DS1307 RTC with 8051 ? comes while printing

[td micro]

hi
i our project,we have connected 89lv51 with RTC DS1307.
here we set the time as
time23:59:36
date31/10/12
and displayed on hyperterminal.at that time, we are getting the time.it is incrementing and displayed on hyper.but some times, it is showing ?.

time23:59:36
date31/10/12

time23:59:37
date31/10/12

time??:??:??
date??/??/??

time??:??:??
date??/??/??

time23:59:40
date31/10/12

time23:59:41
date31/10/12

time??:??:??
date??/??/??
......................................
.................................
..............................
time00:01:51
date01/11/12

time00:01:52
date01/11/12


time??:??:??
date??/??/??

time00:01:54
date01/11/12

time00:01:55
date01/11/12

time00:01:57
date1?/??/??

time??:??:??
date??/??/??

time??:??:??
date??/??/??

time??:??:??
date??/??/??

time00:02:02
date01/11/12

time00:02:03
date01/11/12

time1?:02:05
date??/??/??

time??:??:??
date??/??/??

time??:??:??
date??/??/??

time00:02:09
date01/11/12

time00:02:10
date01/11/12

time00:02:11
date01/11/12

time??:??

in this, time and date are incrementing in correct way.but , some times, '?' is coming..
please help me to solve this...

 

[bigdogguru]

I would suggest posting your code using the code/syntax tags, so we may examine it.

BigDog

 

[td micro]

thanks for reply...

actually there are 2 programs with me.one is written by me and another one is that i got from internet.in both programs, while executing i m getting question mark frequently.
here is the code

///// main.c
 #include<reg51.h>
#include<stdio.h>
#include<ds1307.h>
#include<serial.h>
#include<delay.h>

unsigned char  RTC_ARR[7];  // Buffer for second,minute,.....,year
void SendByte1(unsigned char);
unsigned char p;
void WriteSerial(unsigned char*);
void SendByte(unsigned char s);
//---------------------------------------
// Main program
//---------------------------------------
 void main(void)
{


	InitSerial();  		// Initialize serial port
	
	//printf("%s",&Int2Day(1));
	   DelayMs(100);
	
	//-----------------------------------
	// Setup time and enable oscillator
	//-----------------------------------
	  
	ReadRTC(&RTC_ARR[0]);        
	RTC_ARR[0] = RTC_ARR[0] & 0x7F;	// enable oscillator (bit 7=0)
	RTC_ARR[1] = 0x59;	// minute = 59
	RTC_ARR[2] = 0x23;	// hour = 05 ,24-hour mode(bit 6=0)
	RTC_ARR[3] = 0x04;	// Day = 1 or sunday
	RTC_ARR[4] = 0x31;	// Date = 30
	RTC_ARR[5] = 0x10;	// month = August
	RTC_ARR[6] = 0x12;	// year = 05 or 2005
	WriteRTC(&RTC_ARR[0]);	// Set RTC
	   DelayMs(100);

	
	while(1)
	{
		  DelayMs(100);
		ReadRTC(&RTC_ARR[0]);        
		  DelayMs(100);
		 	
			 	
	 	//WriteSerial("day");
		//WriteSerial(Int2Day(RTC_ARR[3]));
		//WriteSerial("\r\n");
		WriteSerial("time");
		SendByte1(RTC_ARR[2]); //DelayMs(100);
		WriteSerial(":");
		SendByte1(RTC_ARR[1]);	//DelayMs(100);
		WriteSerial(":");
		SendByte1(RTC_ARR[0]);	//DelayMs(100);
		WriteSerial("\r\n");
		WriteSerial("date");
		SendByte1(RTC_ARR[4]);	 //DelayMs(100);
		WriteSerial("/");
		SendByte1(RTC_ARR[5]);	// DelayMs(100);
		//WriteSerial(Int2Month(RTC_ARR[5]));
		 WriteSerial("/");
		 SendByte1(RTC_ARR[6]);	//DelayMs(100);

		 WriteSerial("\r\n");
	
		 WriteSerial("\r\n");
				
		  DelayMs(500);
	}
}

 void SendByte1(unsigned char value)
{
	unsigned char buf = 0;	
	
	buf = value & 0xF0;		/* Filter for high byte */
	buf = (buf>>4)|(0x30);		/* Convert  to ascii code */

 SendByte(buf);			

	buf = value & 0x0F;		/* Filter for low byte */
	buf = buf | 0x30;       	/* Convert to ascii code */

 SendByte(buf);			
 		
