display units and tens

[hhhsssmmm]

hello

I have successfully interfaced a PIC18F4423 and DS1307 via I2C interface using C18. For now I can read the seconds ticking away and can partailly dispay them on a 20x2 LCD.

Now let me explain my problem.

I can not get the 'units' (right most digit of the second) to roll over back to '0' after it passes '9'. I know i have to break the byte variable in to two nibbles but i try and i get garbage with 'units' after the count passes 9....it starts showing HEX numbers A to F and then random ASCII characters. The left most digit ('tens') I can display perfectly and they even roll over after passing '5' ... (0 - 5).

Below is my code segment where im breaking the 'seconds' byte variable into two nibbles...plz can someone take a look at it and kindly sugget a fix for this problem.

Thank you

hhhsssmmm

//DISPLAYING the 'TENS' of the second
        HIGH_nibble = seconds;        
        HIGH_nibble = HIGH_nibble >> 4;
        //convert ASCII
        HIGH_nibble += '0';     
        SendLCD(0x80,0); //activate LCD line 1 ... Column 1                         
        //display on LCD
        SendLCD(HIGH_nibble,1);  
       


        //DISPLAYING the 'UNITS' of the second
        seconds = seconds << 4;
        //convert ASCII
        seconds += '0';     
        SendLCD(0x81,0); //activate LCD line 1 ... Column 2                     
        //display on LCD
        SendLCD(seconds,1);

 

[GSM Man]

The least significant digit of the seconds is stored in the lower 4 bits (0-3). In your code for the 'units' you are shifting it into the upper 4 bits before adding the '0'. Remove the line " seconds = seconds << 4;" and it should work.

 

[mfarooq1]

i recommend to use separate bytes for unit and ten.

 

[hhhsssmmm]

thank you so all so much for ur kind input

I have solved the problem and here is the fixed code and im now happy that the seconds are displaying very nicely and ticking away from 00-59 and then rolling over again to 00 and starting again...

problem was simply not breaking up the BCD bytes properly into the respective nibbles

//EXTRACTING the 'TENS' of the second & converting it to ASCII for LCD
		HIGH_nibble = BCD; 		
		HIGH_nibble = (HIGH_nibble >> 4) + '0';		
	
		//EXTRACTING the 'UNITS' of the second & converting it to ASCII for LCD
		BCD = (BCD & 0x0F) + '0';

		//activate LCD line 1 & display 'TENS' in Column 1 
	    SendLCD(0x80,0);                      			
		SendLCD(HIGH_nibble,1);   	
		
		//activate LCD line 1 & display 'UNITS' in Column 2	
	    SendLCD(0x81,0); 
		SendLCD(BCD,1);

Thanks so much again
hhhsssmmm