STPM066S datasheet(30/67 Pages) STMICROELECTRONICS

부품명	STPM066S

상세설명	Power management for automotive vision and radar systems

PDF	67 Pages

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제조업체	STMICROELECTRONICS [STMicroelectronics]

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5.1

SPI frame CRC generator

The SPI protocol is defined by frames of 32 bits with 5 bits of CRC (Cyclic Redundancy Check) in both input and

output directions. The polynomial calculation implemented is:

g(x)= x^5 + x^2 + 1

the structure of CRC generator is shown in Figure 19. Structure of CRC generator.

Here are the rules:

For DI, CNT=DI[21] is ignored when calculating CRC, it means only {DI[31:22],DI[20:5]} is used to calculate

CRC. For example, if DI[31:5]=27‘b1000_0010_1011_1111_1111_1111_111, the CRC[4:0]= 5‘b0_0011

For DO, DO[21] is ignored when calculating CRC, it means only {DO[31:22],DO[20:5]} is used to calculate

CRC.

The initial value of CRC generator is 5'b1_1111.

MSB (DI[31]) is shift in CRC generator at first.

Figure 19. Structure of CRC generator

XOR

MOSI

BIT4

XOR

BIT1

BIT0

BIT3

BIT2

GAPG2402160858PS

STPM066S

SPI frame CRC generator

DS12976 - Rev 2

page 30/67

STPM066S 데이터시트(PDF) 30 Page - STMicroelectronics