/*!
\file readme.txt
\brief description of USART printf example with TZEN=1
\version 2021-10-30, V1.0.0, firmware for GD32W51x
*/
/*
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*/
This example is based on the GD32W515P-EVAL-V1.0 board, the project consists of
two sub-projects, secure project and nonsecure project. It shows how to switch between
secure application and non-secure application.
The system always starts from the secure application, and the secure application is
responsible for starting the nonsecure application.
In secure application,the program execution follows the following steps:
1.configre SAU/IDAU, FPU and secure/nosecure interrupts allocations in
partition_gd32w51x.h file the key configuration is as follows:
Enable SAU
SAU Region 0 start address: 0x0C03E000 end address: 0x0C03FFFF 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
2.enable trustzone
TZEN = 1
3.configure secure mark pages
startpage :0x00 endpage:0x3F means that the first 64 pages of flash are configured
as secure
4.configure TZBMPC
TZBMPC1 vector register y(y=0 to 7):0x00000000 means that SRAM1(64KB) are configured
as nonsecure
5.configure PB10, PB11 and USART to nonsecure.
6.configure and jump to non-secure application
In nonsecure application, by calling NSC area functions, it shows how to retarget the C
library printf function to the USART.
