AVR Freaks

I made this DS1307 based clock to run with an ATMega8 running at 8 MHz internal clock. Now, the clock works flawlessly, but the LM35 connected to the circuit to show the room temperature doesn't work.

I used libraries from Extreme Electronics.

LCD is connected (D4 to D7) at PD3 to PD6. RS at PB2, RW at PB0, E at PD7.

Keys:

Enter Menu: PC2

Shift cursor left: PC0

Shift cursor right: PC1

Exit: PC6

C5, C4 used by DS1307.

This leaves only PC3 (ADC channel 3) to use with LM35. So I connected the LM35 output with PC3.

But it always displays 255C (AREF voltage itself). Even when I pullup PC3 to ground, the temp doesn't show 0C, rather it always shows 255C.

The compilation completes successfully without any error/warning.

What am I doing wrong? 

Is it possible that PC3 is not being used by ADC? Do I need to use an ATMega16 for this kind of project?

#include <avr/io.h>
#include <avr/pgmspace.h>
#include <util/delay.h>

#include "lib\lcd\lcd_hd44780_avr.h"
#include "lib\rtcc\clock.h"
#include "lib\keypad\keypad.h"

typedef bool uint8_t;

#define TRUE	1
#define FALSE	0

bool SetTime();

int main(void)
{
	
	int tempC;
	ADCSRA = (1<<ADEN)|(7 << ADPS0);        // Enable, div128
	ADMUX = (3 << REFS0)|(1<<ADLAR)|(3<<MUX0);  // VREF=2.56V, 8-bit, channel #0 is on PA0 pin
	
	//Initialize the LCD module
	LCDInit(LS_NONE);
	
	//Write a intro text
	LCDWriteFStringXY(0,0,PSTR("   Bagho's"));
	LCDWriteFStringXY(0,1,PSTR("    Clock"));
	
	_delay_ms(2000);
	
	LCDClear();
	//Initialize the Clock Module
	if(!ClockInit())
	{
		//If we fail to initialize then warn user
		LCDClear();
		LCDWriteString("Error !");
		LCDWriteStringXY(0,1,"DS1307 Not Found");

		while(1); //Halt
	}
	
	//Initialize the keypad
	KeypadInit();
	
	//Now Read and display time
	char Time[12];	//hh:mm:ss AM/PM
	
	while(1)
	{
		
		ADCSRA |= (1<<ADSC);          // Start Conversion
		while (ADCSRA & (1<<ADSC));   // wait for completion

		tempC = ADCH;
		LCDClear();
		
		
		//Loop, read time from chip and show on lcd
		while(1)
		{
		
			//Get the Current Time as a String
			if(!GetTimeString(Time))
			{
				/*
				If return value is false then some error has occurred
			
				Check
				 ->DS1307 Installed Properly
				*/

				LCDClear();
				LCDWriteString("xBoard MINI v2.0");
				LCDWriteStringXY(0,1,"I2C i/o Error !");
			
				while(1);//halt
			}

			//Display it
			LCDWriteIntXY(0,0, tempC, 3);
			LCDWriteStringXY(4,0, "Degrees")
			LCDWriteStringXY(2,1,Time);
		
			//Check input for ENTER key
			uint8_t key = GetKeypadCmd(FALSE);
		
			if(key==KEY_ENTER)
			{
				//Enter time setup
				SetTime();
				
				break;
			}
		
			_delay_ms(500);
		}		
		
	}
	
}

bool SetTime()
{

	uint8_t hr,min,sec,am_pm;

	//Get Seconds
	sec=GetSecond();

	//Get Minute
	min=GetMinute();

	//Get Hour
	hr=GetHour();

	//Get AM/PM
	am_pm=GetAmPm();

	//If Hour is 0 make it 12, as 00:00:00 invalid time
	if(hr==0 && min==0 && sec==0) hr=12;

	uint8_t sel=0;
	
	bool done=FALSE;

	while(!done)
	{
		LCDClear();

		LCDWriteString("00:00:00    <OK>");
		
		LCDWriteIntXY(0,0,hr,2);
		LCDWriteIntXY(3,0,min,2);
		LCDWriteIntXY(6,0,sec,2);

		if(am_pm)
		{
			LCDWriteStringXY(9,0,"PM");
		}
		else
		{
			LCDWriteStringXY(9,0,"AM");
		}

		//Draw Pointer
		LCDWriteStringXY(sel*3,1,"^^");
		
		uint8_t key=GetKeypadCmd(1);

		switch(key)
		{
			case KEY_RIGHT:
			
				if(sel==0)
				{
					//Hour
					if(hr==12)
					{
						hr=1;
					}
					else
					{
						hr++;
					}
				}

				if(sel==1)
				{
					//Min
					if(min==59)
					{
						min=0;
					}
					else
					{
						min++;
					}
				}

				if(sel==2)
				{
					//Sec
					if(sec==59)
					{
						sec=0;
					}
					else
					{
						sec++;
					}
				}

				if(sel==3)
				{
					//AM-PM
					if(am_pm==0)
					{
						am_pm=1;
					}
					else
					{
						am_pm=0;
					}
				}
				if(sel == 4)
				{
					//OK
					done=TRUE;
				}
			
			break;
			
			case KEY_LEFT:
			
				if(sel==0)
				{
					//Hour
					if(hr==1)
					{
						hr=12;
					}
					else
					{
						hr--;
					}
				}

				if(sel==1)
				{
					//Min
					if(min==0)
					{
						min=59;
					}
					else
					{
						min--;
					}
				}

				if(sel==2)
				{
					//Sec
					if(sec==0)
					{
						sec=59;
					}
					else
					{
						sec--;
					}
				}

				if(sel==3)
				{
					//AM-PM
					if(am_pm==0)
					{
						am_pm=1;
					}
					else
					{
						am_pm=0;
					}
				}
				if(sel == 4)
				{
					//OK
					done=TRUE;
				}
			
			break;
			
			case KEY_ENTER:
			
			//Change Selection
			if(sel==4)
				sel=0;
			else
				sel++;
			
			break;
		}

	}

	//Now write time back to RTC Module
	if(!SetSecond(sec))
	{
		LCDClear();
		LCDWriteString("Error !");
		LCDWriteStringXY(0,1,"Cannot Set Time");
		return 0;
	}
	if(!SetMinute(min))
	{
		LCDClear();
		LCDWriteString("Error !");
		LCDWriteStringXY(0,1,"Cannot Set Time");
		return 0;
	}
	if(!SetHour(hr))
	{
		LCDClear();
		LCDWriteString("Error !");
		LCDWriteStringXY(0,1,"Cannot Set Time");
		return 0;
	}
	if(!SetAmPm(am_pm))
	{
		LCDClear();
		LCDWriteString("Error !");
		LCDWriteStringXY(0,1,"Cannot Set Time");
		return 0;
	}


	//Show Message
	LCDClear();
	LCDWriteString("Message !");
	LCDWriteStringXY(0,1,"Main Time Set");

	uint8_t i;
	for(i=0;i<100;i++)
	_delay_loop_2(0);
	
	return 1;

}