1. Article purpose[edit source]
The purpose of this article is to explain how to monitor HSE clock.
If HSE is used in your clock tree, this can be a good idea to monitoring HSE to detect and avoid over frequency. The LPTIM mechanism will detect an over frequency and trig a tamper event which runs some actions (STM32MP13_Tamper_configuration).
2. How to activate the monitoring[edit source]
By default, the HSE monitor is disabled in soc secure device tree:
hse_monitor: hse-monitor {
compatible = "st,freq-monitor";
counter = <&lptimer3 1 1 0 0>;
status = "disabled";
};
To activate HSE monitor add this node in your board secure device tree:
&hse_monitor {
status = "okay";
};