function. 
   Note: The address that is passed in this function can be an address that 
         resides in any Flash segment that has a chip select. For example, if 
         fs0 and fs5 are used in the design, passing an address in this function
         that resides in either fs0 or fs5 will invoke the bulk erase operation. */

/*
unsigned char flash_erase_bulk(
    volatile unsigned char xdata* flash_bulk_erase_address)
{
	unsigned char done;
 	unsigned char poll;
 	unsigned char error;
 	unsigned char err;

	done = FALSE;
   	err = FALSE;

	//  Note:  the following constants (FLASH_COMMON_XXXX)
	//     are declared type volatile in the header file 
	//	   so they are not optimized away by the compiler

	*(FLASH_COMMON_X555) = 0xAA;		// unlock main flash, write 0xAA to addess 0xX555
	*(FLASH_COMMON_XAAA) = 0x55;		// unlock main flash, write 0x55 to addess 0xXAAA
	*(FLASH_COMMON_X555) = 0x80;		// write 0x80 command to erase entire chip
	*(FLASH_COMMON_X555) = 0xAA;        	// continue unlock sequence
	*(FLASH_COMMON_XAAA) = 0x55;		// continue unlock sequence
	*(FLASH_COMMON_X555) = 0x10;		// write 0x10 command to complete erase command

	do		  			// now use dat polling method to verify successful erase
    {  
		poll = *(flash_bulk_erase_address); 	// read flash status from any address
		                                // within the defined flash address space

		error = poll & NVM_ERROR;	// save timeout error bit at DQ5

		poll = poll & NVM_DATA_POLL;	// look at D7   

		if (poll == NVM_DATA_POLL)	// compare DQ7 

			done = TRUE;		// bulk erase OK,
						// indicate successful exit criteria

		else if (error == NVM_ERROR)	// check for timeout error   
			err = TRUE;		// indicate timeout error occurred

    } while((done == FALSE) && (err == FALSE)); 


	if (err == TRUE)			// make sure timeout error and dat poll didn't 
						// occur simultaneously
    {
		poll = *(flash_bulk_erase_address); 	// Read flash status again

		poll = poll & NVM_DATA_POLL;	// get DQ7 of poll byte read from flash  

		if (poll == NVM_DATA_POLL)	// compare DQ7 

			done = TRUE;		// the flash erased OK at the same
						// time timout error occured, indicate successful 
						// exit criteria

		*(FLASH_COMMON_X555) = 0xF0;  // reset the flash array (short reset instruction) 
		        // now delay 3 msec per dat sheet
    }

   	return(done);		// a successful flash erase returns 1, timeout error returns 0

}*/
/*
unsigned char flash_boot_erase_bulk(
    volatile unsigned char xdata* flash_bulk_erase_address)
{
	unsigned char done;
 	unsigned char poll;
 	unsigned char error;
 	unsigned char err;

	done = FALSE;
   	err = FALSE;

	//  Note:  the following constants (FLASH_COMMON_XXXX)
	//     are declared type volatile in the header file 
	//	   so they are not optimized away by the compiler

	*(FLASH_BOOT_X555) = 0xAA;		// unlock main flash, write 0xAA to addess 0xX555
	*(FLASH_BOOT_XAAA) = 0x55;		// unlock main flash, write 0x55 to addess 0xXAAA
	*(FLASH_BOOT_X555) = 0x80;		// write 0x80 command to erase entire chip
	*(FLASH_BOOT_X555) = 0xAA;        	// continue unlock sequence
	*(FLASH_BOOT_XAAA) = 0x55;		// continue unlock sequence
	*(FLASH_BOOT_X555) = 0x10;		// write 0x10 command to complete erase command

	do		  			// now use dat polling method to verify successful erase
         {  
         	poll = *(flash_bulk_erase_address); 	// read flash status from any address
		                                // within the defined flash address space
		
		error = poll & NVM_ERROR;	// save timeout error bit at DQ5

		poll = poll & NVM_DATA_POLL;	// look at D7   

		if (poll == NVM_DATA_POLL)	// compare DQ7 

			done = TRUE;		// bulk erase OK,
						// indicate successful exit criteria

		else if (error == NVM_ERROR)	// check for timeout error   
			err = TRUE;		// indicate timeout error occurred

         } while((done == FALSE) && (err == FALSE)); 


	if (err == TRUE)			// make sure timeout error and dat poll didn't 
						// occur simultaneously
         {
		poll = *(flash_bulk_erase_address); 	// Read flash status again

		poll = poll & NVM_DATA_POLL;	// get DQ7 of poll byte read from flash  

		if (poll == NVM_DATA_POLL)	// compare DQ7 

			done = TRUE;		// the flash erased OK at the same
						// time timout error occured, indicate successful 
						// exit criteria

