M30622MA-XXXFP RENESAS [Renesas Technology Corp], M30622MA-XXXFP Datasheet - Page 180

• Manufacturer Part Number: M30622MA-XXXFP
• Description: 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY
• Manufacturer: RENESAS [Renesas Technology Corp]

CRC
CRC Calculation Circuit
Figure 1.22.1. Block diagram of CRC circuit
Figure 1.22.2. CRC-related registers
The Cyclic Redundancy Check (CRC) calculation circuit detects an error in data blocks. The microcom-
puter uses a generator polynomial of CRC_CCITT (X
The CRC code is a 16-bit code generated for a block of a given data length in multiples of 8 bits. The CRC
code is set in a CRC data register each time one byte of data is transferred to a CRC input register after
writing an initial value into the CRC data register. Generation of CRC code for one byte of data is com-
pleted in two machine cycles.
Figure 1.22.1 shows the block diagram of the CRC circuit. Figure 1.22.2 shows the CRC-related registers.
Figure 1.22.3 shows the calculation example using the CRC calculation circuit
(b15)
CRC data register
b7
b7
CRC input register
(b8)
b0 b7
b0
CRC input register (8)
CRC calculation result output register
Data input register
Data bus high-order bits
Data bus low-order bits
CRC code generating circuit
Eight low-order bits
CRC data register (16)
x
16
b0
+ x
12
+ x
(Address 03BE
Symbol
CRCD
Symbo
CRCIN
Function
Function
5
+ 1
16
+ X
12
03BD
16
)
+ X
Eight high-order bits
Address
16
Address
03BE
5
, 03BC
+ 1) to generate CRC code.
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
16
(Addresses 03BD
16
0000
Values that
Values that
can be set
Indeterminate
00
can be set
Indeterminate
When reset
When reset
16
16
to FFFF
to FF
16
16
16
, 03BC
Mitsubishi microcomputers
M16C / 62 Group
R
R
W
W
16
)
165