Development Support; Serial Wire Jtag Debug Port (Swj-Dp); Embedded Trace Macrocell - STMicroelectronics STM32L151QCH6 Manual

STM32L151xC/C-A STM32L152xC/C-A
3.19

Development support

3.19.1

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.
3.19.2

Embedded Trace Macrocell™

The ARM
data flow inside the CPU core by streaming compressed data at a very high rate from the
STM32L151xC/C-A and STM32L152xC/C-A device 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.
® Embedded Trace Macrocell provides a greater visibility of the instruction and
DocID026119 Rev 5
Functional overview
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