Cypress CY7C601xx ユーザーズマニュアル

Document 38-16016 Rev. *E

Page 20 of 68

The Checksum function calculates a 16-bit checksum over a
user specifiable number of blocks, within a single Flash macro
(Bank) starting from block zero. The BLOCKID parameter is
used to pass in the number of blocks to calculate the checksum
over. A BLOCKID value of ‘1’ calculates the checksum of only
block 0, while a BLOCKID value of ‘0’ calculates the checksum
of all 256 user blocks. The 16-bit checksum is returned in KEY1
and KEY2. The parameter KEY1 holds the lower eight bits of the
checksum and the parameter KEY2 holds the upper eight bits of
the checksum.

The checksum algorithm executes the following sequence of
three instructions over the number of blocks times 64 to be
checksummed.
romx
add [KEY1], A
adc [KEY2], 0

Va

lid

Op

era

ting

R

eg

io

n

F8h

F9h

FAh

FBh

FCh

FDh

FEh

FFh

Table 0

Table 1

Table 2

Table 3

Table 4

Table 5

Table 6

Table 7

Silicon ID 

[15-8]

Silicon ID 

[7-0]

24 MHz 

IOSCTR 
at 3.30V

24 MHz 

IOSCTR 
at 3.00V

24 MHz 

IOSCTR 
at 2.85V

24 MHz 

IOSCTR 
at 2.70V

32 KHz 

LPOSCTR 

at 3.30V

32 KHz 

LPOSCTR 

at 3.00V

32 KHz 

LPOSCTR 

at 2.85V

32 KHz 

LPOSCTR 

at 2.70V

Family / 

Die ID

Revision 

ID

KEY1

0,F8h

3Ah

KEY2

0,F9h

Stack Pointer value when SSC is 
executed

BLOCKID

0,FAh

Number of Flash blocks to calculate 
checksum on