Crc (Cyclic Redundancy Check) Calculation Unit; Development Support - STMicroelectronics STM32L151CB Manual

Functional overview
3.16

CRC (cyclic redundancy check) calculation unit

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.
3.17

Development support

Serial wire JTAG debug port (SWJ-DP)
The ARM SWJ-DP interface is embedded, and is a combined JTAG and serial wire debug
port that enables either a serial wire debug or a JTAG probe to be connected to the target.
The JTAG TMS and TCK pins are shared with SWDIO and SWCLK, respectively, and a
specific sequence on the TMS pin is used to switch between JTAG-DP and SW-DP.
The JTAG port can be permanently disabled with a JTAG fuse.
Embedded Trace Macrocell™
The ARM
data flow inside the CPU core by streaming compressed data at a very high rate from the
STM32L15xxx through a small number of ETM pins to an external hardware trace port
analyzer (TPA) device. The TPA is connected to a host computer using USB, Ethernet, or
any other high-speed channel. Real-time instruction and data flow activity can be recorded
and then formatted for display on the host computer running debugger software. TPA
hardware is commercially available from common development tool vendors. It operates
with third party debugger software tools.
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Embedded Trace Macrocell provides a greater visibility of the instruction and
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Doc ID 17659 Rev 6
STM32L151xx, STM32L152xx