di2688.txt
;************************************************************************************************
; LISTING 1 - VIRTUAL EEPROM C CODE
;
; "Microcontroller eliminates offboard EEPROM with "virtual-EEPROM" routines," EDN, May 10, 2001, pg 123
;
; http://www.ednmag.com/ednmag/reg/2001/051001/designideas.htm#11di1
;************************************************************************************************

// Virtual E2 demonstration files

#include "8cbr.h"; 	// COP8CBR Include Files
#include "flash_OP.h";	// Flash Operation Files

void veeprom_write(unsigned int data);  	// Prototype header for the virtual E2 write
void veeprom_read(void);			// Prototype header for the virtual E2 read	

unsigned int write_counter;   	 // The counter to hold how many write to allow
unsigned int write_pointer;    	// The pointer to where the current write is
unsigned int total_write;      	// Counter to tell how many write has already passed

unsigned int scratch_RAM[128]; 	// Create a 128 byte virtual E2



// Begining of Main

void main(){
        

// Set the total written to equal = 5
          	total_write=0x05;
          	write_counter=total_write;


          	// Store a 0x1E in the first byte of the virtual E2
          	veeprom_write(0x1E);

	// Zero the write counter
	total_write=0; 	

          	// Do an entire read of the Virtual E2
          	veeprom_read();

}


// Subroutine to write data to the Virtual E2
void veeprom_write(unsigned int data){


            unsigned int i;                			// A counter variable
            scratch_RAM[total_write]=data; 		// Write the data to the scratch RAM

            if (total_write==0){         			// Flush immediately
                  page_erase (0x3000);     			// Erase the 0x3000 page

             for (i=0; i<write_counter; i++){    		// If 0  bytes, then
                  cwritebf (0x3000 + i, scratch_RAM[i]); 	 // Flush all the bytes written to the RAM!

                  }
	else {
total_write=total_write-1;		 // Decrement the total counter
	        }

}


}

// Subroutine to read the entire 128 byte virtual E2
void veeprom_read(){

        unsigned int i;                 	// A counter variable
        for (i=0; i<128; i++){     	// Write the entire contents of the 128
            readbf(0x3000+i);      	// byte page into the scratch RAM @ 0x3000
            scratch_RAM[i]=ISPRD;  	// section
            }

        total_write=128;		// Total amount of write is = 128

}