CMS32L051 User Manual |Chapter 24 Security Features
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24.3.2.2 CRC data register (CRCD)
This is the register that holds the results of a general-purpose CRC operation. The range that can be set is
0000H~FFFFH.
After writing the CRCIN register, a CPU/peripheral hardware clock (f
C
LK) is passed to save the CRC
operation results to the CRCD Register. The CRCD registers are set via 16-bit memory operation instructions.
After the reset signal is generated, the value of this register changes to 0000H.
Figure 24-5 Format of CRC data register (CRCD)
Address: 400432FAH after reset: 0000HR/W
Symbol
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
CRCD
Note 1. To read the write value of a CRCD register, the CRCD register must be read before the CRCIN register is written.
2. If the write operation of the CRCD register competes with the saving of the operation result, the write operation is ignored.
< Operation process >
Figure 24-6 Flowchart of CRC operation function (general CRC)
Start
save start and end address to general registerappointed start and end address
perform initalization of CRCD register
read 8 bit data from corresponding address
calculate CRC of 8 bit data
write "0000H" into CRCD register
read data
save data into CRCIN register
Address +1
last address?
wait for 1 clock cycle
read CRCD register
End
take CRC result
compare with prepared expected
value, confirm the value is identical
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