		*(FLASH_BOOT_X555) = 0xF0;  // reset the flash array (short reset instruction) 
		        // now delay 3 msec per dat sheet
         }

   	 return(done);		// a successful flash erase returns 1, timeout error returns 0

}
*/


/*Module: flash_reset
  Resets the main Flash memory to Read Array mode.
  After this reset, the Flash memory may be read like a ROM device. 
  You'll need to include the header files generated by PSDsoft
  Express. */
/*
void flash_reset()	// reset flash, read array mode

{

	//  Note:  the following constants (FLASH_COMMON_XXXX)
	//     are declared type volatile in the header file 
	//	   so they are not optimized away by the compiler

	*(FLASH_COMMON_X555) = 0xAA;		// unlock main flash, write 0xAA to addess 0xX555
	*(FLASH_COMMON_XAAA) = 0x55;		// unlock main flash, write 0x55 to addess 0xXAAA
	*(FLASH_COMMON_X555) = 0xF0;		// write 0xF0 command to reset 
						// Flash memory to Read Array Mode
                      // now delay 3 msec per dat sheet
}*/



/* Module: flash_read_id
   Reads the Flash Identifier byte from main Flash memory. You'll need 
   to include the header files generated by PSDsoft Express.
   Important: The address passed to this function should be independent 
   of memory paging or else the PSD page register value should be set to 
   the correct page prior to calling this function.

   Note: The flash memory in the boot area of a PSD813F2 or PSD813F4 does 
   not provide an ID. Only the main Flash memory in all PSD813FX provides 
   an ID. */


/*
unsigned char flash_read_id(flash_id_address)	// read flash identifier
volatile unsigned char *flash_id_address;  

{
	unsigned char id;

	//  Note:  the following constants (FLASH_COMMON_XXXX)
	//     are declared type volatile in the header file 
	//	   so they are not optimized away by the compiler

	*(FLASH_COMMON_X555) = 0xAA;		// unlock main flash, write 0xAA to addess 0xX555
	*(FLASH_COMMON_XAAA) = 0x55;		// unlock main flash, write 0x55 to addess 0xXAAA
	*(FLASH_COMMON_X555) = 0x90;		// write 0x90 command to get ID

	id = *(flash_id_address);		// read flash status, address bit A6 = 0
						//				  A1 = 0
						//				  A0 = 1
	*(FLASH_COMMON_X555) = 0xF0;  // reset the flash array (short reset instruction) 
		        // now delay 3 msec per dat sheet

	return (id);				// return byte ID value
}
*/



/* Module: flash_erase_sector
   Erases the specified sector in main Flash memory.
   Need to include mapflash.h. Important: The address passed to this function 
   should be independent of memory paging or else the PSD page register should 
   be set to the correct page prior to calling this function. */


unsigned char flash_erase_sector(
     volatile unsigned char xdata * sector_erase_address)

{
	char done;

 	unsigned char poll;
 	unsigned char error;
	unsigned char err;
 
	done = FALSE;
										
	*(FLASH_COMMON_X555) = 0xAA;			// unlock main flash, write 0xAA to addess 0xX555
	*(FLASH_COMMON_XAAA) = 0x55;			// unlock main flash, write 0x55 to addess 0xXAAA
	*(FLASH_COMMON_X555) = 0x80;			// write 0x80 command 
	*(FLASH_COMMON_X555) = 0xAA;			// continue unlock sequence
	*(FLASH_COMMON_XAAA) = 0x55;			// continue unlock sequence
	*(sector_erase_address) = 0x30;		// write 0x30 command to indicate sector erase command


	do			// now use data polling method to verify successful erase
		{  
		poll = *(sector_erase_address); 	// read flash status from any address
		                                	// within the  flash address sector space
   		  								
		error = poll & NVM_ERROR;	    	// save timeout error bit at DQ5
                
		poll = poll & NVM_DATA_POLL;		// look at D7   
		
		if (poll == NVM_DATA_POLL)			// compare DQ7 

			done = TRUE;					// erase OK,
											// indicate successful exit criteria

		else if (error == NVM_ERROR)		// check for timeout error   

			err = TRUE;						// indicate timeout error occurred

		} while((done == FALSE) && (error == FALSE)); 


	if (err == TRUE)				// make sure timeout error and data poll didn't 
									// occur simultaneously
		{
		poll = *(sector_erase_address); 	// Read flash status again

		poll = poll & NVM_DATA_POLL;		// get DQ7 of poll byte read from flash  

		if (poll == NVM_DATA_POLL)			// compare DQ7 

			done = TRUE;					// the flash erased OK at the same
											// time timout error occured, indicate successful 

			*(FLASH_COMMON_X555) = 0xF0;  		// reset the flash array (short reset instruction) 

		}									// exit criteria

   	return(done);		// a successful flash erase returns 1, timeout error returns 0
}