[SOLVED] phase lock loop using microcontroller initial step using ADC

[patelvivekv1993]

i want to design a Phase lock loop using microcontroller with memory block method(i.e not using hardwired XORing)....i know its somewhat hard and complicated so i wanted to start by starting with small small steps........
i am using PIC18F4550 right now i have configured its ADC with TAD as 64Tosc and acquiring time as 2Tad and i am using 48Mhz crystal so calculating with that values i think my sampling freqeuncy is 250KHz ??????
i am using mikro c Pro for PIC and proteus for simulation.......
Now i wanna know that 250KHz samling frequency means that if i provide a 250KHz sine wave to the analog channel my all output must be 0????(or nearer to 0) as at that time the sampling would be done...
i know that it will be also the case for double and half frequency....but thats not my concern right now....

what i wanna do right now as initial step towards PLL is find out whether the signal supplied to the controller is of a certain frequency or not....so is my logic correct???

becuase i have simulated the above with mikro c and proteus and i m gettting the wrong results i.e instead of getting 0 at 250KHz i am getting it at 250Hz

i am attaching my mikro c project as well as proteus file and writing the code below

//Memory Card Chip Select Connection
sfr sbit Mmc_Chip_Select at RB2_bit;
sfr sbit Mmc_Chip_Select_Direction at TRISB2_bit;


unsigned char filename[] = "vivek.txt";
unsigned char error;
unsigned int temp;
double adc_value,voltage;
unsigned char tagline[] = " hello i am vivek using mikro c ";
unsigned char voltage_Log[7];
void main()
{
 unsigned char ones,point_ones,point_hundreds,newline='\r\n';
 TRISD =0x00;
 ADCON0 = 0b00000001;    //A/D Converter Power Up
 ADCON1 = 0x00;          //All Analog Channels
 ADCON2 = 0b10111110;    //Right Justfied and Slowest Clock for better accuracy
 ADC_Init();

 SPI1_Init();
 SPI1_Init_Advanced(_SPI_MASTER_OSC_DIV64, _SPI_DATA_SAMPLE_MIDDLE, _SPI_CLK_IDLE_LOW, _SPI_LOW_2_HIGH);

 error = MMC_Init();
 while(error == 1)
 {
  LATD=0xff;
  error = MMC_Init();
 }
  LATD =0x00;
 MMC_Fat_Init();
 SPI1_Init_Advanced(_SPI_MASTER_OSC_DIV4, _SPI_DATA_SAMPLE_MIDDLE, _SPI_CLK_IDLE_LOW, _SPI_LOW_2_HIGH);

 Mmc_Fat_Assign(&filename,0x80);
 while(1)
 {
  adc_value = ADC_Read(0);      //Read Temperature from ADC
  voltage=adc_value*5/1023;
  ones = voltage/1;
  ones = ones | 0x30;
  temp=voltage*10;
  point_ones = temp%10;
  point_ones = point_ones | 0x30;
  temp=voltage*100;
  point_hundreds = temp%10;
  point_hundreds = point_hundreds | 0x30;
  voltage_Log[0] = ones;
  voltage_Log[1] = '.';
  voltage_Log[2] = point_ones;
  voltage_Log[3] = point_hundreds;
  voltage_Log[4] = 'V';
  voltage_Log[5] = '\r';
  voltage_Log[6] = '\n';
  Mmc_Fat_Append();
  //Mmc_Fat_Write(tagline,sizeof(tagline));
  Mmc_Fat_Write(voltage_Log,sizeof(voltage_Log));
}
}

and if someone knows or has done PLL can u please give me some deep insight on actually how it is done using controller????

please help me here.....
thnx in advance.....