About STM32L100XX, stm32l151xx, stm32l152xx, Stm32l162xx's Reset

There are three kinds of Reset:system reset, Power Reset, RTC domain reset.

• System Reset

  System resets all registers, except for the RTC,RTC backup register and the control/status register RCC_CSR.

  The system resets are generated in the following scenarios:

  1. Nrst Pin Pull Low

  2. Watchdog count End (WWDG reset)

  3. Independent watchdog technology End (IWDG reset)

  4. Software reset (SW reset)

  5. Low power Management Reset

  6. Option byte load reset

  7. Exit Standby mode

These reset sources can be confirmed by viewing the corresponding reset identification bit of the RCC_CSR register.

Software Reset

Reset the Sysresetreq bit of the register by setting the CORTEXT-M3 application interrupt and reset control (application Interrupt and reset controls). Need to refer to the CORTEXT-M3 kernel data.

Low power Management reset

The following two scenarios produce low power management resets:

1. Enter Standby mode:

The user option byte resets the Nrst_stdby bit to enable this reset. In this case, the device will go into the reset state instead of entering standby mode at any time after executing the sequence entering standby mode.

2. Enter Stop mode:

The user option byte resets the nrst_stop bit to enable this reset. In this case, the device will enter the reset state instead of entering stop mode at any time after executing the sequence entering stop mode.

option byte load reset

The obl_launch position of the FLASH_PECR Register 1 generates the option byte to load the reset. This bit is used to load option bytes in software mode.

• Power Reset

When a power reset occurs:

1.power-on/power-down Reset (por/pdr reset)

2.BOR Reset

Power reset resets the values of all registers, including the RTC domain registers.

The resets generated by these reset sources allow the Nrst pin to remain low for the delay phase. The Reset service entry vector address is 0x0000_0004.

The system reset signal is also output on the Nrst pin. The pulser generates a minimum 20us reset time for each internal reset source. In the case of external reset, the reset pulse is generated when the Nrst pin is pulled low.

• RTC and Backup Register reset

In the following two cases, you can reset the RTC perimeter, RTC Clock Source Selection (RCC_CSR), and the backup register:

1. Reset caused by the rtcrst of the RCC_CSR register.

2. Power Reset (BOR/POR/PDR)

About STM32L100XX, stm32l151xx, stm32l152xx, Stm32l162xx's Reset