C8051F997-GUR Silicon Labs, C8051F997-GUR Datasheet - Page 170

• Manufacturer Part Number: C8051F997-GUR
• Description: 8-bit Microcontrollers - MCU 8kB 14-CH CDC
• Manufacturer: Silicon Labs

Specifications of C8051F997-GUR

• Rohs: yes
• Core: 8051
• Processor Series: C8051
• Data Bus Width: 8 bit

C8051F99x-C8051F98x
16. Cyclic Redundancy Check Unit (CRC0)
C8051F99x-C8051F98x devices include a cyclic redundancy check unit (CRC0) that can perform a CRC
using a 16-bit polynomial. CRC0 accepts a stream of 8-bit data written to the CRC0IN register. CRC0 posts
the 16-bit result to an internal register. The internal result register may be accessed indirectly using the
CRC0PNT bits and CRC0DAT register, as shown in Figure 16.1. CRC0 also has a bit reverse register for
quick data manipulation.
16.1. CRC Algorithm
The C8051F99x-C8051F98x CRC unit generates a CRC result equivalent to the following algorithm:
1. XOR the input with the most-significant bits of the current CRC result. If this is the first iteration of the
2a. If the MSB of the CRC result is set, shift the CRC result and XOR the result with the selected
2b. If the MSB of the CRC result is not set, shift the CRC result.
Repeat Steps 2a/2b for the number of input bits (8). The algorithm is also described in the following exam-
ple.
170
CRC unit, the current CRC result will be the set initial value 
(0x00000000 or 0xFFFFFFFF).
polynomial.
CRC0FLIP
CRC0FLIP
CRC0PNT0
CRC0SEL
CRC0INIT
CRC0VAL
Write
Read
Figure 16.1. CRC0 Block Diagram
CRC0IN
CRC Engine
Rev. 1.1
8
8
RESULT
2 to 1 MUX
16
8
8
8
Automatic CRC
Controller
CRC0AUTO
CRC0DAT
CRC0CNT
Memory
Flash