_data[3] & 0x0f)==0x0A){
                    r_data[3]+=6;           //10 minute
                    if(r_data[3]==0x60){
                       r_data[3]=0;
                       r_data[4]++;              //1 horu
                          if(r_data[4]==0x24)
                             r_data[4]=0;        //Max
                       if((r_data[4] & 0x0f)==0x0A){
                          r_data[4]+=6;          //10
                       }
                    }
                }
             }
         }
      }
}

void Data_send (){
     while((SSP1CON1.CKP)|(SSP1STAT.BF));
     SSP1BUF=r_data[drn];
     drn++;
}

void Interrupt()
{
   if (PIR1.SSP1IF == 1){
       PIR1.SSP1IF = 0;
       //
       if (SSP1STAT.b2 == 0) {         // R/W
            //Master Write mode
            if (SSP1STAT.b5 == 0){     //address set
                 i_temp = SSP1BUF;     // アドレス空読み
                 drn=0;
                 i_flag=0;
            }else{
                 if(i_flag==0){
                    drn = SSP1BUF;     // fast time.Register No
                    i_flag=1;
                 }else{
                    r_data[drn]=SSP1BUF;
                    drn++;
                 }
            }
        }else{
            //Master Read
            if (SSP1STAT.BF == 1) {    // Buffer Full Status bit
                 i_temp = SSP1BUF ;    // アドレス空読み
                 //
                 Data_send ();
            } else {
                 if (SSP1CON2.ACKSTAT == 0){     //ACK
                     Data_send ();
                  }
                  //NACK
            }
        }
        SSP1CON1.CKP = 1;
    }
    // Timer1
    if(PIR1.TMR1IF == 1){
        PIR1.TMR1IF = 0;
        TMR1H=0x0b;          //
        TMR1L=0xdb;          //
        Timer_Count();
    }
}

void main()
{
    OSCCON  =0b01101000;      //4MHz
    TRISA=0x0F;
    ANSELA=0;
//       I2C set
    SSP1STAT=0b10000000;
    SSP1CON1=0x26;            //SSP1EN + I2C Slave mode, 7-bit address
    SSP1ADD =0b10100010;      //RTCと同じAddress      A2
    SSP1MSK =0b11111110;
    SSP1CON2.SEN=0;
    PIE1.SSP1IE=1;
    PIR1.SSP1IF=0;
//       Timer1 set
    T1CON   =0b00110101;     //Pre=1/8 T1SYNC=off Tmer1=enable
    TMR1H=0x0b;              // 65535-62500=3035
    TMR1L=0xdb;              // 1uS*8*62500=0.5
    PIE1.TMR1IE=1;           //
    PIR1.TMR1IF=0;
//
    s05=0;
    drn=0;
    r_data[2]=0;             // Sec
    r_data[3]=0;             // Minute
    r_data[4]=0;             // Hour
    INTCON.PEIE=1;
    INTCON.GIE=1;
//
    while(1);                //LOOP
}