
R8C/36T-A Group
27. CRC Calculator Function
Under development Preliminary document
Specifications in this document are tentative and subject to change.
R01UH0240EJ0010 Rev.0.10
Page 664 of 728
Aug 05, 2011
27.2.2
CRC Control Register (CRCMR)
The CRCMR register is used to control both the CRC snoop and writes to and reads from registers CRCD and
CRCIN.
When writing data from the CPU to the CRCIN register, set both the CRCSW and CRCSR bits to 0.
When the CRCMS bit is set to 0, writes to registers CRCD and CRCIN are performed with the bit order
reversed.
When CRC code is read from the CRCD register, the bit-order-reversed CRC code is read. The bit order must
be reversed by a program.
When the CRCMS bit is set to 1, writes to registers CRCD and CRCIN do not reverse the bit order. When CRC
code is read from the CRCD register, the read CRC code is not bit-order-reversed.
When the CRCPS bit is set to 0, calculation is performed in CRT-CCITT mode and the result is stored in the
CRCD register.
When the CRCPS bit is set to 1, calculation is performed in CRC-16 mode and the result is stored in the CRCD
register.
Setting the CRCSR bit to 1 enables snooping of read operations on the data bus.
When the CRCSR bit is 1, if the address set in the CRCSAR register is read, CRC calculation is performed
automatically on the read data on the data bus and the result is stored in the CRCD register.
When the CRCSR bit is set to 1, set the CRCSW bit to 0.
Setting the CRCSW bit to 1 enables snooping of write operations on the data bus.
When the CRCSW bit is 1, if the address set in the SRCSAR register is written, CRC calculation is performed
automatically on the written data on the data bus and the result is stored in the CRCD register.
When the CRCSW bit is set to 1, set the CRCSR bit to 0.
Address 00292h
Bit
b7b6
b5b4b3
b2b1b0
After Reset
0
000
0000
Bit
Symbol
Bit Name
Function
R/W
b0
CRCMS CRC mode select bit
0: LSB first
1: MSB first
R/W
b1
CRCPS
CRC polynomial select bit
0: X16 + X12 + X5 + 1 (CRC-CCITT)
1: X16 + X15 + X2 + 1 (CRC-16)
R/W
b5 to b2
—
Nothing is assigned. The write value must be 0. The read value is 0.
—
b6
CRCSR Snoop-on-read enable bit
0: Disabled
1: Enabled
R/W
b7
CRCSW Snoop-on-write enable bit
R/W