STM32L151XD datasheet(31/140 Pages) STMICROELECTRONICS

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STM32L151xD STM32L152xD

Functional overview

Doc ID 022027 Rev 6

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48 MHz clock is generated from the internal main PLL (the clock source must use a HSE

crystal oscillator).

3.19

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.

3.20

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 JTMS and JTCK pins are shared with SWDAT and SWCLK, respectively, and a

specific sequence on the JTMS 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® Embedded Trace Macrocell provides a greater visibility of the instruction and

data flow inside the CPU core by streaming compressed data at a very high rate from the

STM32L15xxD 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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