Thread: Help! Embedded C GPIO Issue

I have this project I am doing and I am a beginner. I am trying to read a square pulse train coming into one of my digital GPIO pins of my PIC12 microcontroller. I have to "sample" and then store the incoming signal so that I have a bunch of 1's and 0's saved (possibly in an array). I have to save the number of 1's and 0's I get(which are sampled in packets of 8, 4 times over) and calculate the number of 1's or 0's into an average.Anyone know how I can either start of accomplish this in C code?

Here is the code I have so far. Please keep in mind that I have no idea what I am doing with these arrays:

Code:

#define one_or_zero GP4	//GP4 is the PIC's digital input expecting 
						//a pulse train of 1's and 0's at 50% duty cycle


int sampleA_result;	//These are used to store the bits in different 
					//"locations" of the array
int sampleB_result;
int sampleC_result;
int sampleD_result;
char sampleA0[8]; //Declaring these arrays to be 8 "bits" long.
char sampleA1[8];	//Both A0 and A1 are 8 long because it is possible
					//in my application to be 
					//getting nothing but 0's or nothing but 1's.
char sampleB0[8];
char sampleB1[8];


char sampleC0[8];
char sampleC1[8];


char sampleD0[8];
char sampleD1[8];


int sample_result[32]; //This is the average for all 32 bits 
					   //that have been sampled either 1 or 0
int i;


main()
{
	while(1)
	{
		//initializations,etc. go here
		sleep();			//I don't really know how to slow the pulse 
							//train down to easily sample it at my sampling frequency
		getONEorZERO();
		average();
	}
}
/////////////////////////////////////////////////
void sleep(void)
{
//something goes here


}
/////////////////////////////////////////////////
void getONEorZERO(void)	//This function gets 4 samples(A through D)
						//, all 8 bits long from the General Purpose input.
{
	char A=1;	//Flag for SampleA0,A1 performed first.
	char B=0;	//Flag for SampleB0,B1 performed second.
	char C=0;	//Flag for SampleC0,C1 performed third.
	char D=0;	//Flag for SampleD0,D1 performed last.
	if(A=1)
	{
		for(i=0;i<8;i++)
		{
			if(one_or_zero==0)
			{
				sampleA_result|=(sampleA[i])<<(7-i);	
				//here I am hoping to get the bit, 
				//then place it into a specific location of the array.
				//This entire function can definitely be 
				//simplified by using pointers, but I don't really know how.
			}											
			if(one_or_zero==1)
			{
				sampleA_result|=(sampleA[i])<<(7-i);
			}
		}
		A=0;
		B=1;
	}
	if(B=1)
	{
		for(i=0;i<8;i++)
		{
			if(one_or_zero==0)
			{
				sampleB_result|=(sampleB[i])<<(7-i);
			}
			if(one_or_zero==1)
			{
				sampleB_result|=(sampleB[i])<<(7-i);
			}
		}
		B=0;
		C=1;
	}
	if(C=1)
	{
		for(i=0;i<8;i++)
		{
			if(one_or_zero==0)
			{
				sampleC_result|=(sampleC[i])<<(7-i);
			}
			if(one_or_zero==1)
			{
				sampleC_result|=(sampleC[i])<<(7-i);
			}
		}
		C=0;
		D=1;
	}
	if(D=1)
	{
		for(i=0;i<8;i++)
		{
			if(one_or_zero==0)
			{
				sampleD_result|=(sampleD[i])<<(7-i);
			}
			if(one_or_zero==1)
			{
				sampleD_result|=(sampleD[i])<<(7-i);
			}
		}
		D=0;
		A=1;
	}
}
///////////////////////////////////////////////////////
void average(void)
{
	sample_result=(sampleA_result+sampleB_result+sampleC_result+sampleD_result)>>3;	
	//taking 32 bits that have been accumulated 
	//and finding an average 
	//of how many are 1's. The bit-shift should be equal to 32/4.
	if(sample_result<0x06)	//if I get less than seven 1's in my averaged result something happens
	{
		//something happens
	}
}

if all you need are the average values, why do you need to store the 1's and 0's in an array? why not just count the number of ones's present every 8 bits and use that to find your average?
what do you know about the incoming signal frequencies? how do they compare to your "chip" frequency? if i am not mistaken your "chip" only supports edge detection so frequency comparison is critical,if comparison is good i would suggest using interrupts to sample the frequency