UM11029
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© NXP Semiconductors N.V. 2017. All rights reserved.
User manual
Rev. 1.0 — 16 June 2017
483 of 515
NXP Semiconductors
UM11029
Chapter 29: LPC84x CRC engine
29.6.2 CRC seed register
29.6.3 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.
29.6.4 CRC data register
This register is a Write-only register containing the data block for which the CRC sum will
be calculated.
29.7 Functional description
The following sections describe the register settings for each supported CRC standard:
29.7.1 CRC-CCITT set-up
Polynomial = x
16
+ x
12
+ x
5
+ 1
Seed Value = 0xFFFF
Bit order reverse for data input: NO
1's complement for data input: NO
Bit order reverse for CRC sum: NO
1's complement for CRC sum: NO
CRC_MODE = 0x0000 0000
CRC_SEED = 0x0000 FFFF
Table 468. 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 469. 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
Table 470. CRC data register (WR_DATA, address 0x5000 0008) bit description
Bit
Symbol
Description
Reset
value
31:0
CRC_WR_DATA
Data written to this register will be taken to perform CRC
calculation with selected bit order and 1’s complement
pre-process. Any write size 8, 16 or 32-bit are allowed and
accept back-to-back transactions.
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