ST STM32F207 series User Manual

RM0033 Rev 9 61/1381
RM0033 CRC calculation unit
63
3 CRC calculation unit
This section applies to the whole STM32F20x and STM32F21x and family, unless otherwise
specified.
3.1 CRC introduction
The CRC (cyclic redundancy check) calculation unit is used to get a CRC code from a 32-bit
data word and a fixed generator polynomial.
Among other applications, CRC-based techniques are used to verify data transmission or
storage integrity. In the scope of the EN/IEC 60335-1 standard, they offer a means of
verifying the Flash memory integrity. The CRC calculation unit helps compute a signature of
the software during runtime, to be compared with a reference signature generated at link-
time and stored at a given memory location.
3.2 CRC main features
• Uses CRC-32 (Ethernet) polynomial: 0x4C11DB7
–X
32
+ X
26
+ X
23
+ X
22
+ X
16
+ X
12
+ X
11
+ X
10
+X
8
+ X
7
+ X
5
+ X
4
+ X
2
+ X + 1
• Single input/output 32-bit data register
• CRC computation done in 4 AHB clock cycles (HCLK)
• General-purpose 8-bit register (can be used for temporary storage)
The block diagram is shown in Figure 2.
Figure 2. CRC calculation unit block diagram
AHB bus
32-bit (read access)
Data register (output)
CRC computation (polynomial: 0x4C11DB7)
32-bit (write access)
Data register (input)
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ST STM32F207 series Specifications

General

Brand	ST
Model	STM32F207 series
Category	Microcontrollers
Language	English