/*!
    \file    readme.txt
    \brief   description of system clock switch example with TZEN=1

    \version 2026-04-15, V2.0.0, firmware for gd32w51x_f5hc
*/

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  This example is based on the GD32W515P-EVAL-V1.0/GD32F5HCR-EVAL-V1.0, the project consists of
two sub-projects, secure project and non-secure project. It shows how to switch from
secure application to non-secure application, and call secure functions in non-secure
application. The switch_system_clock_to_120m_hxtal function and switch_system_clock_to_180m_irc16m
function is defined in non-secure callable area in secure application, and is called
by non-secure application.
  The system always starts from the secure application, and the secure application is
responsible for starting the non-secure application.Therefore, in the compilation process,
first compile the secure project, and then compile the non-secure project.
  Before downloading the program, the option byte needs to be configured as follows:
    1.enable trust-zone
        TZEN = 1
    2.configure secure mark pages
        FMC_SECMCFG0 = 0x003F0000
        start-page :0x00  end-page:0x3F  means that the first 64 pages of flash are configured
        as secure
  In secure application,the program execution follows the following steps:
    1.configure SAU/IDAU, FPU and secure/no-secure interrupts allocations in partition_gd32w51x_f5hc.h file
    the key configuration is as follows:
        Enable SAU
        SAU Region 0  start address: 0x0C03E000   end address: 0xC003FFFF  Attributes: S/NSC
        SAU Region 1  start address: 0x08040000   end address: 0x08200000  Attributes: NS
        SAU Region 2  start address: 0x20010000   end address: 0x2001FFFF  Attributes: NS
        SAU Region 3  start address: 0x40000000   end address: 0x4FFFFFFF  Attributes: NS
        EXTI2 IRQn configure as Non-Secure State
    2.configure TZBMPC
        TZBMPC1 vector register y(y=0 to 7):0x00000000 means that SRAM1(64KB) are configured as non-secure
    3.Setup and jump to non-secure application
  In non-secure application, when the KEY_TAMPER_WAKEUP is pressed, the system performs a clock switch by
non-secure function defined in secure project, and then update the systick config, the LED1 blinking frequency 
will be changed. When system clock switches to 180MHz(GD32W515)/200MHz(GD32F5HC), LED2 turns on and LED3 turns off;
When system clock switches to 120MHz, LED3 turns on and LED2 turns off.
