Cypress CY7C63310, CY7C638xx manual WriteBlock Parameters Name Address Description, Block Block n

CY7C63310, CY7C638xx

9.5.3 WriteBlock Function

The WriteBlock function is used to store data in the Flash. Data is moved 64 bytes at a time from SRAM to Flash using this function. The WriteBlock function first checks the protection bits and determines if the desired BLOCKID is writable. If write protection is turned on, the WriteBlock function exits setting the accumulator and KEY2 back to 00h. KEY1 has a value of 01h, indicating a write failure. The configuration of the WriteBlock function is straightforward. The BLOCKID of the Flash block, where the data is stored, must be determined and stored at SRAM address FAh.

The SRAM address of the first of the 64 bytes to be stored in Flash must be indicated using the POINTER variable in the parameter block (SRAM address FBh). Finally, the CLOCK and DELAY value must be set correctly. The CLOCK value deter- mines the length of the write pulse that is used to store the data in the Flash. The CLOCK and DELAY values are dependent on the CPU speed and must be set correctly.

Table 9-5. WriteBlock Parameters

Name	Address	Description
KEY1	0,F8h	3Ah
KEY2	0,F9h	Stack Pointer value, when SSC is
		executed.
BLOCKID	0,FAh	8KB Flash block number (00h–7Fh)
		4KB Flash block number (00h–3Fh)
		3KB Flash block number (00h–2Fh)
POINTER	0,FBh	First of 64 addresses in SRAM, where
		the data to be stored in Flash is
		located before calling WriteBlock.
CLOCK	0,FCh	Clock divider used to set the write
		pulse width.
DELAY	0,FEh	For a CPU speed of 12 MHz set to
		56h.

9.5.4 EraseBlock Function

The EraseBlock function is used to erase a block of 64 contiguous bytes in Flash. The EraseBlock function first checks the protection bits and determines if the desired BLOCKID is writable. If write protection is turned on, the EraseBlock function exits setting the accumulator and KEY2 back to 00h. KEY1 has a value of 01h, indicating a write failure. The EraseBlock function is only useful as the first step in programming. When a block is erased, the data in the block is not one hundred percent unreadable. If the objective is to obliterate data in a block, the best method is to perform an EraseBlock followed by a Write- Block of all zeros.

To set up the parameter block for the EraseBlock function, correct key values must be stored in KEY1 and KEY2. The block number to be erased must be stored in the BLOCKID variable and the CLOCK and DELAY values must be set based on the current CPU speed.

Table 9-6. EraseBlock Parameters

Name	Address	Description
KEY1	0,F8h	3Ah
KEY2	0,F9h	Stack Pointer value, when SSC is
		executed.
BLOCKID	0,FAh	Flash block number (00h–7Fh)
CLOCK	0,FCh	Clock divider used to set the erase
		pulse width.
DELAY	0,FEh	For a CPU speed of 12 MHz set to
		56h

9.5.5 ProtectBlock Function

The enCoRe II devices offer Flash protection on a block by block basis. Table 9-7lists the protection modes available. In this table, ER and EW indicate the ability to perform external reads and writes. For internal writes, IW is used. Internal reading is permitted by way of the ROMX instruction. The ability to read by way of the SROM ReadBlock function is indicated by SR. The protection level is stored in two bits according to Table 9-7. These bits are bit packed into the 64 bytes of the protection block. As a result, each protection block byte stores the protection level for four Flash blocks. The bits are packed into a byte, with the lowest numbered block’s protection level stored in the lowest numbered bits Table 9-7.

The first address of the protection block contains the protection level for blocks 0 through 3; the second address is for blocks 4 through 7. The 64th byte stores the protection level for blocks 252 through 255.

Table 9-7. Protection Modes

Mode	Settings				Description	Marketing
00b	SR ER EW IW				Unprotected	Unprotected
01b	SR	ER	EW IW		Read protect	Factory upgrade
10b	SR	ER	EW	IW	Disable external	Field upgrade
					write
11b	SR	ER	EW	IW	Disable internal	Full protection
					write

7	6	5	4	3	2	1	0
Block	n+3	Block	n+2	Block	n+1	Block n

The level of protection is only decreased by an EraseAll, which places zeros in all locations of the protection block. To set the level of protection, the ProtectBlock function is used. This function takes data from SRAM, starting at address 80h, and ORs it with the current values in the protection block. The result of the OR operation is then stored in the protection block. The EraseBlock function does not change the protection level for a block. Because the SRAM location for the protection data is fixed and there is only one protection block per Flash macro, the ProtectBlock function expects very few variables in the parameter block to be set before calling the function. The parameter block values that must be set, besides the keys, are the CLOCK and DELAY values.

Document 38-08035 Rev. *K Page 16 of 83

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