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R01UH0336EJ0102 Rev.1.02
Page 385 of 1538
Jul 17, 2014
V850E2/PG4-L
Section 11 Data CRC Function A (DCRA)
(3)
DCRAnCTL
―
CRC Control Register
This register controls the CRC generation process.
Access
This register can be read/written in 8-bit units.
Address
<DCRAn_base1> + 20
H
Initial value
00
H
This register is initialized by any reset sources.
Note
After changing the CRC generating function (DCRAnCTL.DCRAnPOL), the
DCRAnCOUT register must be initialized.
Caution
The CRC bit width (DCRAnCTL.DCRAnISZn) must be set according to the
data block bit width. Switching the CRC bit width is not allowed during
processing of a data block (a data block consists of N bytes, half words, or
words). After the final CRC result is read from the DCRAnCOUT register, the
bit width can be changed. In that case, the register should be set again
according to Figure 11-2, Data CRC Function A Flow Diagram.
7
6
5
4
3
2
1
0
0
0
0
0
0
DCRAnISZ[1:0]
DCRAn
POL
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Table 11-7
DCRAnCTL Register Contents
Bit Position
Bit Name
Function
2, 1
DCRAnISZ[1:0]
Specifies the CRC input bit width.
00: 32 bits (DCRAnCIN[31:0])
01: 16 bits (DCRAnCIN[15:0])
10: 8 bits (DCRAnCIN[7:0])
11: Setting prohibited
0
DCRAnPOL
Specifies the CRC generating function.
0: 32-bit Ethernet CRC polynomial generation
The byte order of the DCRAnCIN register is LSB (least significant byte)
first, means LSB at bit position 7...0 of the DCRAnCIN register.
1: 16-bit CCITT CRC polynomial generation
The byte order of the DCRAnCIN register is MSB (most significant byte)
first, means MSB at bit position 7...0 of the DCRAnCIN register.