M30245FCGP#U1 Renesas Electronics America, M30245FCGP#U1 Datasheet - Page 179

• Manufacturer Part Number: M30245FCGP#U1
• Description: IC M16C/24 MCU FLSH 128K 100LQFP
• Manufacturer: Renesas Electronics America
• Series: M16C™ M16C/20r

Specifications of M30245FCGP#U1

• Core Processor: M16C/60
• Core Size: 16-Bit
• Speed: 16MHz
• Connectivity: I²C, SPI, SSI, UART/USART, USB
• Peripherals: DMA, PWM, WDT
• Number Of I /o: 82
• Program Memory Size: 128KB (128K x 8)
• Program Memory Type: FLASH
• Ram Size: 10K x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -20°C ~ 85°C
• Package / Case: 100-LQFP
• Package: 100LQFP
• Family Name: R8C
• Maximum Speed: 16 MHz
• Operating Supply Voltage: 3.3 V
• Data Bus Width: 16 Bit
• Number Of Programmable I/os: 82
• Interface Type: USB/UART/I2C/SPI
• On-chip Adc: 8-chx10-bit
• Number Of Timers: 5
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -

M30245 Group
Figure 1.129. CRC circuit block diagram
Rev.2.00
REJ03B0005-0200
CRC calculation circuit
CRC Snoop
The Cyclic Redundancy Check (CRC) calculation circuit detects any errors in data blocks. The microcomputer 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. It is set in a CRC
data register every 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 completed in two machine cycles.
Figure 1.129 shows the block diagram of the CRC circuit. Figure 1.130 shows the CRC-related registers. Figure
1.131 shows an example of the CRC using CRC-CCITT.
The CRC circuit includes the ability to snoop reads and writes to certain SFR addresses. This can be used to
accumulate the CRC value on a stream of data without using extra bandwidth to explicitly write data into the CRCIN
register. For example, it may be useful to snoop the writes to a UART TX buffer, or the reads from a UART RX buffer.
This can only be used on USB, UART and SSI registers.
To snoop an SFR address, the target address is written to the CRC Snoop Address Register (CRCSAR). The two
most significant bits of this register enable snooping on reads or writes to the target address. If the target SFR is
written to by the CPU or DMA, and the CRC snoop write bit is set (CRCSW=1), the CRC will latch the data into the
CRCIN register. The new CRC code will be set in the CRCD register.
Similarly, if the target SFR is read by the CPU or DMA, and the CRC snoop read bit is set (CRCSR=1), the CRC will
latch the data from the target into the CRCIN register and calculate the CRC.
The CRC circuit can only calculate CRC codes on data one byte at a time. Therefore, if a target SFR is accessed in a
word (16 bit) bus cycle, only the byte of data going to or from the target is snooped into CRCIN. The other byte of the
word access is ignored.
Note: CRC Snoop can only be used to snoop USB, UART and SSI related SFR registers.
Oct 16, 2006
CRC input register (8)
x
16
page 177 of 264
+ x
Data bus high-order bits
Data bus low-order bits
CRC code generating circuit
Address Bus
12
Eight low-order bits
CRC data register (16)
+ x
5
+ 1
(Address 03BE
OR
x
16
+ x
16
16
15
)
+ x
+ x
12
2
+ 1
+ x
Eight high-order bits
5
+ 1) or CRC-16 (x
(Addresses 03BD
Enable
16
, 03BC
16
+ x
16
15
)
+ x
2
Snoop Address
+ 1) to generate CRC code.
Equal?
CRC Calculation Circuit
Snoop
enable
Snoop
Block