SW4STM32C datasheet(41/99 Pages) STMICROELECTRONICS

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Breaking and stepping into code

This chapter provides users with highlights about a few points affecting system behavior at

code break.

5.1

Debug support for timers, RTC, watchdog, BxCAN and I2C

During a breakpoint, it is necessary to choose how the counter of timers, RTC and

watchdog should behave:

•

They can continue to count inside a breakpoint. This is usually required when a PWM is

controlling a motor, for example.

•

They can stop counting inside a breakpoint. This is required for watchdog purposes.

For the BxCAN, the user can choose to block the update of the receive register during a

breakpoint.

For the I2C, the user can choose to block the SMBUS timeout during a breakpoint.

Those options are accessible in DBGMCU freeze registers (DBGMCU_APB1FZR1,

DBGMCU_APB1FZR2) which can be written by the debugger under system reset.

If the debugger host does not support these features, it is still possible to write these

registers by software.

Refer to Appendix A: Managing DBGMCU registers on page 78 to find suitable ways to

handle debug options depending on IDEs and needs.

5.2

Debug performance

To save flashing time and improve debugger reactivity when stepping, make sure that the

higher SWD frequency possible is used with the probe.

When using ST-LINK utility, IAR™ EWARM, or Keil® MDK-ARM µVISION speed is set at

1.8 MHz by default. On system with a core clock greater than 1 MHz, it is safe to use the

highest 4 MHz SWD speed.

SW4STM32C Datasheet(PDF) 41 Page - STMicroelectronics