CYRF69103
Document #: 001-07611 Rev *C
Page 21 of 65
EraseBlock Function
The EraseBlock function is used to erase a block of 64
contiguous bytes in Flash. The first thing the EraseBlock function
does is to check the protection bits and determine if the desired
BLOCKID is writable. If write protection is turned on, the Erase-
Block function will exit, setting the accumulator and KEY2 back
to 00h. KEY1 will have a value of 01h, indicating a write failure.
The EraseBlock function is only useful as the first step in
programming. Erasing a block will not cause data in a block to
be one hundred percent unreadable. If the objective is to oblit-
erate data in a block, the best method is to perform an Erase-
Block followed by a WriteBlock 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.
ProtectBlock Function
The
CYRF69103
device
offers
Flash
protection
on
a
block-by-block basis. Table 29 lists the protection modes
available. In the table, ER and EW are used to indicate the ability
to perform external reads and writes. For internal writes, IW is
used. Internal reading is always 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 29. These bits are bit packed into the 64
bytes of the protection block. Therefore, 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.
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 will store the protection level for blocks
252 through 255.
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 prior to calling the function. The
parameter block values that must be set, besides the keys, are
the CLOCK and DELAY values.
EraseAll Function
The EraseAll function performs a series of steps that destroy the
user data in the Flash macros and resets the protection block in
each Flash macro to all zeros (the unprotected state). The
EraseAll function does not affect the three hidden blocks above
the protection block in each Flash macro. The first of these four
hidden blocks is used to store the protection table for its eight
Kbytes of user data.
The EraseAll function begins by erasing the user space of the
Flash macro with the highest address range. A bulk program of
all zeros is then performed on the same Flash macro, to destroy
Table 27. WriteBlock Parameters
Name
Address
Description
KEY1
0,F8h
3Ah
KEY2
0,F9h
Stack Pointer value, when SSC is
executing
BLOCK ID
0,FAh
8-KB Flash block number (00h–7Fh)
4-KB Flash block number (00h–3Fh)
3-KB Flash block number (00h–2Fh)
POINTER
0,FBh
First 64 addresses in SRAM where
the data to be stored in Flash is
located prior to 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
Table 28. 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
Table 29. 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
write
Field upgrade
11b
SR ER EW IW Disable internal
write
Full protection
76
54
32
10
Block n+3
Block n+2
Block n+1
Block n
Table 30. ProtectBlock Parameters
Name
Address
Description
KEY1
0,F8h
3Ah
KEY2
0,F9h
Stack Pointer value when SSC is
executed
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
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