Fujitsu FR81S Benutzerhandbuch
CHAPTER 38: CRC
4. Registers
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER
: CRC
FUJITSU SEMICONDUCTOR CONFIDENTIAL
7
4.1. CRC Control Register : CRCCR (CRC Control
Register)
The bit configuration of the CRC control register is shown below.
This register controls the CRC calculation.
CRCCR : Address 1133
H
(Access: Byte, Half-word, Word)
bit7
bit6
bit5
bit4
bit3
bit2
bit1
bit0
Reserved FXOR
CRCLSF CRCLTE LSBFST LTLEND CRC32
INIT
Initial value
0
0
0
0
0
0
0
0
Attribute R0,W0
R/W
R/W
R/W
R/W
R/W
R/W
R0,W
[bit7] Reserved
This bit must always be written to '0'.
[bit6] FXOR (Final XOR) : Final XOR Control bit
The result is caluculated XOR of "XOR value" and itself. The XOR values are ALL H and bit strings are
inverted when FXOR = 1 is true. This process is made in the latter part of the CRC register, and the result is
reflected in the CRC result readout value immediately after this bit setting.
[bit5] CRCLSF (CRC result LSb First) : CRC result bit order setting bit
This bit sets bit orders for CRC results. Changes the bit order in a byte. When this bit is "0", MSB First is
applied, and when this bit is "1", LSB First is applied. This process is made in the latter part of the CRC
register, and the result is reflected in the CRC result readout value immediately after this bit setting.
[bit4] CRCLTE (CRC result LiTtle-Endian) : CRC result byte order setting bit
This bit sets byte orders for CRC results. Changes the byte order in a word. When this bit is "0", big endian is
applied, and when this bit is "1", little endian is applied. This process is made in the latter part of the CRC
register, and the result is reflected in the CRC result readout value immediately after this bit setting. When this
bit is set to 1 for CRC16, the result is output in 31 to 16 bits.
[bit3] LSBFST (LSB FirST) : Bit order setting bit
This bit sets bit orders. Specifies the first bit of a byte (8 bits). When this bit is "0", MSB First is applied, and
when this bit is "1", LSB First is applied. Four patterns of process order can be specified by combining the
LTLEND setting.
[bit2] LTLEND (LitTtLe-ENDian) : Byte order setting bit
This bit sets byte orders. This bit specifies byte orders in a writing width. When this bit is "0", big endian is
applied, and when this bit is "1", little endian is applied.
[bit1] CRC32 (CRC32) : CRC mode selecting bit
This bit selects a mode for CRC16 and CRC32. When CRC32=1 is true, the arithmetic operation mode of
CRC32 is applied.
[bit0] INIT (INITialize) : Initialization bit
Initialization bit. When "1" is written to this bit, software performs the initialization. This bit does not have a
value and "0" is always returned at readout. In initialization, hardware loads the value of the initial value
register to the CRC register. Initialization needs to be performed once at the beginning of the CRC
calculation.
MB91520 Series
MN705-00010-1v0-E
1276