}


/////////////ds1307.c

 #include<reg51.h>
#include<delay.h>
#include<intrins.h>

#define ACK		1
#define NO_ACK	0
#define SLAVE	0xD0
#define WRITE   0x00
#define READ    0x01
#define ERR_ACK 0x01


unsigned char i;

const unsigned char * DayStr[7]  =     {{"Sun"},
				   						{"Mon"},
				   						{"Tue"},
				   						{"Wen"},
				   						{"The"},
				   						{"Fri"},
				   						{"Sat"}};


const unsigned char * MonthStr[12]    ={{"Jan"},
										{"Feb"},
										{"Mar"},
										{"Apr"},
										{"May"},
										{"Jun"},
										{"Jul"},
										{"Aug"},
										{"Sep"},
										{"Oct"},
										{"Nov"},
										{"Dec"}};


sbit SDA  =  P2^1;	// connect to SDA pin (Data)
sbit SCL  =  P2^0;	// connect to SCL pin (Clock)



//-------------------------------
// Convert BCD 1 byte to HEX 1 byte
//-------------------------------
unsigned char BCD2HEX(unsigned int bcd)
{
	unsigned char temp;
	temp=((bcd>>8)*100)|((bcd>>4)*10)|(bcd&0x0f);
	return temp;
	
}

//-------------------------------
// start I2C
//-------------------------------
void Start(void)
{
    SDA = 1;
	SCL = 1;
	_nop_();_nop_();   _nop_();_nop_();_nop_();_nop_();
	SDA = 0;
	_nop_();_nop_();  _nop_();_nop_();	_nop_();_nop_();
	SCL = 0;
	_nop_();_nop_();   _nop_();_nop_();	_nop_();_nop_();
}

//-------------------------------
// stop I2C
//-------------------------------
void Stop(void)
{
	SDA = 0;	    	
	_nop_();_nop_();  
	SCL = 1;
	_nop_();_nop_();   
	SDA = 1;	
}

//-------------------------------
// Write I2C
//-------------------------------
void WriteI2C(unsigned char Data)
{    

	for (i=0;i<8;i++)
	{
        SDA = (Data & 0x80) ? 1:0;
		SCL=1;_nop_();SCL=0;
		Data<<=1;
	}

  	SCL = 1; 
	_nop_();_nop_();
	SCL = 0;

}

//-------------------------------
// Read I2C
//-------------------------------
unsigned char ReadI2C(bit ACK_Bit)
{
    
    unsigned char Data=0;

    SDA = 1;
	for (i=0;i<8;i++)
	{
		SCL   = 1;	
		Data<<= 1;
		Data  = (Data | SDA);		
		SCL   = 0;
		_nop_(); _nop_();
	}
    
 	if (ACK_Bit == 1)
	SDA = 0; // Send ACK		
	else		
	SDA = 1; // Send NO ACK				

	_nop_();_nop_();
	SCL = 1;		
	_nop_();_nop_(); 
	SCL = 0;
	
	return Data;
}

//-------------------------------
// Read 1 byte form I2C
//-------------------------------
unsigned char ReadBYTE(unsigned char Addr)
{
   	unsigned char Data;
	Start();		  
	WriteI2C(0xD0);	 
	WriteI2C(Addr);	 
	Start();		
	WriteI2C(0xD1);	  
	Data = ReadI2C(NO_ACK);	
	Stop();
   	return(Data);
}

//-------------------------------
// Write 1 byte to I2C
//-------------------------------
void WriteBYTE(unsigned char Addr,unsigned char Data)
{
	Start();
	WriteI2C(0xD0);
	WriteI2C(Addr);
	WriteI2C(Data);
	Stop();	
}

//-------------------------------
// Read RTC (all real time)
//-------------------------------
void ReadRTC(unsigned char * buff)
{
	
	
	Start();		  
	WriteI2C(0xD0);	  
	WriteI2C(0x00);	   

	Start();
	WriteI2C(0xD1);	 
	*(buff+0)=ReadI2C(ACK);	// Second
		
			  
	*(buff+1)=ReadI2C(ACK);	// Minute
			   
	*(buff+2)=ReadI2C(ACK);	// hour
			
				  
	*(buff+3)=ReadI2C(ACK);	// Day
			 
				  
	*(buff+4)=ReadI2C(ACK);	// date
				
				  
	*(buff+5)=ReadI2C(ACK);	// month
				 
					 
	*(buff+6)=ReadI2C(NO_ACK);	// year
				 
	Stop();		
}

//-------------------------------
// Write RTC
//-------------------------------
void WriteRTC(unsigned char *buff)
{

	Start();
	WriteI2C(0xD0);
	WriteI2C(0x00);	
	WriteI2C(*(buff+0));	
	WriteI2C(*(buff+1));
	WriteI2C(*(buff+2));
	WriteI2C(*(buff+3));
	WriteI2C(*(buff+4));
	WriteI2C(*(buff+5));
	WriteI2C(*(buff+6));	
	Stop();	
}


char * Int2Day(unsigned char day)
{
	return DayStr[day-1];
}


char * Int2Month(unsigned char month)
{
  return MonthStr[BCD2HEX(month)-1];
}

 

[td micro]

hi,
the above programs works well some times..but after 2 display, it is showing '?' . please guide me to solve the problem.

 

[td micro]

please help me... is there any mistake in my program???