2019-03-12 12:17 AM
Hello.
I am using STM32F407ZG. I would like to use CSS functionality for clock monitoring and switching. I need a help for using CSS.
Thanks in advance.
2019-10-17 01:10 AM
Hello !
2019-10-17 01:15 AM
From RM0385 for STM32F74xxx u can read:
it is directly used as PLL input clock, and that PLL clock is the system clock) and a failure is
detected, then the system clock switches to the HSI oscillator and the HSE oscillator is
disabled.
2.
When the CSS is enabled, if the HSE clock happens to fail, the CSS generates an interrupt,
which causes the automatic generation of an NMI. The NMI is executed indefinitely unless
the CSS interrupt pending bit is cleared. As a consequence, the application has to clear the
CSS interrupt in the NMI ISR by setting the CSSC bit in the Clock interrupt register
(RCC_CIR).
2020-05-07 09:28 AM
@Clive Vallance
I have the following situation.
HSI oscillator and HSE/Bypass clock (not the HSE oscillator) are both activated. HSE clock is the source of PLL. PLL clock is the source of SYSCLK.
Clock Security is enabled. NMI will clear the flag as well.
The reference manual about Clock Security System refers to HSE oscillator but not HSE clock.
If HSE clock fails, will the HSI clock take it over?