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UM10601
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© NXP B.V. 2012. All rights reserved.
Preliminary user manual
Rev. 1.0 — 7 November 2012
229 of 313
NXP Semiconductors
UM10601
Chapter 18: LPC800 Cyclic Redundancy Check (CRC) engine
18.7.1 CRC mode register
18.7.2 CRC seed register
18.7.3 CRC checksum register
This register is a Read-only register containing the most recent checksum. The read
request to this register is automatically delayed by a finite number of wait states until the
results are valid and the checksum computation is complete.
18.7.4 CRC data register
This register is a Write-only register containing the data block for which the CRC sum will
be calculated.
Table 202. CRC mode register (MODE, address 0x5000 0000) bit description
Bit
Symbol
Description
Reset value
1:0
CRC_POLY
CRC polynom:
1X= CRC-32 polynomial
01= CRC-16 polynomial
00= CRC-CCITT polynomial
00
2
BIT_RVS_WR
Data bit order:
1= Bit order reverse for CRC_WR_DATA (per byte)
0= No bit order reverse for CRC_WR_DATA (per byte)
0
3
CMPL_WR
Data complement:
1= 1’s complement for CRC_WR_DATA
0= No 1’s complement for CRC_WR_DATA
0
4
BIT_RVS_SUM
CRC sum bit order:
1= Bit order reverse for CRC_SUM
0= No bit order reverse for CRC_SUM
0
5
CMPL_SUM
CRC sum complement:
1= 1’s complement for CRC_SUM
0=No 1’s complement for CRC_SUM
0
31:6 Reserved
Always 0 when read
0x0000000
Table 203. CRC seed register (SEED, address 0x5000 0004) bit description
Bit
Symbol
Description
Reset value
31:0
CRC_SEED A write access to this register will load CRC seed value to
CRC_SUM register with selected bit order and 1’s
complement pre-processes.
Remark:
A write access to this register will overrule the
CRC calculation in progresses.
0x0000 FFFF
Table 204. CRC checksum register (SUM, address 0x5000 0008) bit description
Bit
Symbol
Description
Reset value
31:0
CRC_SUM
The most recent CRC sum can be read through this
register with selected bit order and 1’s complement
post-processes.
0x0000 FFFF